Volume 40,Issue 10,2011 Table of Contents
2011, 40(10):1693-1698.
Abstract:
In order to improve the hydriding and dehydriding kinetics of the Mg2Ni-type alloy, Ni in the alloy was partially substituted by element Cu. The nanocrystalline Mg2Ni1-xCux (x=0, 0.1, 0.2, 0.3, 0.4) alloys were prepared by melt-spinning technology. The structures of the as-cast and spun alloys were analyzed by XRD, SEM and HRTEM. The hydriding and dehydriding kinetics of the alloys were measured by using an automatically controlled Sieverts apparatus. The results show that all the as-spun alloys hold a nanocrystalline structure. The substitution of Cu for Ni leads to form secondary phase Mg2Cu without changing of the major phase of Mg2Ni in the alloy, The hydrogen absorption capacity of the alloys first increases and then decreases with rising of Cu content, but the hydrogen desorption capacity of the alloys monotonously grows with increasing of Cu content. The melt spinning significantly improves the hydrogenation and dehydrogenation capacity and the kinetics of the alloys.
In order to improve the hydriding and dehydriding kinetics of the Mg2Ni-type alloy, Ni in the alloy was partially substituted by element Cu. The nanocrystalline Mg2Ni1-xCux (x=0, 0.1, 0.2, 0.3, 0.4) alloys were prepared by melt-spinning technology. The structures of the as-cast and spun alloys were analyzed by XRD, SEM and HRTEM. The hydriding and dehydriding kinetics of the alloys were measured by using an automatically controlled Sieverts apparatus. The results show that all the as-spun alloys hold a nanocrystalline structure. The substitution of Cu for Ni leads to form secondary phase Mg2Cu without changing of the major phase of Mg2Ni in the alloy, The hydrogen absorption capacity of the alloys first increases and then decreases with rising of Cu content, but the hydrogen desorption capacity of the alloys monotonously grows with increasing of Cu content. The melt spinning significantly improves the hydrogenation and dehydrogenation capacity and the kinetics of the alloys.
2011, 40(10):1699-1702.
Abstract:
A novel CVD method of preparing ultrafine rhenium powders was investigated in this paper. The Re2O7 gas obtained by decomposing NH4ReO7 was transported to the reduction chamber and then reduced by H2 to form rhenium powders. In order to evaluate the effects of sintering on properties of rhenium particles, such as crystal size, morphology, surface conditions and particle size, the samples of rhenium powders prepared at different reduction temperatures were characterized by X-ray diffraction (XRD), scanning electron microscopy (SEM) and laser particle size analyzer. The experimental results show that the sintering effect among particles is enhanced with increasing of reduction temperature, resulting in larger crystal size, smoother surface and larger average particle size of the rhenium powder.
A novel CVD method of preparing ultrafine rhenium powders was investigated in this paper. The Re2O7 gas obtained by decomposing NH4ReO7 was transported to the reduction chamber and then reduced by H2 to form rhenium powders. In order to evaluate the effects of sintering on properties of rhenium particles, such as crystal size, morphology, surface conditions and particle size, the samples of rhenium powders prepared at different reduction temperatures were characterized by X-ray diffraction (XRD), scanning electron microscopy (SEM) and laser particle size analyzer. The experimental results show that the sintering effect among particles is enhanced with increasing of reduction temperature, resulting in larger crystal size, smoother surface and larger average particle size of the rhenium powder.
2011, 40(10):1703-1707.
Abstract:
Various nanostructured titania thin films were fabricated by direct oxidation of metallic Ti substrates in hydrogen peroxide solutions with the additives of nitric acid and block copolymers of P123 or F127. X-ray diffraction (XRD), scanning electron microscopy (SEM) and ultraviolet-visible diffuse reflectance spectra (UV-Vis DRS) were utilized to analyze the morphology and structure of the titania films. Photocatalytic properties of the thin films were evaluated by the degradation of rhodamine B in water under the illumination of a high-pressure mercury lamp. The film only with the block copolymer additive consists of rod-like titania; while flower-like titania aggregates are achieved when both block copolymers and nitric acid are added to the hydrogen peroxide solution. After a subsequent calcination at 450 oC, all the titania films are crystallized further to a mixture of anatase and rutile with a similar average grain size. An indirect bandgap of 2.65-2.85 eV is estimated for the present films, which is significantly lower that of the bulk titania. The titania film derived with the P123 additive shows higher photocatalytic activity than that with the F127 additive, either with or without the additive of nitric acid.
