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    2024,Volume 53, Issue 4

      >Special Issue:titanium alloy
    • Ma Xilong, Kazuhiro Matsugi, Shang Zhifeng, Su Hongji, Jia Bowen, Nie Guoquan

      2024,53(4):947-953 DOI: 10.12442/j.issn.1002-185X.20230381

      Abstract:Newly designed α-type titanium (α-Ti) alloys were proposed based on both electron parameters (bonding time Bot and d-orbital energy level Mdt). The newly designed α-Ti alloy Ti-5Al-4Zr-3.6Sn, modified alloy Ti-5Al-3Sn-1.9Zr, and reference alloy Ti-5Al-2.5Sn have the same Bot value of 3.847 and different Mdt values of 2.430, 2.426, and 2.422, respectively. The ultimate tensile strength (σUTS), fracture strain (?f), and hot salt corrosion resistance of the three α-Ti alloys were measured. The three α-Ti alloys were produced by the cold crucible levitation melting (CCLM) technique. Results show that homogeneous microstructures can be observed in three α-Ti alloys. The α mono-phase in three α-Ti alloys has the grain size of approximately 600 μm. σUTS and ?f of Ti-5Al-4Zr-3.6Sn alloy are 801 MPa and 16%, respectively; σUTS and ?f of Ti-5Al-3Sn-1.9Zr alloy are 708 MPa and 15%, respectively; σUTS and ?f of Ti-5Al-2.5Sn alloy are 603 MPa and 15%, respectively. After hot salt corrosion tests were conducted for 28.8 ks, the mass loss ratio of Ti-5Al-4Zr-3.6Sn, Ti-5Al-3Sn-1.9Zr, and Ti-5Al-2.5Sn alloys is 2.61%, 2.83%, and 3.10%, respectively. The results of σUTS, ?f, and hot salt corrosion resistance indicate that the newly designed alloy Ti-5Al-4Zr-3.6Sn has great potential for practical applications.

    • Lan Xinyue, Wang Ping, Gong Zeyu, Luo Xu, Zheng Youping, Deng Bowen

      2024,53(4):954-962 DOI: 10.12442/j.issn.1002-185X.20230376

      Abstract:Phytic acid, one kind of organic acid, was added into the electrolyte to enhance the corrosion performance and thermal stability of micro-arc oxidation (MAO) coating on TC4 titanium alloy. The effect of phytic acid on the coating formation, morphology, and performance was analyzed by scanning electron microscope, X-ray diffractometer, X-ray photoelectron spectroscope, and thermal shock experiments. Results show that the addition of phytic acid leads to the refinement of discharge microholes and improves the formation efficiency and phase structure of MAO coating. Through potentiodynamic polarization tests, it is found that adding phytic acid can significantly enhance the corrosion resistance of MAO coating. The corrosion current density decreases from 8.406×10-5 A·cm-2 to 2.580×10-6 A·cm-2 when the phytic acid concentration in electrolyte changes to 12 mL/L (optimal phytic acid concentration). Cyclic high temperature oxidation test results indicate that the thermal shock resistance and high temperature oxidation resistance of TC4 alloy are enhanced.

    • Liu Guozheng, Zhao Yongqing, Jia Weiju, Zhang Yan, Song Shuo, Mao Chengliang, Zhou Wei

      2024,53(4):970-977 DOI: 10.12442/j.issn.1002-185X.20230498

      Abstract:In order to satisfy the requirements of aerospace field for rapid preparation of high strength and toughness complex titanium alloy parts, new Ti-5321 (Ti-5Al-3Mo-3V-2Zr-2Cr-1Nb-1Fe) alloy with high strength and high toughness was prepared by laser cladding forming, which possesses the superiority of rapid prototyping, high efficiency, and good formability. Through single annealing and multiple heat treatment (β-annealing with slow cooling and aging, BASCA) on Ti-5321 alloy, the microstructure evolution was revealed, and the influence of different microstructures on the fracture toughness was explored. Results show that after single annealing, the alloy morphology presents the basket-weave structure consisting of elongated lamellar α phases. Its ultimate tensile strength is 1102 MPa, and fracture toughness is 68.1 MPa·m1/2. After BASCA heat treatment, the elongated lamellar α phase changes to coarse lamellar α phase and ultrafine needle-like α phase. Thus, the ultimate tensile strength increases to 1309 MPa, whereas the fracture toughness reduces to 45.5 MPa·m1/2. BASCA heat treatment can enhance the strength but degrade the toughness of alloys. This is because the elongated lamellar α phase in basket-weave structure can greatly increase the crack growth resistance and aggravate the tortuous degree of crack growth path, thus improving the alloy toughness. Coarse lamellar α phase after BASCA heat treatment has a certain degree of directionality, and the cracks only deflect when passing through the coarse lamellar α phase of different β grains. Crack propagation mainly occurs in the ultrafine needle-like α phase. However, due to the extremely small size of ultrafine needle-like α phase, it cannot hinder the development of crack path or deflect the cracks. Thus, the toughness of coarse lamellar structure becomes more inferior after BASCA heat treatment.

    • Ma Xianglong, Cao Rui, Dong Hao, Wang Tiejun, Yan Yingjie

      2024,53(4):1002-1010 DOI: 10.12442/j.issn.1002-185X.E20230024

      Abstract:Hot isostatic pressure diffusion bonding experiments were conducted on the dissimilar alloys of TC4 titanium alloy and Al6061 aluminum alloy. The interface characteristics, formation mechanism, and mechanical properties of the TC4/Al6061 joint were investigated, and the relevant experiment phenomena were explained by thermodynamic analysis. Results show that obvious mutual diffusion of elements occurs on both sides of base material after hot isostatic pressure diffusion bonding and subsequent annealing treatment. The chemical potential driving force leads to the enrichment of Si and Mg elements in the diffusion transition zone and Al side interface, respectively. The intermetallic compounds, including TiAl3, TiAl, and Ti3Al, are formed through metallurgical reactions at the joint interface. The calculation results through effective heat formation model indicate the preferential formation of TiAl3 phase. The hardness test indicates that the Ti-Al intermetallic compounds formed at the interface exhibit higher hardness. The tensile test reveals that the maximum tensile strength of joint reaches 144 MPa.

    • Huang Qi, Gao Xu, Liu Dong, Hei Bei

      2024,53(4):1058-1064 DOI: 10.12442/j.issn.1002-185X.20230150

      Abstract:In this paper, the microstructure and mechanical properties of integral bladed titanium alloy Ti60 repaired by laser were studied. The results showed that the heat affected zone structure presents the transition characteristics from the Dual structure of the matrix area to the mesh basket structure of the repair area, and its average width is about 900 μm. The repair zone is mainly composed of columnar crystals growing epitaxially through multiple sedimentary layers, and the columnar crystals are uniformly distributed α phase mesh basket structures. Ti3(Sn, Al) facet facies of similar size were dispersed in the structure of the three regions, but their morphology and regional content varied significantly due to the solidification speed of the preparation process. The three areas are equally hard. The fracture characteristics of tensile specimens show that the fracture mechanism of laser additive repaired Ti60 titanium alloy is mixed fracture. The average tensile strength and yield strength are 992.4 MPa and 916.6 MPa respectively, which are superior to the strength standard of Ti60 titanium alloy forgings, the average elongation and section shrinkage after fracture are 8.5% and 14.6% , which are similar to the standard of Ti60 titanium alloy forgings and meets the requirements of practical engineering application

    • LIU Chengxiang, HUANG Dongya, ZHOU Rongfeng, LIU Kun, LI Yongkun, YIN Xinhua, WEN Ke, ZHANG Yazhen

      2024,53(4):1120-1129 DOI: 10.12442/j.issn.1002-185X.20230061

      Abstract:Gleeble-1500 thermodynamic simulation machine was used to perform thermal compression deformation of pure titanium before and after the phase change point, and the influence of thermal compression on the phase transition was studied. It is found that when the stress is applied near the phase change point, the phase transition first occurs between the slats, and the newly formed β grains are mostly spherical or short rod-shaped. As the amount of compression increases, adjacent β nuclei gradually connect and become strip-like tissues. There is a critical value for phase transition, when the compression temperature is 860 °C, 890 °C and 920 °C, respectively, when the compression amount reaches 40%, 30% and 20%, the phase transition tends to saturate, replaced by a large number of dynamic recrystallization. The higher the temperature, the more obvious the phenomenon of deformation promoting phase change, when the compression temperature is after the phase change point, a small amount of compression can make a large number of phase transitions occur.

