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Editors' Note
Amorphous alloy is a disordered alloy developed by rapid solidification technology and entropy control concept. It has disordered composition and long-range disordered structure, and has the properties of glass, metal, solid and liquid. The unique composition ratio and microstructure of high entropy alloy introduce excellent properties beyond those of traditional alloys. Their structure is ordered but the composition is disordered. The multiple characteristics result in multiple mechanisms during deformation, leading to excellent performance in mechanical properties, thermal stability, corrosion resistance, magnetic properties, etc., which has broad application prospects. As new metal materials integrating structure and function, amorphous alloy and high entropy alloy have shown great significance and strategic value in basic research and technical application. The development of disordered alloys provides unlimited possibilities to break through the performance limits of traditional alloys.
This special issue brings together the research results from the University of Lyon in France, the Polytechnic University of Catalonia in Spain, the Northwestern Polytechnical University in China, and other universities, covering the research direction of the physical, chemical, and mechanical properties of high entropy alloys and amorphous alloys. Guest editor-in-chief of this special issue, Professor Jichao QIAO, doctoral supervisor of Northwestern Polytechnical University, China, is funded by the Shaanxi Outstanding Youth Science Fund project and selected as the Shaanxi Hundred People Program (Youth Project). For a long time, he is devoted to the research of the dynamic relaxation mechanism, stress relaxation and creep of metal glass and other physical and mechanical properties. It is expected that this special issue can become a platform for experts and scholars in the field of disordered alloys to share research results and to exchange academic ideas, helping the development and progress of disordered alloys.
Research Article
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Thermal Stability and Thermoplastic Formability of Pd20Pt20Cu20Ni20P20 High Entropy Metallic Glass
Cardinal Sandrine, Pelletier Jean-Marc, Kato Hidemi
Institut National des Sciences Appliquées de Lyon, Université de Lyon, Lyon F-69621, France
Institute for Metal Materials Research, Tohoku University, Sendai 980-8577, Japan
Abstract：Thermal stability and thermo-mechanical properties of Pd20Pt20Cu20Ni20P20 high entropy metallic glass (HEMG) were investigated by differential scanning calorimetry, X-ray diffraction, and thermomechanical analysis. Results show that compared with other classical precious metal-based metallic glasses, Pd20Pt20Cu20Ni20P20 HEMG presents comparable performance with distinct characteristics.
Pu Yongliang, Qian Yiqi, Liu Yuxin, Liu Cong, Ding Jing, Zhu Shengli
School of Materials Science and Engineering, Lanzhou Jiaotong University, Lanzhou 730070, China
School of Materials Science and Engineering, Hebei University of Technology, Tianjin 300130, China
School of Energy and Machinery, Dezhou University, Dezhou 253023, China
School of Materials Science and Engineering, Tianjin University, Tianjin 300350, China
Tianjin Key Laboratory of Composite and Functional Materials, Tianjin 300350, China
Abstract：In order to improve the thermal stability and to obtain a large supercooled liquid region of metal glasses, the Zr65-x(Al0.21Ni0.29Cu0.04Ag0.46)35 x (x=0, 7.5, 15.0, 22.5) metallic glasses were investigated. The effects of component concentrations on the thermal stability, heat-induced precipitate phases, and mechanical properties were analyzed. Results show that with increasing the component concentrations, the peak position of the broad diffraction pattern shifts towards higher angles, indicating the occurrence of glass transition phenomenon. With increasing the glass transition temperature (Tg) and crystallization temperature (Tx), the liquidus temperature (Tl) is decreased, leading to decrease in the temperature difference (namely supercooled liquid region, ΔTx) between Tx and Tg and resulting in the increase in reduced glass transition range (Trg). Additionally, the nucleation activation energy (Ex) and the growth activation energy (Ep1) are increased with increasing the solute concentration. The primary crystal changes from the combination of tetragonal Zr2Ni, Zr2(Cu, Ag), ZrAg, and hexagonal Zr5Al3 phases into the single tetragonal ZrAg phase. The Vickers hardness is also increased with increasing the solute concentration. In this research, a novel metallic glass, Zr65-x(Al0.21Ni0.29-Cu0.04Ag0.46)35 x (x=7.5), is developed, which presents a large ΔTx of 141 K, high thermal stability, and strong crystallization resistance. This research adopting the multicomponent replacement strategy is of great significance to improve the thermal stability of metallic glasses.