Various nanostructured titania thin films were fabricated by direct oxidation of metallic Ti substrates in hydrogen peroxide solutions with the additives of nitric acid and block copolymers of P123 or F127. X-ray diffraction (XRD), scanning electron microscopy (SEM) and ultraviolet-visible diffuse reflectance spectra (UV-Vis DRS) were utilized to analyze the morphology and structure of the titania films. Photocatalytic properties of the thin films were evaluated by the degradation of rhodamine B in water under the illumination of a high-pressure mercury lamp. The film only with the block copolymer additive consists of rod-like titania; while flower-like titania aggregates are achieved when both block copolymers and nitric acid are added to the hydrogen peroxide solution. After a subsequent calcination at 450 oC, all the titania films are crystallized further to a mixture of anatase and rutile with a similar average grain size. An indirect bandgap of 2.65-2.85 eV is estimated for the present films, which is significantly lower that of the bulk titania. The titania film derived with the P123 additive shows higher photocatalytic activity than that with the F127 additive, either with or without the additive of nitric acid.
2011, 40(10):1708-1712.
Abstract:
The microstructure and mechanical properties of ZK60 alloy sheet produced by different method were investigated using OM, SEM, TEM and a standard universal testing machine. The results show that, for conventional casting (CC) alloy, the equiaxed structure is refined after warm rolling. But for twin roll casting alloy, the microstructure changes from dendrite to fibrous deformed structure after warm rolling. Relatively higher density of shear bands can be observable in TRC ZK60 alloy sheet and no obvious dynamic recrystallization has been found after warm rolling. After warm rolling, the two alloys possess good mechanical properties, and the strength of TRC alloy is much higher than that of CC alloy, and elongation of TRC alloy is a little lower than that of CC alloy. The annealing heat treatment after warm rolling will induce a little decrease of strength and great increase of elongation of the two alloys. The tensile strength, yield strength and elongation of TRC and CC alloy sheet are 388 MPa, 301 MPa, 22.9%, and 311 MPa, 219 MPa, 19.3%, respectively. The grain refinement during manufacturing processes is attributed to the forma-tion of heavy shear bands, high density dislocation, twins, and the recrystallization during subsequent annealing proc-ess
The microstructure and mechanical properties of ZK60 alloy sheet produced by different method were investigated using OM, SEM, TEM and a standard universal testing machine. The results show that, for conventional casting (CC) alloy, the equiaxed structure is refined after warm rolling. But for twin roll casting alloy, the microstructure changes from dendrite to fibrous deformed structure after warm rolling. Relatively higher density of shear bands can be observable in TRC ZK60 alloy sheet and no obvious dynamic recrystallization has been found after warm rolling. After warm rolling, the two alloys possess good mechanical properties, and the strength of TRC alloy is much higher than that of CC alloy, and elongation of TRC alloy is a little lower than that of CC alloy. The annealing heat treatment after warm rolling will induce a little decrease of strength and great increase of elongation of the two alloys. The tensile strength, yield strength and elongation of TRC and CC alloy sheet are 388 MPa, 301 MPa, 22.9%, and 311 MPa, 219 MPa, 19.3%, respectively. The grain refinement during manufacturing processes is attributed to the forma-tion of heavy shear bands, high density dislocation, twins, and the recrystallization during subsequent annealing proc-ess
2011, 40(10):1713-1717.