    • >Materials Science
    • Li Junwei, Jia Weimin, Liu Chong, Li Peiyao, Li Zhengcao

      2024,53(4):933-946 DOI: 10.12442/j.issn.1002-185X.20230402

      Abstract:The adsorption and dissociation of CO and CO2 molecules on UO2 (111) slab were investigated by the first-principles calculations based on density functional theory with the addition of Hubbard term for calculation correction. Different static and dynamic adsorption mechanisms under different configurations were analyzed, and the adsorption sites included top, hollow, and bridge sites. In the static calculations, the variation of adsorption parameters, such as adsorption configuration, adsorption energy, and charge transfer, during adsorption process was investigated. ab-initio molecular dynamics (AIMD) was employed to study the dissociation process of CO2 molecules and the changes in charge density difference. Results show that the adsorption of CO molecules can be categorized into two types: (1) stable adsorption, including chemical and physical adsorptions; (2) unstable adsorption. The adsorption types of CO2 on UO2 (111) slab only include the chemical adsorption of stable adsorption and unstable adsorption. No physical adsorption exists. The optimal configuration for the adsorption of both CO and CO2 molecules is short-bridge vertical (B-short-Ver) adsorption. Additionally, at 0 K, the CO2 molecules at the configurations related to B-short-Ver adsorption and long-bridge vertical adsorption on UO2 (111) slab spontaneously dissociate after adsorption. AIMD simulation results show that both configurations dissociate at 300 K.

    • Zhang Kefeng, Li Yan, Nie Kailong, Dang Shiyuan, Yao Bingxue, Hua Xue, Tian Guangyan

      2024,53(4):963-969 DOI: 10.12442/j.issn.1002-185X.E20230021

      Abstract:To enhance the dispersibility and photostability of AgCl nanoparticles (NPs), AgCl NPs were firmly anchored on the surface of attapulgite (ATP) to prepare the ATP-AgCl composites. The microstructure, crystal structure, and antibacterial activity of the ATP-AgCl composites were investigated. Results demonstrate that the introducion of ATP not only avoids the agglomeration of AgCl NPs, but also decreases their particle size from 5–10 μm to 3–20 nm. Due to the small size effect of NPs, the antibacterial activity of as-prepared ATP-AgCl composites is comparable to that of pure AgCl. The antibacterial ratios against Escherichia coli and Staphylococcus aureus are 99.98% and 99.88%, respectively. Additionally, the introduction of ATP also improves the photostability of AgCl NPs: the composites remains offwhite after exposure to sunshine for 24 h.

    • Miao Liguo, Xing Fei, Chai Yuanxin, Yan Chengxin, Liu Weijun

      2024,53(4):978-987 DOI: 10.12442/j.issn.1002-185X.20230356

      Abstract:According to the spatial distribution pattern of melt pool size features, a prediction method of melt pool width based on edge iterative model was proposed. In order to obtain accurate melt pool width, mathematical morphological method was used to denoise the melt pool image and coarse segmentation was conducted on the melt pool image by manual thresholding method. The Canny algorithm was then employed to extract the melt pool edge. Finally, the edge iterative model was used for edge iteration and the melt pool width after fine segmentation was obtained. Comparison experiment results show that this algorithm has good accuracy and robustness, and it is simple and efficient.

    • Liu Wansuo, Wang Zhibao, Wang Qing, Lin Zeng

      2024,53(4):988-993 DOI: 10.12442/j.issn.1002-185X.E20230023

      Abstract:The combined method of Navier-Stokes equation and direction simulation Monte-Carlo method was used to simulate the flow in the reaction chamber, and the relationship between gas flow velocity and plasma density was analyzed by the Langmuir probe detection equipment. Results show that the flow uniformity can significantly impact the plasma uniformity. Under the pressure of 6.5 Pa, the plasma density and flow velocity show a positive correlation, which is consistent with the experiment results in atmosphere pressure. This research verifies that improving the flow uniformity can enhance the plasma oxidation uniformity.

    • Yang Haijuan, Liu Cuirong, Zhang Wenbin, Li Yan

      2024,53(4):994-1001 DOI: 10.12442/j.issn.1002-185X.E20230019

      Abstract:With copper/steel composite pipe as research object, two-dimensional numerical simulation of explosive welding process was conducted through AUTODYN finite element software with SPH and ALE methods. The dynamic welding process and boundary effect were analyzed, and the explosive welding tests of copper/steel composite pipe were conducted. Results indicate that under the action of detonation waves, the composite pipe obliquely collides with the base pipe. The pressure in the collision zone remains stable at the order of 107 kPa, and a plastic deformation band appears near the collision zone. The shear stresses have opposite directions on the base pipe and composite pipe, and the interface morphology changes from straight line to wavy shape with the propagation of explosion wave. This result is consistent with the actual interface morphology of the T2/316L bimetal composite pipe in experiments, indicating that this finite element model can effectively simulate the explosive welding process of bimetal composite pipe. During the numerical simulation process, the dynamic parameter values at the edges are all smaller than the normal values, leading to boundary effects. Increasing the length of composite pipe and explosive can eliminate the boundary effect.

    • Jin Lan, Li Kaiqiang, Yi Tinghua

      2024,53(4):1011-1020 DOI: 10.12442/j.issn.1002-185X.20230552

      Abstract:In order to enhance the nano-cutting surface quality of Ni3Al-based alloy to obtain better service state, the nano-molecule dynamics (MD) simulation and micro-cutting experiment were combined to investigate the effect of loading temperature (300–1050 K) on cutting force and surface morphology. MD simulation results show that the fluctuation of cutting force is the smallest when the loading temperature is 750 K during nano-cutting process of Ni3Al-based alloy, compared with that at other temperatures. When the loading temperature is 600–750 K, the number of convex atoms affecting the surface morphology is the least, which indicates that Ni3Al-based alloy can achieve higher surface quality at loading temperature of about 750 K. The micro-cutting experiments of Ni3Al-based alloy show that higher flatness of the processed surface can be obtained at the loading temperature of 600–750 K, which indirectly verifies the feasibility of MD simulation results of the nano-cutting process of Ni3Al-based alloy. Results suggest that selecting appropriate loading temperature is an effective method to improve the nano-cutting surface quality of Ni3Al-based alloy.

    • Zhang Bo, Wang Guowei, Sun Mingyan, Qin Yu, Shen Xianfeng, Fang Hui, Wang Chao, Huang Shuke

      2024,53(4):1021-1031 DOI: 10.12442/j.issn.1002-185X.20230091

      Abstract:Gradient lattice structure is now commonly used as energy-absorbing components in aerospace, national defense and medical fields due to its excellent energy absorption ability when compressed. However, with the development of modern industry, the engineering field has put forward higher requirements on its compression properties. To make it further optimized, it is necessary to study the relationship between cell, structural parameters and compression properties. Therefore, in this study, two AlSi10Mg rod-diameter-change gradient body-centered cubic (BCC) and diamond (Diam) structures with different gradient gap were formed by selective laser melting (SLM) to investigate the effect of gradient gap on the compression properties, and to compare the two cells. The results of quasi-static uniaxial compression experiments and finite element analysis (FEA) show that the absorbed energy per unit volume increases significantly with the increase of gradient gap at the same relative density and with the same cell. The compressive modulus, yield strength, compressive strength and peak stress of Diam gradient lattice structure are higher than those of BCC when the gradient gap is the same, and its absorbed energy per unit volume and energy absorption efficiency are also higher than those of BCC.

    • Zhang Yunhua, Zheng Sen, Lou Diming, Fang Liang, Feng Qian

      2024,53(4):1032-1041 DOI: 10.12442/j.issn.1002-185X.20230131

      Abstract:Based on XRD, XPS, H2-TPR and other characterization methods and activity evaluation methods, the physical and chemical properties and catalytic activity of CDPF samples doped with different concentrations of La2O3 under hydrothermal aging condition were studied. The results show that with the increase of La2O3 doping concentration, the diffraction characteristic peak shifts a large angle and crystallinity of CDPF aging samples show a trend of decreasing then increasing. La2O3 doping can better inhibit the sintering and distortion of samples during hydrothermal processing and can effectively inhibit the reduction of active quantity, so that the concentration of Pt atoms on the surface of CDPF remains basically unchanged, and the degradation rate of CO, C3H8 and NO catalytic performance decreases. With the increase of doping concentration, the CDPF tends to reverse the trend of ageing.