Peng Zhen, Guo Qingyu, Sun Jian, Li Keran, Luan Hengwei, Gong Pan
School of Materials Science and Engineering, Jiangsu University, Zhenjiang 212013, China
School of Materials Science and Engineering, Huazhong University of Science and Technology, Wuhan 430074, China
Department of Mechanical Engineering, City University of Hong Kong, Hong Kong 999077, China
Hong Kong Branch of National Precious Metals Material Engineering Research Centre, City University of Hong Kong, Hong Kong 999077, China
School of Materials Science and Engineering, Tsinghua University, Beijing 100084, China
Research Institute of Huazhong University of Science and Technology, Shenzhen 518057, China
Abstract：Tribological properties of Al19Fe20-xCo20-xNi41Mo2x (x=0, 1, 2, 3, 4, 5) eutectic high-entropy alloys (EHEAs) were investigated in this research. Results show that EHEAs with trace Mo addition can form the face-centered cubic (fcc) B2 eutectic microstructure, whereas EHEAs with relatively higher Mo content can form fcc B2 μ dendritic microstructure. Mo element is beneficial to the strength enhancement of L12 phase and the ductility improvement of B2 phase. However, with increasing the Mo content to x>2, the resultant Mo-rich μ phase degrades the strength and plasticity of EHEAs. Al19Fe18Co18Ni41Mo4 EHEA has the optimal combination of high strength and high ductility. Increasing Mo content can improve the oxidation resistance of EHEAs. With increasing the Mo content, EHEA forms a tribo-oxide layer with improved oxidation resistance during sliding process, and the friction coefficient is monotonically decreased. This research provides guidance for the investigation of tribological properties of Al19Fe20-xCo20-xNi41Mo2x EHEAs.
Xiao Haiyang, Lyu Guojian, Qiao Jichao
School of Mechanics, Civil Engineering and Architecture, Northwestern Polytechnical University, Xi'an 710072, China
Abstract：To understand the dynamic mechanical properties and thermodynamic stability of β-Ti phase-embedded Zr/Ti-based bulk metallic glass composites (BMGCs), (Ti0.474Zr0.34Cu0.06Be0.126)100-xFex (x=0, 2) BMGCs were prepared and investigated. Results show that by introducing Fe element, the stability of β-Ti phase is improved. An abnormal internal friction peak can be observed due to the precipitation of ω-Ti in the metastable β-Ti phase. Below the glass transition temperature Tg, both BMGCs show abnormal overshoot on storage modulus due to the coupling effect of phase transition and partial crystallization of amorphous matrix. This research provides information about the complex dynamic mechanical relaxation behavior of the in-situ metastable β-Ti BMGCs.
Triangle Criterion of Glass-Forming Ability and Stability for Metallic Glasses
Li Xiaocheng, Kou Shengzhong, Zhao Yanchun, Li Chunyan, Li Chunling
School of Materials Science and Engineering, Lanzhou University of Technology, Lanzhou 730050, China
State Key Laboratory of Advanced Processing and Recycling of Nonferrous Metals, Lanzhou University of Technology, Lanzhou 730050, China
School of Mechanical and Electrical Engineering, Lanzhou University of Technology, Lanzhou 730050, China
Abstract：Based on the glass-forming ability (GFA) during cooling process and the glass stability (GS) of heating process, a triangle to evaluate GFA and GS, namely Tri-FAS, with the combination of pseudo-four characteristic parameters as vertices was established. Accordingly, a GFA&GA criterion (G-FAS) was deduced as G-FAS=Tg/Tl Tx/Tl Tx/Tg (Tx is onset crystallization temperature; Tl is liquid temperature; Tg is glass transition temperature). Additionally, the criterion was modified based on the competitive relationship between amorphous phase and crystal phase during cooling process and the contribution of each component to the criterion: G-FASm=Tg/(1.5Tx) Tx/Tl Tx/Tg and G-FASm′=Tg/Tl Tx/Tl (Tx/Tg )a (a≈1.5±0.2). The correlation between G-FAS and critical cooling rate Rc and that between G-FAS and Txg (Txg reflects the supercooled liquid region of glass, Txg=Tx/Tg) were discussed, which could reflect GFA and GS, respectively. Through the determination results of GFA and GS of abundant metallic glasses and other glass formers, the validity of the proposed G-FAS criterion was evaluated. Results show that with respect to both GFA and GS, the G-FAS criterion is reliable in various glass former systems, showing wide applications. The proposed Tri-FAS and G-FAS criterion can provide guidance during the fabrication and application of metallic glasses.