Abstract:
Adopting a large plastic deformation process, the dispersion strengthened Pt5Rh composite was prepared. The microstructure of the composite was analyzed by SEM, and the high temperature creep tests were carried out by a self-made high temperature creep test facility. The experiment results show that at high temperature and under low load the stress exponent of the dispersion strengthened Pt5Rh alloy does not change obviously with increasing of the temperature, and its apparent activation energy is much higher than those of pure platinum and Pt10Rh alloy. The high temperature creep properties of the dispersion strengthened Pt5Rh are better than those of conventional alloys. The creep mechanism of the dispersion strengthened Pt5Rh belongs to the proliferation creep mechanism; the creep fracture at high temperatures presents the brittle fracture
Adopting a large plastic deformation process, the dispersion strengthened Pt5Rh composite was prepared. The microstructure of the composite was analyzed by SEM, and the high temperature creep tests were carried out by a self-made high temperature creep test facility. The experiment results show that at high temperature and under low load the stress exponent of the dispersion strengthened Pt5Rh alloy does not change obviously with increasing of the temperature, and its apparent activation energy is much higher than those of pure platinum and Pt10Rh alloy. The high temperature creep properties of the dispersion strengthened Pt5Rh are better than those of conventional alloys. The creep mechanism of the dispersion strengthened Pt5Rh belongs to the proliferation creep mechanism; the creep fracture at high temperatures presents the brittle fracture
2011, 40(10):1718-1720.
Abstract:
Solid bonding diffusion couples of U-Mo/Nb were made by clad and hot rolling. The diffusion couples were heat-treated at 790 °C for different time. The obversation of the diffusion layers was taken by scan electronic microscope and the main elements in different solid state phases were measured by energy dispersive spectrometer. The research results indicate that there exist were three different U-Nb phases coming into the Nb-base side of the diffusion couple heat-treated for 30 h. The phase components of the final solid state are associated with the phase transformation of U and the solubility of alloy elements in different U-phase
Solid bonding diffusion couples of U-Mo/Nb were made by clad and hot rolling. The diffusion couples were heat-treated at 790 °C for different time. The obversation of the diffusion layers was taken by scan electronic microscope and the main elements in different solid state phases were measured by energy dispersive spectrometer. The research results indicate that there exist were three different U-Nb phases coming into the Nb-base side of the diffusion couple heat-treated for 30 h. The phase components of the final solid state are associated with the phase transformation of U and the solubility of alloy elements in different U-phase
2011, 40(10):1721-1726.
Abstract:
The quenching process of TC21 titanium alloy forging was simulated by ANSYS finite element analysis software, and the temperature field and the thermal stress field of TC21 titanium alloy forging at different quenching time were obtained, as well as the relationship between the temperature and stress of selected nodes and quenching time. Moreover, the change of microstructure from the forging center to the edge was observed in order to study the effect of cooling rate on the microstructure change. The results show that when the quenching time reaches to 3600 s, the forging surface has cooled to room temperature, while the forging center still maintains a high temperature; the cooling rate increases continually from the forging center to the surface, and the microstructure becomes much finer with the distance from the surface decreasing. At the beginning of quenching, the thermal stress of all parts of the forging rises to the peak rapidly, and then the thermal stress of the surface and the center decrease gradually with the quenching time increasing. The maximum residual stress is only 77 MPa at the end of quenching.
The quenching process of TC21 titanium alloy forging was simulated by ANSYS finite element analysis software, and the temperature field and the thermal stress field of TC21 titanium alloy forging at different quenching time were obtained, as well as the relationship between the temperature and stress of selected nodes and quenching time. Moreover, the change of microstructure from the forging center to the edge was observed in order to study the effect of cooling rate on the microstructure change. The results show that when the quenching time reaches to 3600 s, the forging surface has cooled to room temperature, while the forging center still maintains a high temperature; the cooling rate increases continually from the forging center to the surface, and the microstructure becomes much finer with the distance from the surface decreasing. At the beginning of quenching, the thermal stress of all parts of the forging rises to the peak rapidly, and then the thermal stress of the surface and the center decrease gradually with the quenching time increasing. The maximum residual stress is only 77 MPa at the end of quenching.