    • Long Anping, Xiong Jiangying, Zhang Gaoxiang, Xiaolei, Feng Ganjiang, Guo Jianzheng, Liu Rutie

      2024,53(4):1042-1050 DOI: 10.12442/j.issn.1002-185X.20230064

      Abstract:The microstructure and mechanical properties of a novel Nickel-based powder superalloy FGH4113A under two heat treatment conditions were studied by means of scanning electron microscope (SEM), optical microscope (OM), tensile, creep and fatigue testing, providing the basis for dual microstructure heat treatment (DMHT). The results show that the supsolvus and subsolvus microstructure and mechanical properties have obvious dual-mode. At room temperature, the yield strength of subsolvus sample is 10.6% higher than that of supsolvus samples, and at 800 ℃, the yield strength of supsolvus samples is 11.7% higher correspondingly; The tensile strength of FGH4113A is better than that of ME3 and equivalent to that of LSHR. The creep deformation of FGH4113A alloy at 750°C/450MPa is dominated by the dislocation slip mechanism, and the dispersed small-sized borides conducive to improve the creep performance; FGH4113A has excellent creep properties, which is better than ME3 and equivalent to LSHR; The coarse-grain structure in the supsolvus sample has a longer slip band in crack propagation, resulting in lower cumulative damage under cyclic loading, and the crack growth resistance is better than that of subsolvus sample; The crack propagation fracture of the supersolvus sample is characterized by transgranular fracture. The existence of primary γˊ on the fine grain boundary reduces the crack growth resistance, and the fracture is rough, showing mixed fracture characteristics of intergranular and transgranular.

    • Li Tianyu, Wang Limin

      2024,53(4):1051-1057 DOI: 10.12442/j.issn.1002-185X.20230101

      Abstract:Fe-Ni based alloys are used in high temperature for a long time, so the microstructure stability at high temperature is one of the important indexes of the alloys. The microstructure and properties evolution of a new Fe-Ni based superalloy 21Cr-32Fe-41Ni at 750 ℃ for different aging time were investigated by scanning electron microscopy ( SEM ), transmission electron microscopy ( TEM ), electron probe microanalysis ( EPMA ) and chemical phase analysis. The results show that the precipitates in the alloy after long-term aging were mainly γ′, σ, α-Cr, MC phases. The weight percentage and size of the dispersed spherical γ′ in the matrix increased rapidly within 500 h aging. With the increase of aging time from 500 h to 2000 h, the weight percentage and size increase rate of γ′ gradually decreased. During the long-term aging process, the σ phases were distributed along the grain boundaries in block or strip shape, and within grains in needle or strip shape. The distribution of α-Cr phases in the grains was the same as that of σ phases. With the increase of aging time, the number of σ and α-Cr phases increased and they gradually coarsened. The σ phases with discontinuous distribution along the grain were gradually connected, and there was a tendency to develop into a network distribution. With the increase of aging time to 2000 h, the strengths of the alloy increased first and then decreased. They reached the peak after aging for 500 h. The hardness kept increasing.

    • SHI Peng, ZHANG Xianguang, SHU Chunyang, QI Jianghua, GUO Huangxun, CHEN Jiajun, YAN Jianhao, Kiyotaka Matsuura, PEI Yiwu

      2024,53(4):1065-1074 DOI: 10.12442/j.issn.1002-185X.20230744

      Abstract:In order to achieve precise control of the structure and precipitates during the rolling-cooling process of the high V, N micro-alloyed steel, the Gleeble-1500D thermal simulated test machine was used to study the thermal expansion curve and phase transformation rules of the experimental steel at different cooling rates after rolling. Especially, the dynamic continuous cooling transformation curve (dynamic CCT curve) of supercooled austenite, and the microstructure evolution behavior, microhardness and sensitivity of the nano-sized carbonitride precipitation behavior to the cooling rate were studied. The results show that when the cooling rate is lower than 3 °C/s, the microstructure of the experimental steel is composed of ferrite and pearlite. As for the cooling rate is 3 °C/s, bainite transformation occurs, and the matrix structure is composed by ferrite, pearlite and bainite. On the other hand, the pearlite structure is disappeared, and the martensite structure begins to be formed at the cooling rate of 8 ℃/s, and the matrix structure is composed of intergranular ferrite, bainite and martensite. When the cooling rate reaches 20 °C /s, the matrix structure is dominated by martensite and it is mixed with a small amount of proeutectoid ferrite and bainite. Furthermore, the cooling rate also has a significant influence on the precipitation behavior of nano-sized carbonitrides. When the cooling rate is within 1 °C/s, the diameter and number density of the nanoprecipitates in the polygonal ferrite show strong sensitivity to the cooling rate. The diameter of the nanoprecipitates is apparently decreased with the increase of cooling rate, and the it is inverse for the change in number density. When the cooling rate increases from 1 ℃/s to 3 ℃/s, the diameter of the nanoprecipitates further decreases, and the number density tends to be stable. As the cooling rate is further increased from 3 ℃/s to 5 ℃/s, the diameter of the nanoprecipitates keeps constant, and the number density is decreased. It was also found that less nanoprecipitates is contained in the bainite structure and the bainite is not helpful for the precipitation. Based on the above research on the structure evolution and precipitation law, a high V, N micro-alloy steel with a yield strength of more than 700 MPa and meeting seismic requirements has been industrialized and trial-produced.

    • ZHANG Can, WANG Guowei, ZHU Jingxi, WANG Lili, SHEN Xianfeng, YE Han, WANG Chao, HUANG Shuke

      2024,53(4):1075-1085 DOI: 10.12442/j.issn.1002-185X.20230104

      Abstract:In this paper, the effects of substrate preheating temperature on the microstructure and mechanical properties of AlSi9Mg1ScZr alloy samples prepared by selective laser melting were investigated. SLM samples were prepared at three different substrate preheating temperatures of 35°C, 85°C and 135°C and subjected to microstructure observation and property testing, respectively. The results showed that the substrate preheating temperature set to 135℃ caused the in-situ aging effect of the alloy during the printing process due to the combined effect of the substrate preheating temperature and laser scanning heat input, which promoted the precipitation of elements from the supersaturated solid solution while retaining fine dendrites and Si lattices. Compared to the sample with the substrate preheated at 35 °C, the nanoscale Mg2Si and Si phases precipitated significantly more in the α-Al matrix and dendrite boundaries, which served to improve the strength; however, the precipitation of the micron-scale Fe-rich phase had a negative effect on plasticity. At a substrate preheating temperature setting of 135°C, the prepared AlSi9Mg1ScZr alloy exhibited a yield strength of 360 MPa, a tensile strength of 502 MPa, and an elongation of 7% in the 0° direction, and a yield strength of 331 MPa, a tensile strength of 511 MPa, and an elongation of 5.4% in the 90° direction. In this study, the microstructure of AlSi9Mg1ScZr alloy prepared by SLM was improved by increasing the substrate preheating temperature and achieving in situ aging of the SLM samples during SLM, which significantly reduced the residual stresses and obtained ultra-high strength AlSi9Mg1ScZr alloy samples without subsequent heat treatment .

    • Zhong Zhihong, Yuan Dongli, Zhu Wenjing, Wei Renwei, Song Kuijing, Wu Yucheng

      2024,53(4):1086-1094 DOI: 10.12442/j.issn.1002-185X.20230011

      Abstract:Ag-Cu-Ti and Ag-Cu-Ti+B4C composite brazing alloys were successfully used to braze the B4C-TiB2-SiC-TiC (BTST) composite ceramic. The effects of brazing temperature and holding time on the interfacial microstructure and mechanical properties of the joints were investigated. The results show that Ag-Cu-Ti brazing alloy had a good wettability with BTST and Ti reacted with BTST to form TiC and TiB. The thickness of reaction layer increased with the increase of brazing temperature or holding time, and Ag-Cu eutectic alloy formed in the brazing seam. The bending strength of the joints increased with the brazing temperature or holding time first and then decreased. The addition of B4C into the Ag-Cu-Ti refined the microstructure of brazing seam and reduced the thickness of reaction layer. The maximum bending strength of the joint achieved was 314 MPa, when the BTST composite ceramic was brazed at 890℃ for 15 min using the Ag-Cu-Ti with 1 wt.% B4C.