Comparison of Different Instability Criteria for Processing Maps of NiCoFeCrAl High Entropy Alloy
Zhang Yunsheng, Jiang Xueyu, Zhou Ge, Zhang Haoyu, Zhang Siqian, Che Xin, Chen Lijia, Cao Xue
School of Materials Science and Engineering, Shenyang University of Technology, Shenyang 110870, China
Shenyang Key Laboratory of Advanced Structural Materials and Applications, Shenyang University of Technology, Shenyang 110870, China
AECC Beijing Institute of Aeronautical Materials, Beijing 100095, China
Review Article
Creep and Recovery Behavior of Metallic Glasses: A Short Review
Nabahat Mehran, Duan Yajuan, Xu Zongrui, Qiao Jichao, Pineda Eloi
Department of Physics, Institute of Energy Technologies, Universitat Politècnica de Catalunya-BarcelonaTech, Barcelona 08019, Spain
School of Mechanics, Civil Engineering and Architecture, Northwestern Polytechnical University, Xi'an 710072, China
Abstract：Due to the disordered structure of amorphous alloys, the complex structural dynamics involves the particle rearrangements with a large span in time and size scales. The characterization and mechanism of structural dynamics of amorphous alloys are crucial and fundamental for the further research of relaxation behavior and physical aging kinetics of glasses. Abundant researches show that the relaxation spectra of rare-earth-based amorphous alloys, which are represented by lanthanum- and cerium-based alloys, show obvious secondary relaxation process, and the system becomes an ideal carrier to investigate the relationship between structural dynamics and mechanical properties of amorphous alloys. In this review, the anelasticity of metallic glasses was discussed. The anelastic deformation, as the main component of deformation, can totally recovery after unloading in creep experiments, and its mechanism is important to form deep understanding about the structural dynamics of metallic glasses. Additionally, the main characteristics of anelastic deformation during creep and creep recovery were summarized, and some theoretical models for quantitative and qualitative description were introduced.
Research Progress of Al-Ti-V-based Lightweight High-Entropy Alloys
Xue Yuan, Shan Guibin, Pan Ruilin, Tang Song, Lan Si
School of Materials Science and Engineering, Nanjing University of Science and Technology, Nanjing 210094, China
Abstract：In recent years, high-entropy alloys (HEAs) have become the research hotspot in the field of metal structural materials because of their novel design concepts and excellent physicochemical properties. With the continuous popularization of lightweight alloy design concepts, the conception of “entropy regulation” has been widely used to develop new lightweight alloys. Lightweight HEAs (LHEAs) are a new type of low density HEAs based on lightweight alloy designs. Their development and design mainly combine the empirical parameter criteria, phase diagram calculations, and first-principles calculations. Al-Ti-V-based LHEAs attract much attention among various LHEAs due to their excellent mechanical properties, good high temperature oxidation resistance, and fine corrosion resistance. This paper summarized the research progress of Al-Ti-V-based LHEAs from the perspective of composition design, preparation methods, microstructures, and physicochemical properties. Meanwhile, the problems and challenges for Al-Ti-V-based LHEAs were also prospected.
Relaxation Behavior in Metallic Glasses and Related Mechanisms by Simulation Method: A Brief Review
Wang Bing, Gao Xuanqiao, Qiao Jichao
School of Physical Science and Technology, Northwestern Polytechnical University, Xi'an 710072, China
Innovation Center NPU Chong-qing, Northwestern Polytechnical University, Chongqing 401135, China
Northwest Institute for Nonferrous Metal Research, Xi'an 710016, China；
School of Mechanics, Civil Engineering and Architecture, Northwestern Polytechnical University, Xi'an 710072, China
Abstract：The relaxation dynamics of metallic glasses, as one of the most challenging issues, is complex. The relaxation, including α relaxation, slow β relaxation, and fast β relaxation, occurs at different temperatures. Taking advantage of the microscopic atomic information of simulation, the characteristics and mechanisms of these three typical relaxations were summarized to discuss their influence on mechanical properties of metallic glasses. Recent progresses on dynamical, structural, and physical mechanisms by simulation method were discussed. This review is beneficial to understand the nature of glass and to establish the dynamics-structure-property relationship of glassy materials.
Wang Liyuan, Jiang Jiali, Wang Dengke, Zhang Yi, Wang Qing, Lu Jian
Institute of Materials, Shanghai University, Shanghai 200444, China
Department of Mechanical Engineering, City University of Hong Kong, Hong Kong 999077, China
Abstract：The control of atomic-scale structure of metallic glasses (MGs) to improve their physical, chemical, and mechanical properties is an essential issue. Over past decades, large efforts have been devoted into the development of effective MG control approaches, such as the cryogenic treatment (CT) technique. This research reviewed the effects of cryogenic treatment on the properties and their dependence on the initial structural energy state of MGs. Then, it focused on the atomic-scale structure evolution in MGs during CT, which is of fundamental importance to understand CT effects.