2011, 40(10):1727-1731.
Abstract:
Dislocation cells, geometrically necessary boundaries (GNB) and twins in drawn single crystal copper wires produced by Ohno continuous casting (OCC) method have been analyzed by TEM. The results show that when the strains are lower than 0.94, the microstructures of drawn single crystal can be characterized as dislocation cells. When the strains are more than 0.94, there are two kinds of microstructures. One is that dislocation cells are elongated in longitudinal section and equiaxed in cross section. The size of dislocation cells decreases as the strain increases until they reach a critical size of about 0.28 μm at a strain of 1.39. The other is geometrically necessary boundaries. At low strains, two kinds of geometrically necessary boundaries are along {111}, and at high strains, geometrically necessary boundaries are parallel to drawn direction. In addition, it is found that in dawn single crystal copper wires, there are two types of twins in the single crystal copper wires. One is formed in the preparing process of single crystal copper wires by Ohno continuous casting method, and the other is formed during cold drawing deformation.
Dislocation cells, geometrically necessary boundaries (GNB) and twins in drawn single crystal copper wires produced by Ohno continuous casting (OCC) method have been analyzed by TEM. The results show that when the strains are lower than 0.94, the microstructures of drawn single crystal can be characterized as dislocation cells. When the strains are more than 0.94, there are two kinds of microstructures. One is that dislocation cells are elongated in longitudinal section and equiaxed in cross section. The size of dislocation cells decreases as the strain increases until they reach a critical size of about 0.28 μm at a strain of 1.39. The other is geometrically necessary boundaries. At low strains, two kinds of geometrically necessary boundaries are along {111}, and at high strains, geometrically necessary boundaries are parallel to drawn direction. In addition, it is found that in dawn single crystal copper wires, there are two types of twins in the single crystal copper wires. One is formed in the preparing process of single crystal copper wires by Ohno continuous casting method, and the other is formed during cold drawing deformation.
2011, 40(10):1731-1736.
Abstract:
Fe16Al2Cr porous material was prepared by compression molding, vacuum sintering using Fe16Al2Cr pre-alloy powder as raw material. The relationship between powder pressing pressure and Fe16Al2Cr porous material performance was researched. The results show that Fe16Al2Cr powder less than 31 μm of particles size is poor compaction performance and green body strength. In process of the power sintering, the axial contraction is bigger than radial contraction, and decreased with the pressing pressure increased. Pressing pressure and sintering time is almost no effects the radial shrinkage at higher sintering temperature. The porosity, pore size and permeability of Fe16Al2Cr porous material decrease with pressing pressure increases, and increases with the sintering time prolongation. Increasing pressing pressure and sintering time help to improve the shear strength of Fe16Al2Cr porous materials.
Fe16Al2Cr porous material was prepared by compression molding, vacuum sintering using Fe16Al2Cr pre-alloy powder as raw material. The relationship between powder pressing pressure and Fe16Al2Cr porous material performance was researched. The results show that Fe16Al2Cr powder less than 31 μm of particles size is poor compaction performance and green body strength. In process of the power sintering, the axial contraction is bigger than radial contraction, and decreased with the pressing pressure increased. Pressing pressure and sintering time is almost no effects the radial shrinkage at higher sintering temperature. The porosity, pore size and permeability of Fe16Al2Cr porous material decrease with pressing pressure increases, and increases with the sintering time prolongation. Increasing pressing pressure and sintering time help to improve the shear strength of Fe16Al2Cr porous materials.
2011, 40(10):1737-1741.
Abstract:
The precipitation behavior of the secondary M23C6 carbide in Ni-Cr-W based superalloy was studied by DSC, SEM and TEM systematically. The results show that secondary M23C6 carbide precipitates from 648 to 1147 °C and it dissolves into the matrix when the temperature is above 1160 °C. The primary M6C carbide decomposes at 1349 °C and the alloy melts completely at 1400 °C. There are two morphologies of M23C6 precipitate at the grain boundaries. Coarse lamella M23C6 precipitates from 655 to 900 °C and it changes to discrete particles above 900 °C. The cooling rate has an important effect on M23C6 precipitation behavior. In addition, during the cooling process, the serrated grain boundaries are formed because of the discrete M23C6 carbide particles which precipitate at grain boundaries.