    • Zhou Jian, Lin wenwen, Wei chengjia, Li huiru

      2024,53(4):1095-1102 DOI: 10.12442/j.issn.1002-185X.20230582

      Abstract:The Ti/IrO2-PbO2 anodes were prepared by thermal decomposition. The effects of sulfuric acid, nitric acid, hydrochloric acid, oxalic acid and hydrochloric acid/oxalic acid etching sequence on the performance of Ti/IrO2-PbO2 anodes were studied deeply. Surface morphologies, structure and electrochemical behavior of the titanium substrates with oxide-coated were investigated by field emission scanning electron microscope, X-ray diffraction, cyclic voltammetry, linear scanning voltammetry, electrochemical AC impedance spectroscopy and accelerated lifetime test. The results showed that dual-acid etching can obtain a better corrosion effect with a denser and more uniform surface structure compared to them of single-acid etching. The dual-acid etching achieved a complete TiHx crystal form. It can be beneficial to increase the coating loading and enhance the bonding force between the active layer and the substrate. The electrochemical properties of the anode were little determined by the order of double acid etching. The Ti/IrO2-PbO2 anode treated by oxalic acid followed by hydrochloric acid showed the best electrocatalytic activity and the longest accelerated lifetime.

    • Zhenghua Guo, Mingzhi Shi, Gangyao Zhao, Ranyang Zhang, Qingjie Wu, Xingzhou Wu, Shenlong Li

      2024,53(4):1103-1110 DOI: 10.12442/j.issn.1002-185X.20230068

      Abstract:In order to improve the forming quality of W-ring, the ultrasonic vibration rolling process of W-ring was studied in this paper. Based on ABAQUS/Explicit finite element simulation software, a three-dimensional finite element model of W-ring with ultrasonic vibration assisted rolling was established, and the influence of ultrasonic frequency on the non-uniform deformation of the ring was studied. The results show that with the increase of ultrasonic frequency, the stress unevenness of the ring increases first and then decreases. The strain unevenness of the ring component decreases slightly first, then increases sharply, and then decreases again. The non-uniformity of wall thickness decreases first, then increases and then decreases. When the ultrasonic frequency is 30kHz and 40kHz, the unevenness of the ring deformation increases significantly, which is caused by the wrinkle phenomenon of the ring. By analyzing the stress, strain and wall thickness of the section, it is proved that the position of wave crest and trough is the key position in the forming process.

    • Chen Weihao, Liu Fencheng, Niu Pengliang, You Qifan, Liu Fenggang, Wang Zhitai

      2024,53(4):1111-1119 DOI: 10.12442/j.issn.1002-185X.20230070

      Abstract:Given the high sensitivity of hydrogen porosity in the welding process of AlSi10Mg aluminum alloy formed by selective laser melting, a study was conducted to compare the effect of dehydrogenation treatment on the pore defects of alloy laser welded joints using solid solution dehydrogenation and vacuum solid solution dehydrogenation methods, under different states. The study analyzed pore distribution, microstructure evolution, and mechanical behavior of laser welded seam. The findings reveal that the solution treatment can effectively reduce the porosity of AlSi10Mg aluminum alloy laser welded seam formed by selective laser melting. Vacuum solution treatment has the best effect, reducing porosity from 2.64% of the deposited state laser welding seam to 0.14% of the vacuum solid solution state weld. The study explains the reasons for the appearance of pores, analyzes the evolution of the joint structure, and examines the change of the phase morphology and composition of the substrate. It is revealed that vacuum heat treatment is an effective method for pore formation, solving the problem of hydrogen gas in the weld due to the high content of hydrogen pre-existing in the substrate. After solid solution, the hardness of the base metal decreased significantly, and the average hardness of the welds of each test plate was 80HV, which was relatively consistent. The tensile strength of the welded joint of the solid solution test plate was 143MPa, which was lower than that of the deposited joint, but the elongation increased to 24%, characteristic of ductile fracture.

    • Fu Chuanqi, Lin Yongwei, Huang Yazhong, Li Shengjun

      2024,53(4):1130-1137 DOI: 10.12442/j.issn.1002-185X.20230063

      Abstract:Ni-Go composite coating was prepared on Q235 steel by electrodeposition. The effect of rare earth cerium on the morphology and properties of the composite coating was studied. The results show that when the cerium concentration is 0.8 g . L-1, the deposition rate of the composite coating increases to 7.142 g . dm-2 . h-1, the hardness reaches 608.8 HV, the wear amount is the smallest, the friction coefficient is the lowest, the self-corrosion potential Ecorr ( -0.3993 V ) is corrected, the corrosion current Icorr ( 3.258 . 10-6 A . cm-2 ) is the smallest, the corrosion rate is the lowest, and the corrosion resistance of the composite coating is the best. It was found that after the addition of rare earth cerium, the coral-like micro-sized convex polymer of the Ni-1.0GO composite coating became a small coral-like convex polymer with a smaller size, and the coating structure was significantly refined. When the cerium concentration is 0.8 g . L-1, the Ni-1.0GO-0.8RE composite coating has the best microstructure and the best performance. The main reason is that the rare earth cerium improves the dispersion ability of the particles in the plating solution and the cathodic polarization rate. The effect of increasing the precipitation potential of hydrogen ions at the cathode inhibits the occurrence of hydrogen evolution reaction, which further improves the performance of the composite coating.

    • Yiqian Wang, Yifan Su, Yuming Zhang, Cheng Zhang, Songsheng Lin, Mingjiang Dai, Zhipeng Sun, Qian Shi

      2024,53(4):1138-1148 DOI: 10.12442/j.issn.1002-185X.20230045

      Abstract:In order to expand the industrial application of diamond coating tool and improve the adhesive strength of diamond coating tool. In this paper, the “Acid-Murakami-Acid” (AMA) three-step pretreatment process for cemented carbide with different WC grain size of 0.2, 0.4, 1.0μm was systematically studied. The surface morphology of the pretreated substrate, cobalt content and coating morphology were analyzed by scanning electron microscope and EDS spectrometer. The phase structure of the coating was analyzed and characterized by Raman spectroscopy and X-ray diffraction spectroscopy. The scour resistance of the diamond coating was tested by dynamic impact experiments. These results showed that the acid treatment played an important role in removing Co. The smaller the grain size of WC, the longer the acid treatment time was required. The etching capacity of WC by Murakami treatment increased at first and then decreased, and the maximum Co exposure was reached at 3min. Therefore, the best pretreatment process of WC-6%Co (0.2, 0.4, 1.0μm) substates were determined. After the three-step method, the substates obtained uniform and compact diamond coatings with grain orientation of (111), excellent scouring resistance and great adhesion strength.

    • Jia Qiaorui, Wang Xiaohua, Liu Jie, Ma Shengguo

      2024,53(4):1149-1154 DOI: 10.12442/j.issn.1002-185X.20230087

      Abstract:In this paper, porous CoCrNi mesentropic alloys with porosity of 63%~78% and pore size of 1.3~2.2mm were successfully prepared by powder sintering and dissolution method. The pore morphology and phase composition of the samples were analyzed by SEM and XRD, and the axial quasi-static compression experiments were conducted on the samples. The results show that the elastic modulus and yield platform stress of porous CoCrNi alloy decrease with the increase of porosity and pore size. Compared with porosity, the effect of pore size on mechanical properties is low. The energy absorption values per unit volume of porous CoCrNi mesentropy alloys with different porosity range from 34.8 to 14.3MJ/m3 under dense strain, about 3.8 times that of aluminum foam, and the ideal energy absorption efficiency (I) of the five porosity ratios is close to 0.8, indicating that the porous CoCrNi mesentropy alloy has the potential to become an ideal energy absorption material.

    • Yuxuan Wang, Juntao Zou, Qiaoli Feng, Yunfei Bai, Junsheng Cheng, Lin Shi, Dazhuo Song, Lixing Sun, Yihui Jiang, Zhiwei Zhang

      2024,53(4):1155-1162 DOI: 10.12442/j.issn.1002-185X.20220981

      Abstract:The strength and elongation of Cu-14Sn-0.3Ti alloy were improved synergistically in this investigation by hot rolling+electric pulse treatment. The elongation of Cu-15Sn-0.3Ti alloy increased from 4.7% to 40%, and the strength increase from 298 MPa to 530 MPa after 70% hot rolling+10 min electric pulse treatment. The influence of deformation energy storage and pulse current on reduction of stacking faults and twin growth was investigated by adjusting hot rolling and electric pulse processing. The results show that the strength and density of Cu-14Sn-0.3Ti alloy increase with the increase of deformation energy storage. The δ phase dissolves, and the deformation-induced stacking faults reduced because of the synergetic effect of Joule heat and electron wind. After electric pulse treatment, the formation of twins provides additional slip systems for the movement of dislocations and improves the elongation of Cu-14Sn-0.3Ti alloy. On the one hand, the appearance of twins has divided and refined the grains. On the other hand, the formation of twin boundaries hinders the movement of dislocations during the deformation of Cu-14Sn-0.3Ti alloy, making the strength of Cu-14Sn-0.3Ti alloy improve.

    • Xu Kejun, Wang Liuying, Liu Gu, Ge Chaoqun, Wang Long, Wang Bin

      2024,53(4):1163-1169 DOI: 10.12442/j.issn.1002-185X.20230051

      Abstract:Electrochromic materials have very important application prospects in the fields of intelligent display and military camouflage. In order to improve the long response time and poor cycling stability of NiO film in alkaline electrolyte, strontium doped nano-sheet NiO electrochromic films were prepared by hydrothermal method. The lattice distortion caused by ion doping and the synergy of micro-nano structure make NiO thin films exhibit excellent electrochromic properties. Strontium ion doping improves the electrochemical characteristics of NiO film, thus improving the electrochromic response time (coloring time is about 4.5 s, bleaching time is about 2.7 s), and improving the coloration efficiency (CE, 85.2 cm2C-1). On the other hand, it provides support for the NiO crystal structure, strengthens the stability of the crystal structure in the electrochromic process, and significantly improves the cycle stability of the film (the cycle number exceeds 10000). The research results of this paper have certain reference and guiding significance to promote the engineering application of electrochromic materials.

    • >Reviews
    • Zhou Huimin, Huang Xuqiang, Kong Lingfei, Chen Jianxin, Gao Fei, Liu Shaohong, Chen Minfang, Zhang Jin, Tie Di

      2024,53(4):1170-1180 DOI: 10.12442/j.issn.1002-185X.20230132

      Abstract:The research progress of the corrosion behavior of magnesium alloy in the marine atmospheric environment was reviewed and summarized in this present literature. The current research progress was concluded, and some perspectives on future research directions were given. In the marine atmospheric environment, the electrochemical reaction of magnesium alloy under the coating of thin electrolyte layer on the surface is prone to localized corrosion, and is also susceptible to the influence of environmental factors. Compared to the inland atmospheric environment, the marine atmosphere is rich in aerosol particles, which promote serious pitting corrosion of magnesium alloys. Higher relative humidity can increase the thickness of thin electrolyte layer, resulting in higher atmospheric corrosion rate of the alloy. Meanwhile, the atmospheric corrosion rate of magnesium alloy increases linearly with the increase of temperature. CO2 in the air can inhibit the erosion of NaCl on magnesium alloys. Future research in this field may focus on the revelation of corrosion mechanism in specific environment and the synergistic effect of various environmental factors on corrosion behavior, so as to guide the design and preparation of marine magnesium alloy materials.

    • Zhao Jin, Ji Xiaoliang, Jia Qiang, Wang Yishu, Guo Fu

      2024,53(4):1181-1194 DOI: 10.12442/j.issn.1002-185X.20230067

      Abstract:The development of miniaturized and multifunctional electronic products makes the devices face problems such as thermal damage and substrate warpage during the packaging and assembly process. In order to reduce the thermal impact of electronic packaging and assembly processes on chips and devices, low melting point interconnect materials need to be researched and developed. Tin-bismuth (Sn-Bi) alloy solder has received considerable attention due to its low melting point, low cost, good wettability and mechanical strength, but the segregation of the brittle Bi phase is detrimental to the long-term service reliability of the devices. By adding alloying elements to the Sn-Bi solder to form a Sn-xBi-yM alloy solder, the service reliability of the Sn-Bi alloy solder and its solder joints can be effectively improved. This paper analyzes and summarizes the effects of different alloying elements on the melting point, wettability, microstructure, mechanical properties, interfacial reaction and reliability of Sn-Bi solder from the perspective of solder alloying. And based on the existing research results, the future development direction of Sn-Bi alloy solder is prospected.

    • Zhao Yanchun, Lv Zhi, Ma Huwen, Shi Yapeng, Mao Feng, Kou Shengzhong, Duan Wangchun, Feng Li

      2024,53(4):1195-1206 DOI: 10.12442/j.issn.1002-185X.20230127

      Abstract:The strength-plastic inversion generally exists in the traditional metals with uniform or random microstructure, while the gradient nanostructured metals exhibit excellent comprehensive mechanical properties due to the gradient change of grain size and the coordination of different characteristic sizes during deformation. In recent years, the design theory, preparation method and deformation mechanism of the heterostructures composed of heterogeneous regions with different properties have been gradually improved. In this paper, the classification and preparation methods of heterostructure metals, such as gradient structure, bimodal structure, harmonic structure, heterogeneous layered structure, dispersed nano-domain and layered nano-twin structure, are summarized. Combined with the non-uniform plastic deformation behavior of gradient nanostructured metal during stress loading, the strengthening and toughening mechanisms of gradient nanostructured metal are summarized, including gradient plasticity, geometrically necessary dislocation, mechanically driven grain coarsening, surface residual stress, surface disturbance and shear band behavior, and the challenges faced by its future development are discussed.

    • Jiayanmin, GuoDi

      2024,53(4):1207-1216 DOI: 10.12442/j.issn.1002-185X.20230086

      Abstract:The precise monitoring of humidity is related to the preservation of some deliquescent materials, the measurement accuracy of electronic instruments and other aspects. High-performance humidity sensors have a wide range of uses in modern industry, agriculture, and medicine. Humidity sensitive materials include dielectric materials, semiconductor materials, metal materials, etc. As a special kind of dielectric material containing spontaneous electrodes, the application of ferroelectric materials in the field of humidity-sensitive sensors is receiving increasing attention. Theoretically, the electrodeposition of ferroelectric materials has a strong adsorption effect on the polar water molecules on the surface, and at the same time, the polar water molecules attached to the surface can in turn affect the ferroelectric polarization, dielectric and electrical impedance properties of ferroelectric materials. Therefore, ferroelectric materials have important application prospects in high-performance wet-sensitive sensor devices, and ferroelectric wet-sensitive materials have the advantages of high sensitivity, fast response, and good stability. This paper reviews the development history and status of ferroelectric moisture-sensitive materials, and summarizes in detail the physical mechanism of humidity sensing by ferroelectric materials. The ferroelectric moisture-sensitive materials are classified into four major parts, namely, ferroelectric nano, ferroelectric ceramic, ferroelectric thin film, and ferroelectric single crystal, according to their categories and properties, and the research progress of their moisture-sensitive properties and various factors affecting the moisture-sensitive performance are reviewed respectively, in order to provide some scientific references for the future research of moisture-sensitive of new ferroelectric materials.

    • Wu Shiliang, Wang Haitao, Wang Sujuan

      2024,53(4):1217-1228 DOI: 10.12442/j.issn.1002-185X.20230136

      Abstract:In recent years, with the development of refractory metal research, the traditional process can not meet the demand of refractory metal and its complex structure. In view of the high melting point and excellent high temperature mechanical properties of refractory metal materials, combining them with laser additive manufacturing technology will provide greater elasticity and machinability in refractory metal design. In this paper, we summarize the laser additive manufacturing technology of refractory metal materials. According to material classification, tungsten alloy, porous tantalum, molybdenum alloy and refractory high entropy alloy are reviewed. Because refractory metals manufactured by laser additive are sensitive to low melting point elements and processing parameters, we conclude the influences of these factors on process control and final part quality. Finally, including the advantages and disadvantages of the current research are, and the future development trend is prospected.

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    • Ren Lina, Zhang Qunbing, Lei Xiao Wei, Yang Jia Dian, Zhang Jian Xun

      Available online:May 07, 2024  DOI: 10.12442/j.issn.1002-185X.20240084

      Abstract:In this paper, different laser heat input conditions were designed to weld TC17 titanium alloy. Optical microscopy, scanning electron microscopy, transmission electron microscopy, tensile and fatigue tests were used to compare the macroscopic morphologies, microstructures, and mechanical properties of the welded joints. The results show that with the increase of heat input, the morphology of weld changes from Y to X type. The number of pore defects in the weld increases first and then decreases. The pore defects are mainly distributed in the middle and lower part of the weld zone. The weld is comprised of coarse columnar grains with strip dendrites inside, and the spacing of dendrite increases gradually with the increase of heat input. The heat affected zone comprises finer equiaxed grains, and the increase of heat input leads to the refinement of α phase and coarsening of β phase. Moreover, the TC17 laser welded joints all fractured in the weld zone in the mechanical tests. Under the influence of dendrite size, the tensile strength decreases with the increase of heat input. The welding pore is the main reason for the fatigue fracture, and the fatigue life peaks when the number of pore defect is the lowest.