The precipitation behavior of the secondary M23C6 carbide in Ni-Cr-W based superalloy was studied by DSC, SEM and TEM systematically. The results show that secondary M23C6 carbide precipitates from 648 to 1147 °C and it dissolves into the matrix when the temperature is above 1160 °C. The primary M6C carbide decomposes at 1349 °C and the alloy melts completely at 1400 °C. There are two morphologies of M23C6 precipitate at the grain boundaries. Coarse lamella M23C6 precipitates from 655 to 900 °C and it changes to discrete particles above 900 °C. The cooling rate has an important effect on M23C6 precipitation behavior. In addition, during the cooling process, the serrated grain boundaries are formed because of the discrete M23C6 carbide particles which precipitate at grain boundaries.
2011, 40(10):1742-1747.
Abstract:
The high-temperature oxidation resistance of Co-Al-W alloy, strengthened by a ternary compound γ′-Co3(Al, W) phase, was investigated. The kinetic data of mass gain and the cyclic oxidation behavior of the Co-Al-W alloys, including Co-9Al-7.5W (7.5W), Co-9Al-9.8W (9.8W) and Co-9.2Al-10.7W (10.7W), were studied at 800 and 900 oC by XRD, SEM and EPMA technologies, and they were compared with a nickel-base Manaurite900 (MAN900) alloy. The results show that the anti-oxidative ability of 9.8W alloy is the best at 800 oC among these alloys. But at 900 oC the square of mass gain of 7.5W and 9.8W alloys are much greater, while the anti-oxidant property of MAN900 and 10.7W alloys are superior to other alloys. The oxide scales at 800 and 900 oC exhibit a multi-layered structure, including an outer layer of Co3O4, an intermediate layer composed of complex oxides of Co, Al and W elements layer, and an internal attacked layer with oxides of Co and Al.
The high-temperature oxidation resistance of Co-Al-W alloy, strengthened by a ternary compound γ′-Co3(Al, W) phase, was investigated. The kinetic data of mass gain and the cyclic oxidation behavior of the Co-Al-W alloys, including Co-9Al-7.5W (7.5W), Co-9Al-9.8W (9.8W) and Co-9.2Al-10.7W (10.7W), were studied at 800 and 900 oC by XRD, SEM and EPMA technologies, and they were compared with a nickel-base Manaurite900 (MAN900) alloy. The results show that the anti-oxidative ability of 9.8W alloy is the best at 800 oC among these alloys. But at 900 oC the square of mass gain of 7.5W and 9.8W alloys are much greater, while the anti-oxidant property of MAN900 and 10.7W alloys are superior to other alloys. The oxide scales at 800 and 900 oC exhibit a multi-layered structure, including an outer layer of Co3O4, an intermediate layer composed of complex oxides of Co, Al and W elements layer, and an internal attacked layer with oxides of Co and Al.
2011, 40(10):1748-1751.
Abstract:
The finite element model (FEM) for tungsten alloy penetrating Q235 steel plate with a high speed has been built up by adopting LS-DYNA software, and the velocity and the evolution process of deformation, damage and failure for tungsten alloy projectiles during the penetrating process has been acquired. The effects of the properties of tungsten alloy on the penetrating process have been studied systematically. The result shows that the density, yield strength and fail strain have important effects on the velocity and failure, but the hardening parameter and the strain rate factor only have a minor effect. This study is helpful to the understanding of penetrating process of tungsten alloy, and a theory reference is also provided for making tungsten alloys with better penetrating properties.