    • Chen Shuang, Yang Yanhong, Liang Jingjing, Li Jinguo, Zhou Yizhou

      Available online:March 25, 2024  DOI: 10.12442/j.issn.1002-185X.20230813

      Abstract:Defects such as cracks and micropores existed in nickel-based superalloy during laser powder bed fusion (LPBF), hindering their application in various fields. In this paper, hot isostatic pressing was combined with conventional heat treatment to obtain LPBF nickel-based superalloy parts with fewer defects and ideal properties. The hot isostatic pressing process improved the densification, and the conventional heat treatment changed the micro-defects to improve the mechanical properties. After HIP treatment, the defect volume fraction of LPBF specimens decreased to 0.0132%, after HT treatment, the HIP+HT specimens defect content rebounded to 0.0252%. After post-treatment, the hardness showed a decreasing trend, and the tensile strength and elongation at break of HIP+HT specimens increased by 32.2% and 474.7%, respectively, at room temperature.

    • zhangyongdi, zhaolisong, dailuyu, yangguang

      Available online:March 25, 2024  DOI: 10.12442/j.issn.1002-185X.20240055

      Abstract:The loading conditions of human bone in daily activities are complex. In order to obtain porous titanium alloy with excellent comprehensive performance for bone implants, it is necessary to comprehensively evaluate the different mechanical properties of porous structures. According to the different loading forms of human bones, the porous structures (TO-C, TO-T, TO-B) under compression, torsion and bending loads were designed by topology optimization method, and the obtained structures were reconstructed. The different mechanical properties of three topologically optimized porous structures were studied by finite element simulation of compression, torsion and bending. Finally, the compression specimens were prepared by Selective Laser Melting (SLM) technology, and the compression test was carried out. The results show that the TO-B structure has the best comprehensive mechanical properties among the three structures, and the compressive strength and compressive elastic modulus meet the needs of human bone implantation, which is the best porous structure type for orthopedic implants.

    • Fan Yunpeng, Zhao Xinbao, Zhou Yu, Xia Wanshun, Yue Quanzhao, Gu Yuefeng

      Available online:March 22, 2024  DOI: 10.12442/j.issn.1002-185X.20230787

      Abstract:Directionally solidified superalloys are widely used in industrial gas turbines and other advanced power propulsion system turbine blades and other components due to their excellent high-temperature strength, corrosion and oxidation resistance, good structural stability and casting properties. Directionally solidified superalloys for gas turbines have developed from the first generation to the fourth generation by adjusting the proportions of different solid solution strengthening, precipitation strengthening and grain boundary strengthening elements. Its intragranular structure are mainly composed of γ phase and γ? phase. There are carbides, borides and other precipitated phases at the grain boundaries that can pin in the grain boundaries. Under the joint influence of these strengthening phases, nickel based directionally solidified superalloys have better tensile properties and creep properties that change with temperature. This article combines the current application status of directional solidification superalloys in gas turbines, starts with the composition characteristics and organizational structure characteristics, further analyzes its performance characteristics, and looks forward to future research on directional solidified superalloys.

    • Zang Ximin, Zhao Guangdi, Wu Jinjiang, Jiang Haoyuan, Yao Xiaoyu

      Available online:March 22, 2024  DOI: 10.12442/j.issn.1002-185X.20230790

      Abstract:To improve the hot workability of hard-deformed superalloy U720Li, the effect of holding time before deformation (5 min and 10 min) on its hot deformation behavior was investigated using hot compression tests. The flow stress increases with increase of strain rate, while decreases with increase of deformation temperature and holding time. Based on the obtained Arrhenius-type constitutive models, the calculated peak stresses are in good agreement with experimental values, and the deformation activation energies for the holding time of 5 min and 10 min were calculated to be 992.006 kJ·mol-1 and 850.996 kJ·mol-1, respectively. Moreover, processing maps of U720Li alloy at these two holding time were constructed. Through observation of deformation microstructures in each domain of the processing maps, the optimal hot working conditions for the holding time of 5 min were determined to be 1090~1110 ℃/1~10 s-1 and 1146~1180 ℃/1~10 s-1, while those for the holding time of 10 min were 1080~1090 ℃/1~10 s-1 and 1153~1160 ℃/1~10 s-1. This indicates that the “safe” processing window can be obviously enlarged by shortening the holding time reasonably. In the absence of cracking, the dynamic recrystallization (DRX) grain size increases gradually with increasing deformation temperature and holding time, but it first decreases and then increases with the increase of strain rate. When the deformation temperature is below 1100 °C, the DRX mechanism is mainly the particle-induced continuous dynamic recrystallization (PI-CDRX). But as the temperature was raised to above 1130 °C, the main DRX mechanism changes to discontinuous dynamic recrystallization (DDRX).

    • Lao Zhenhong, Zhang Haoyu, Wang Shengyuan, Cheng Jun, Tan Bing, Zhou Ge, Zhang Siqian, Chen Lijia

      Available online:March 22, 2024  DOI: 10.12442/j.issn.1002-185X.20230791

      Abstract:To study the relationship between the microstructure and tensile properties of the novel metastable β titanium alloy Ti-5.5Cr-5Al-4Mo-3Nb-2Zr, a heat treatment process of ABFCA (α+β annealed with subsequent furnace cooling plus aging treatment) was designed, which can precipitate α phases of different sizes in the β matrix. The microstructure obtained by this heat treatment process is composed of a primary α (αp) phase, submicro rod-like α (αr) phase and secondary α (αs) phase. The results show that the alloy with multiscale α phase has an excellent balance of strength-ductility. The elongation (EL) is ~18.3% at the ultimate tensile strength (UTS) of ~1125.4 MPa. In this experiment, the relationship between the strength of the alloy and the α phase is established. The strength of the alloy is proportional to the power of -1/2 of the α phase average spacing and width. The αs phase with a smaller size and phase spacing can greatly improve the strength of the alloy by hindering dislocation slip. The transmission electron microscopy analysis shows that there is a large amount of dislocation accumulation on the α/β interfaces, and many deformation twins were found in the αp phase after tensile deformation. When the dislocation slip is hindered, twins occur at the stress concentration, and twins can initiate some dislocations that are difficult to slip. Meanwhile, the plastic strain is distributed compatibly among the αp, αr, αs phase and β matrix, thereby enhancing the ductility of the alloy. The ABFCA heat treatment process proposed in this study provides a reference for the heat treatment of metastable β titanium alloys, and this study has made a modest contribution to the development of titanium alloys.

    • Xie Jing, Xie Wangnan, Sun guodong, Li Hui, Jia Yan, Zhao Peng

      Available online:March 22, 2024  DOI: 10.12442/j.issn.1002-185X.20230794

      Abstract:Yttrium stabilized zirconia (YSZ) powder was synthesized by hydrothermal method using yttrium nitrate hexahydrate and zirconium oxychloride as yttrium and zirconium sources, respectively. YSZ bulk material was prepared by discharge plasma sintering (SPS) method using self-made YSZ powder as raw material. The effects of sintering temperature and pressure on the microstructure, Vickers hardness, fracture toughness and other mechanical properties were studied. The results show that pure YSZ powder can be obtained by hydrothermal method when the content of yttrium is 10 %. With the increase of SPS temperature and pressure, the density of YSZ block material gradually increased, and YSZ block with a porosity of only 2.6 % was prepared at 1400 ℃/50 MPa. With the increase of sintering temperature, the Vickers hardness and nano-hardness of the material first increase and then decrease, while the elastic modulus will increase accordingly. With the increase of sintering pressure, the mechanical properties of the material will be improved, and the maximum value will be reached at 1400 ℃/50 MPa. The Vickers hardness, nano-hardness and elastic modulus are 13.11±0.2 GPa, 15.67±0.21 GPa and 350.43±6.19 GPa, respectively. The fracture toughness decreases first and then increases with the increase of sintering temperature, and decreases with the increase of sintering pressure, reaching the maximum at 1400 ℃/20 MPa, which is 5.4±0.27MPa·m1/2。

    • Wei Li, Yao Jian, Zhang Jianting, Sun Haohua, Li Yanqing, Xiao Lei

      Available online:March 22, 2024  DOI: 10.12442/j.issn.1002-185X.20230798

      Abstract:The TLP welding test of DD5 Ni-based single crystal supperalloy was carried out under welding conditions of 1280 ℃/12h/0.01 MPa using the self-developed transient liquid phase bonding (TLP) interlayer material. The microstructure and precipitates of the welded joint were analyzed using SEM and the thermodynamic software Jmatpro. The results showed that the thickness of the interlayer had a significant impact on the microstructure of the welded joint. When the thickness of the interlayer was 120 μm, the microstructure and composition of the weld and the base metal tend to be consistent, and no obvious brittle precipitates are formed in the weld zone γ" Phase and matrix γ" The combination is basically complete; When the thickness of the interlayer is 160 μm and 200 μm, the ASZ is composed of brittle phases such as sunflower like eutectic structure, fishbone like borides, and block carbides rich in Ta and Hf. After PBHT, the γ" square degree of weld zone is significantly improved, and the size is basically consistent with the substrate. The Stress rupture test was conducted under the condition of 980 ℃/248MPa, When the thickness of the intermediate layer is 120 μm, the stress rupture life can reach 145.54h. And the results showed that as the thickness of the intermediate layer increased, the stress rupture life of the joint continued to decrease, and the fracture mode changed from ductile fracture to brittle fracture.