The finite element model (FEM) for tungsten alloy penetrating Q235 steel plate with a high speed has been built up by adopting LS-DYNA software, and the velocity and the evolution process of deformation, damage and failure for tungsten alloy projectiles during the penetrating process has been acquired. The effects of the properties of tungsten alloy on the penetrating process have been studied systematically. The result shows that the density, yield strength and fail strain have important effects on the velocity and failure, but the hardening parameter and the strain rate factor only have a minor effect. This study is helpful to the understanding of penetrating process of tungsten alloy, and a theory reference is also provided for making tungsten alloys with better penetrating properties.
2011, 40(10):1752-1756.
Abstract:
An experimental and theoretical study of single-crystal silicon joining was undertaken by the comparison of two joining methods of eutectic joining and pre-eutectic joining. The results indicate that when holding for 30 min, the lowest joining temperatures for eutectic and pre-eutectic joining are 600 oC and 430 oC, respectively. Thermodynamic analysis shows that during the eutectic joining, the main resistance to the eutectic liquid formation is the transformation from Au and Si to Au or Si base supersaturated solid solutions (SSS). However, cladding of Au-Si eutectic layer is prefabricated in the surface to be joined by pre-eutectic joining. Since separation between Au and Si is insufficient during the cladding cooling, the supersaturate solid solution (SSS) exists inside the cladding and around the cladding/substrate interface. As a result, the re-eutectic of Au-Si during the pre-eutectic joining process is not impeded by the above-mentioned resistance, but promoted by the Gibbs free energy decrease induced by the transformation from the SSS to eutectic liquid. Therefore, the re-eutectic liquid is more prone to appear, and the joining temperature is observably reduced.
An experimental and theoretical study of single-crystal silicon joining was undertaken by the comparison of two joining methods of eutectic joining and pre-eutectic joining. The results indicate that when holding for 30 min, the lowest joining temperatures for eutectic and pre-eutectic joining are 600 oC and 430 oC, respectively. Thermodynamic analysis shows that during the eutectic joining, the main resistance to the eutectic liquid formation is the transformation from Au and Si to Au or Si base supersaturated solid solutions (SSS). However, cladding of Au-Si eutectic layer is prefabricated in the surface to be joined by pre-eutectic joining. Since separation between Au and Si is insufficient during the cladding cooling, the supersaturate solid solution (SSS) exists inside the cladding and around the cladding/substrate interface. As a result, the re-eutectic of Au-Si during the pre-eutectic joining process is not impeded by the above-mentioned resistance, but promoted by the Gibbs free energy decrease induced by the transformation from the SSS to eutectic liquid. Therefore, the re-eutectic liquid is more prone to appear, and the joining temperature is observably reduced.
2011, 40(10):1757-1761.
Abstract:
Electroless deposited Pd coats have been prepared on Nb-Ni-Ti alloy membranes and glass substrates, XRD, DSC, SEM and EDX analysis were employed to determine the phase compositions, thermal stabilities and surface morphology of Pd deposited coats in this paper. It revealed that prepared Pd coat appeared to be a particle-deposited surface image with amorphous microstructure, consisting of numerous spherical particles (1 μm or so) arranged in single-layer form, the content of P in the coats is about 3 wt%-4 wt%. Such coat can keep its original appearance, but slight increase of particle size, strong intensity of Pd phase and Pd6P have been observed after heat treatment at 675 K. Hydrogen diffusion coefficient of Nb-Ni-Ti alloy membranes with original amorphous Pd coat is quite higher than that of samples without Pd coat, as well as that of samples with Pd coat after heat treatment at 675 K, indicating that prepared Pd coat has good catalytic effect on hydrogen permeation of Nb-Ni-Ti alloy membranes.