    • Ma Danrui, Guo Jing, Zhang Maicang

      Available online:March 22, 2024  DOI: 10.12442/j.issn.1002-185X.20230799

      Abstract:In this paper, two kinds of Ni-base alloys (alloy A and alloy B), which are alternative materials for superheater and reheater tubes of ultra-supercritical power station applications under high parameters, are systematically investigated including the phenomenon of grain boundary widening, the kinetics of the grain boundary widening process and the evolution mechanisms of this phenomenon. The results show as follows, the main precipitates in the widening grain boundary region are M23C6 carbide and the γ" phase. And the evolution of grain boundary broadening of A, B alloys with aging time follows the JMAK equations. The formation process of the widening grain boundaries is consist of three stages: first, the M23C6 carbides near the grain boundaries dissolve back inducing the coarsening of the M23C6 carbides at the grain boundary and the grain boundary migration; secondly, new M23C6 carbides are precipitated in the grain boundary migration area, and the M23C6 carbides in the grain boundary area are arranged in multiple layers; Thirdly, the γ" phase will precipitate at the M23C6 /γ interface with the decreasing coarsening rate of carbides at grain boundary, and the γ" phase will get bigger by short-circuit diffusion, resulting in the grain boundary widening to a great extent.

    • XU Zhao-Ying, SU Yong-Yao, ZHANG Teng-Fei, WANG Jin-Biao, Qiaowang Chen

      Available online:March 22, 2024  DOI: 10.12442/j.issn.1002-185X.20230805

      Abstract:In this paper, based on the concept of surface engineering and composite multi-component structure design, the titanium doped DLC films with different acetylene gas flow rate were prepared on titanium alloy threaded fasteners by microwave ECR enhanced magnetron sputtering technology. The microscopic morphology of titanium-doped DLC films were analyzed by transmission electron microscopy. The structure, residual stress, hardness, adhesive force and wear properties were studied by XRD, profilometry technique, nanoindenter and friction test. The results showed that nanometer TiC crystalline grains was formed in titanium-doped DLC films, and the residual stress of titanium doped DLC film can be effectively reduced by suitable acetylene gas flow rate. The sp3 hybrid bond content decreases gradually with the acetylene flow rate increasing. The titanium doped DLC film with acetylene gas flow rate of 25 sccm had higher hardness elastic modulus and toughness, and can resist the scratch of the indenters, excellent toughness and crack deformation resistance, had the best adhesion strength and wear resistance due to the high H/E and H3/E2 ratios, which can effectively improve the service life of titanium alloy fasteners. The results have certain reference value and theoretical basis for the preparation and application of high-hard wear resistance composite film on titanium alloy threaded fasteners.

    • Qu Zhehao, Feng Wei, Gao Chunlai

      Available online:March 22, 2024  DOI: 10.12442/j.issn.1002-185X.20230809

      Abstract:The solution enthalpy and the excess entropy of Zr in αU have been calculated based on first principles calculations in order to achieve U-rich solubility curves for U-Zr phase diagram. The enthalpy and the excess entropy of the Zr atom corresponding to Zr-αU transforming from solution state into δUZr2 are 1.437 eV/Zr atom and 1.060 kB/Zr atom by using the SQS model, which are 1.420 eV/Zr atom and 0. 732 kB/Zr atom with the disorder structure for δUZr2. But based on the experimental data, the fitted solution enthalpy and excess entropy are -0.823±0.712 meV/Zr atom and 5.880±9.976 kB/Zr atom, respectively. Through comparing the theoretical calculations and the experimental fitting results, it is found that the effect of the vibrational entropy on solubility could not be ignored. This discrepancy between the theoretical results and the experimental data might be related to the fact that the positions of Zr in δUZr2 in the theoretical calculations are not well consistent with the specific structural parameters of the the experimental samples.

    • Jiahui Wang, Xinbao Zhao, Quanzhao Yue, Fangjie You, Wanshun Xia, Yuefeng Gu, Ze Zhang

      Available online:March 22, 2024  DOI: 10.12442/j.issn.1002-185X.20230811

      Abstract:The recent progress and future prospects for ultra-centrifugal sedimentation in solids are described in this article, mainly for equipment, miscible systems and compounds. Almost 90% ultracentrifugation experiments have been performed on the 1st and 2nd high-temperature ultracentrifuge which typically operate at temperatures below 500 ℃ and maximum centrifugal acceleration up to 1,000,000 g. The strong gravitational and temperature fields induce atomic-scale graded structure, grain growth and refinement, voids accumulation caused by the atomic sedimentation in miscible systems, while new structures, properties and substances are produced in some compounds. A new cantilever high-temperature ultracentrifuge with a temperature of up to 1200 ℃ is under construction at Zhejiang University, making it possible to simulate the composition, microstructure and property evolution of superalloys in the operating environment of aircraft engines.

    • Bin Yuan, Qiaoli Lin, Cong Ni, Likai Yang

      Available online:March 22, 2024  DOI: 10.12442/j.issn.1002-185X.20230812

      Abstract:Multi-metal composites can integrate the properties of a single component to obtain the high perforcemance and multifunctions that are difficult to be achieved by the conventional methods, which have promising application prospects. Here, it was proposed a novel approach to prepare lamellar multi-metal composites by selective laser melting and vacuum melt infiltration technology. Using Cu/316L as a model material, successfully prepared composites with delicate lamellar structure, investigated the effect of configuration variations on the properties of the composites. The results show that the properties of the lamellar composites are significantly anisotropic. With the increase of the thickness of the 316L layer, the compressive strength and the elastic modulus of the composites increase, and the electrical conductivity slightly decreases, reaching 1.96, 1.34, and 0.9 times of that of pure copper, respectively. Owing to the structural optimization (micron-scale laminations) and component selection (copper and stainless steel), the composites possess both outstanding toughness and good electrical conductivity. Moreover, the methodology provided in this work is novel and universal, providing a new approach for the design and preparation of high-performance and multifunctional composites.

    • Yao BIbo, Peng Yuyang, Li Zhenhua, Liu Meihong, Li Hai, Wang Cong

      Available online:March 22, 2024  DOI: 10.12442/j.issn.1002-185X.20230818

      Abstract:Increasing the layer thickness can significantly improve the preparation efficiency of selecting laser melting formed Ti-6Al-4V. However, it leads to lower forming quality in comparison to low layer thickness. Annealing heat treatment can improve the ductility of titanium alloy prepared by selective laser melting, but the effect of annealing heat treatment on the sample with high layer is not clear. The Ti-6Al-4V with high layer thickness was fabricated by selective laser melting. The 700 ℃ and 950 ℃ were set as annealing heat treatment temperature, and the effects of heat treatment on the microstructure and properties of Ti-6Al-4V were investigated. The results reveal that the preparation of samples can achieve good forming quality when the scanning speed ranges from 600 mm/s to 800 mm/s. After annealing at 700 ℃ and 950 ℃, the microstructure of the sample transforms from acicular martensite to lath martensite. The β phase can be observed after heat treatment at 950 ℃. The changes in compression performance are influenced by the microstructure. The ultimate compressive strength of the prepared sample with a scanning speed of 600mm/s is 1593MPa, and the maximum fracture strain is 15.1%. After annealing heat treatment, the ultimate compressive strength decreases to 1359MPa and the maximum fracture strain increases to 22.2%. The fracture mode changes from brittle fracture to ductile-brittle fracture.

    • Sun Ruochen, Mi Guangbao

      Available online:March 22, 2024  DOI: 10.12442/j.issn.1002-185X.20230822

      Abstract:The high temperature fire retardancy of titanium alloy is an important factor restricting its application in aeroengine, while the laser ignition method can accurately reflect the fire retardancy of titanium alloy under local heating. Due to the limitations of laser ignition experiments on the microscopic boundary of the temperature field and the transient propagation mechanism of the temperature field, Molecular Dynamic (MD) simulations and JMatPro calculation are applied in this paper to study the temperature field of Ti-6Al and Ti-48Al. The obtained results show that a molten pool is formed on the surface of Ti-Al alloys under continuous laser irradiation, and the temperature field of the molten pool is normally distributed from the center to the edge. When the center temperature reaches the critical point of ignition, the extended combustion occurs, and the extended combustion path advances along the direction of the air flow. Compared with Ti-6Al, Ti-48Al alloy has higher fire retardancy under laser ablation. This is due to the higher heat transfer performance of Ti-48Al, which leads to the weakening of the heat concentration effect near the boundary of the spot temperature field. So it is necessary to increase the partial pressure of oxygen, and then reduce the ignition point of the alloy in order to achieve the ignition boundary condition of Ti-48Al alloy under the same laser heat source. In the aspect of extended combustion path, the boundary heat collection effect of specimens shown by MD models reveal another mechanism affecting combustion expansion path besides the direction of airflow. That is, the heat generated by the laser spot is interrupted when it is transmitted to the boundary of the specimen along the short side direction, resulting in a concentration of heat near the boundary. So the combustion path also tends to expand along this direction.

    • Zheng Yongfeng, Hu Xiaofeng, Yang Zhirong, Jiang Haichang, Rong Lijian

      Available online:March 22, 2024  DOI: 10.12442/j.issn.1002-185X.20230827

      Abstract:The ultra clean 30Cr2Ni4MoV rotor steel has the advantages of high strength, good toughness and excellent performance stability, which is widely used in the manufacture of low pressure rotor and spindle of high-power steam turbine and so on. As a microalloying element, the addition of V element to the 30Cr2Ni4MoV steel will precipitate alloy carbides and refine grain, which can achieve an excellent combination of strength and toughness. However, the effect of V content on the strength and toughness as for ultra clean 30Cr2Ni4MoV rotor steel has not been reported. In this work, the effects of V content (0.1, 0.2%, mass fraction) on the carbide evolution and mechanical properties of ultra clean 30Cr2Ni4MoV rotor steel with different heat-treatment states (as tempered and as step cooled) were investigated by SEM, EBSD, XRD, TEM, and APT. The results show that both tempered steels show lath martensite microstructure. The increasing of V content has no obvious effect on the carbide type (M23C6, M2C and MC) and size, but promotes the precipitation of more and finer V-riched carbides MC, which refines the prior austenite grain size of the 0.2V steel. The refinement of grain size and precipitation of finer MC carbides increase the yield strength of the 0.2 V steel by 147 MPa through grain refining strengthening and precipitation strengthening, respectively. After step cooling heat-treatment, the microstructures and the type of carbides in two experimental steels remain stable and the size of carbide grows slightly. After the step cooling heat-treatment, the yield strength of both steels show a slight decrease due to the carbide coarsening. As for 0.2V steel, the mobility of dislocations decreases due to precipitation of more MC carbides, which induces the decrease of the critical stress σf of crack propagation promotes the tendency of crack initiation and propagation. Therefore, as compared with 0.1V steel the FATT of 0.2V steel increases by 21°C.

    • Ning Zhaoyong, Xin Shewei, zhou wei, Wang Xiao

      Available online:March 22, 2024  DOI: 10.12442/j.issn.1002-185X.20230828

      Abstract:The microstructure of Ti-1500 alloy in three different deformation zones at different hot upsetting temperatures was comparatively analyzed through hot upsetting experiments. The experimental results show that the hot upsetting process has a significant influence on the microstructure evolution, and the higher the hot upsetting temperature and the larger the deformation, the more obvious the regional dynamic recrystallization is. Specifically, dynamic recrystallization did not occur in deformation zone I and deformation zone II at 700 ℃, but obvious recrystallization occurred in deformation zone III, α→β phase transformation occurred at 820 ℃ and obvious dynamic recrystallization occurred in all three deformation zones, and the recrystallized grains grew excessively at 900 ℃. When upsetting at 700 ℃, the {001}//ND texture was formed in the deformation zone I. With the increase of deformation, the grains in the deformation zone II gradually turned in the directions of <001> and <111>, and finally the {001} texture with higher strength and more volume fraction was formed and a part of the {111}//ND texture was formed. When the deformation amount increased to the deformation zone III, During grain growth, the grain boundaries of <001> oriented grains migrate to those of <111> oriented grains, which leads to the further increase of {001} texture strength and volume fraction, while the volume fraction of {111} texture decreases, and the texture type, texture strength and texture evolution law at 820 ℃ and 900 ℃ are consistent with those at 700 ℃.

    • zhangjingang, Liuxinling, chenxing, lizhen, lileyu, liuchangkui

      Available online:March 22, 2024  DOI: 10.12442/j.issn.1002-185X.20230834

      Abstract:Low cycle fatigue crack initiation behavior of nickel based single crystal superalloy at 530 °C have been investigated. The behavior of crack initiation is closely related to the maximum strain. When the maximum strain is 2.0%, the fatigue crack is originated at the position of persistent slip bands on the surface of specimen, where is located at the {111} slip plane. No defects are observed at the crack initiation position. When the maximum strain is lower than 1.6%, the cracks are initiated in the casting defects at subsurface or internal of the specimen. The casting defects is located in the {100} slip plane of the vertical axial force. The crack was initiated along the {100} slip plane and then expanded along different {111} slip plane after a short stage of expansion. As the maximum strain decreases, the position of crack initiation gradually changes from the surface to the interior. Moreover, the secondary cracks extending inward along the fracture surface in the crack initiation area, and there is obvious stress concentration near the secondary crack. The dislocation density is high near the fracture surface in the crack initiation zone, where existed a lot of dislocations cut into the γ" phase. An oxide layer of approximately 50 to 100nm was presented on the fracture surface, and Ni and Co elements are mainly segregated into the oxide layer of the surface.

    • Xuyangtao, Pengyin, Duhaiyang, Liyanhong, Zhongzhiqiang

      Available online:March 22, 2024  DOI: 10.12442/j.issn.1002-185X.20230839

      Abstract:This study investigates the effect of different concentrations of lanthanum chloride (Ce2(SO4)3) on the grain refinement of nickel deposition layers during the electrochemical deposition process in industrial electrolytes. The impact of different (Ce2(SO4)3) concentrations on nickel electrodeposition behavior was analyzed using the Liner sweep voltammetry curve (LSV), Cyclic voltammetry curve (CV) and Chronoamperometry curve (CA). The microstructure morphology and grain size of the deposition layers were analyzed u-sing scanning electron microscopy and the preferred orientation and crystal structure were analyzed using X-ray diffraction. The results show that the addition of different concentrations of (Ce2(SO4)3) to the industrial electrolyte leads to a negative shift in the starting deposition potential of nickel, an increase in cathode polarization degree, an increase in overpotential, a shortened nucleation relaxation time tm and an accelerated nucleation rate during nickel electrodeposition, resulting in grain refinement of the deposition layers.

    • Chen Yu, Wang Wentao, Wu Yun, Han Leilei, Wang Ming, Chen Jiajun, Zhao Yong

      Available online:March 22, 2024  DOI: 10.12442/j.issn.1002-185X.20240041

      Abstract:REBa2Cu3O7-x high-temperature superconducting coated conductors (CCs), i.e. the second generation high-temperature superconducting tapes, with excellent current carrying properties and mechanical behaviors, are potentially applied in the fields of power, transportation, medical care, and military, receiving extensive attention from superconductor research teams at home and abroad in recent years. Increasing the thickness of the superconducting layer in CCs is facilitated to enhance the superconducting current transmission capability and increase the engineering critical current density, thus being one of the major routes to reduce the cost of CCs. The “thickness effect”, i.e. critical current density (Jc) decrease with the increase of film thickness, mainly hinders the fabrication of high-quality superconducting thick films. This article introduces the preparation methods and epitaxial growth mechanism of YBCO thick films, discusses various factors that affect Jc and main ways to improve Jc, and summarizes the latest research progress in YBCO thick films by major international teams.

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    Rare Metal Materials and Engineering
    2024,Volume 53, Issue 4
    Editor in chiefPingxiang Zhang
    Associate editorYingjiang Shi
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