Electroless deposited Pd coats have been prepared on Nb-Ni-Ti alloy membranes and glass substrates, XRD, DSC, SEM and EDX analysis were employed to determine the phase compositions, thermal stabilities and surface morphology of Pd deposited coats in this paper. It revealed that prepared Pd coat appeared to be a particle-deposited surface image with amorphous microstructure, consisting of numerous spherical particles (1 μm or so) arranged in single-layer form, the content of P in the coats is about 3 wt%-4 wt%. Such coat can keep its original appearance, but slight increase of particle size, strong intensity of Pd phase and Pd6P have been observed after heat treatment at 675 K. Hydrogen diffusion coefficient of Nb-Ni-Ti alloy membranes with original amorphous Pd coat is quite higher than that of samples without Pd coat, as well as that of samples with Pd coat after heat treatment at 675 K, indicating that prepared Pd coat has good catalytic effect on hydrogen permeation of Nb-Ni-Ti alloy membranes.
2011, 40(10):1762-1766.
Abstract:
The mechanism of mechanically activated hydrogenation-disproportionation reaction of Nd16Fe76B8 alloy was investigated. The aspects of the kinetics for the mechanically activated hydrogenation-disproportionation were studied by measuring the hydrogen absorption of the alloy during milling, and the phase and microstructure change was characterized by X-ray diffraction (XRD), transmission electron microscopy (TEM), and scanning electron microscopy (SEM), respectively. The results show that, firstly, the Nd-rich phase and Nd2Fe14B matrix phase in the Nd16Fe76B8 alloy is hydrogenated into NdH2.7 and Nd2Fe14BHy. After that, the alloy powder is activated by further milling in hydrogen, and then disproportionated into α-Fe, NdH2.7 and Fe2B phases, with a grain size of about 10 nm.
The mechanism of mechanically activated hydrogenation-disproportionation reaction of Nd16Fe76B8 alloy was investigated. The aspects of the kinetics for the mechanically activated hydrogenation-disproportionation were studied by measuring the hydrogen absorption of the alloy during milling, and the phase and microstructure change was characterized by X-ray diffraction (XRD), transmission electron microscopy (TEM), and scanning electron microscopy (SEM), respectively. The results show that, firstly, the Nd-rich phase and Nd2Fe14B matrix phase in the Nd16Fe76B8 alloy is hydrogenated into NdH2.7 and Nd2Fe14BHy. After that, the alloy powder is activated by further milling in hydrogen, and then disproportionated into α-Fe, NdH2.7 and Fe2B phases, with a grain size of about 10 nm.
2011, 40(10):1767-1770.
Abstract:
The thermal stability of Zr50Ti5Cu18Ni17Al10 bulk metallic glass was studied by differential scanning calorimeter (DSC) in the mode of continuous heating. The activation energies of glass transition (Eg) and crystallization (Ep1 and Ep2) are 438±11, 284±8 and 323±11 kJ/mol, respectively. The study of mechanical properties was conducted in compression at room temperature under an initial strain rate of 1×10?4 s?1. The metallic glass rods with a diameter of 3 mm exhibit a good mechanical property. The plastic strain prior to fracture is up to 3%, and the maximum values of Young’s modulus and ultimate fracture strength are 90 GPa and 1968 MPa, respectively. The intersecting, branching and sliding of multiple shear bands and the larger critical shear offset with a width of 60 mm are the major reason for the higher compressive plasticity in the Zr50Ti5Cu18Ni17Al10 bulk metallic glass.
The thermal stability of Zr50Ti5Cu18Ni17Al10 bulk metallic glass was studied by differential scanning calorimeter (DSC) in the mode of continuous heating. The activation energies of glass transition (Eg) and crystallization (Ep1 and Ep2) are 438±11, 284±8 and 323±11 kJ/mol, respectively. The study of mechanical properties was conducted in compression at room temperature under an initial strain rate of 1×10?4 s?1. The metallic glass rods with a diameter of 3 mm exhibit a good mechanical property. The plastic strain prior to fracture is up to 3%, and the maximum values of Young’s modulus and ultimate fracture strength are 90 GPa and 1968 MPa, respectively. The intersecting, branching and sliding of multiple shear bands and the larger critical shear offset with a width of 60 mm are the major reason for the higher compressive plasticity in the Zr50Ti5Cu18Ni17Al10 bulk metallic glass.
2011, 40(10):1771-1774.
Abstract:
The texture evolution of Ni5W out layer in the composite tapes with multi-layer structure was investigated by the means of four circle X-ray diffraction and EBSD techniques. Results show that both the gradient distribution of deformation texture and the diffusion between each layer dominate the texture development of the Ni5W out layer in the composite tapes. This explanation is useful in view of discussing the relationships governing the texture formation of each layer in composite tapes.
The texture evolution of Ni5W out layer in the composite tapes with multi-layer structure was investigated by the means of four circle X-ray diffraction and EBSD techniques. Results show that both the gradient distribution of deformation texture and the diffusion between each layer dominate the texture development of the Ni5W out layer in the composite tapes. This explanation is useful in view of discussing the relationships governing the texture formation of each layer in composite tapes.
2011, 40(10):1775-1779.
Abstract:
The microstructure and mechanical properties of 5A90 Al-Li alloy sheet joint by laser welding with filler wire (LWFW) have been studied. The results indicate that the major microstructure characteristics of the joint by LWFW are fine-grained layer and equiaxed grains in most of the welded seam, which are also the major characteristics of the joint by laser beam welding (LBW). However, compared with the joint by LBW, the microstructure of the joint by LWFW is finer, and the range of the columnar crystals zone is prone to decrease. The microhardness HV0.2 of welded seam by LWFW (925.7 MPa) is lower than that by LBW (956.5 MPa), but the uniformity of the former is better than that of the latter. The ultimate strength of the joint by LWFW is lower than that by LBW slightly, which reach to 73.03 % and 79.22% of the base metal, respectively, whereas the elongations after fracture of the former joint is higher than that of the latter joint significantly, which reach to 38.65 % and 20.38 % of the base metal, respectively. Form those results, the microstructure and mechanical properties of 5A90 Al-Li alloy by LWFW are better than that by LBW slightly. If the combined mechanical properties of the joint by LWFW meet the operation requirements, it should be improved by heat treatment after welding, and it also should develop a better filler wire matched with the base metal.
The microstructure and mechanical properties of 5A90 Al-Li alloy sheet joint by laser welding with filler wire (LWFW) have been studied. The results indicate that the major microstructure characteristics of the joint by LWFW are fine-grained layer and equiaxed grains in most of the welded seam, which are also the major characteristics of the joint by laser beam welding (LBW). However, compared with the joint by LBW, the microstructure of the joint by LWFW is finer, and the range of the columnar crystals zone is prone to decrease. The microhardness HV0.2 of welded seam by LWFW (925.7 MPa) is lower than that by LBW (956.5 MPa), but the uniformity of the former is better than that of the latter. The ultimate strength of the joint by LWFW is lower than that by LBW slightly, which reach to 73.03 % and 79.22% of the base metal, respectively, whereas the elongations after fracture of the former joint is higher than that of the latter joint significantly, which reach to 38.65 % and 20.38 % of the base metal, respectively. Form those results, the microstructure and mechanical properties of 5A90 Al-Li alloy by LWFW are better than that by LBW slightly. If the combined mechanical properties of the joint by LWFW meet the operation requirements, it should be improved by heat treatment after welding, and it also should develop a better filler wire matched with the base metal.
2011, 40(10):1780-1784.
Abstract:
The effect of different ultrasonic power, duration and holding time on AZ80 magnesium alloy melt purification by ultrasonic field was studied. The results indicate that the ultrasonic treatment can accelerate separation of inclusions in the melt and attain melt purification. When the ultrasonic power is 80 W at 650 oC, ultrasonic duration 60 s, and holding time 100 s, the melt has the best purification effect. The more inclusions the ingot has, the lower conductivity is, so the conductivity can characterize the level of purification.
The effect of different ultrasonic power, duration and holding time on AZ80 magnesium alloy melt purification by ultrasonic field was studied. The results indicate that the ultrasonic treatment can accelerate separation of inclusions in the melt and attain melt purification. When the ultrasonic power is 80 W at 650 oC, ultrasonic duration 60 s, and holding time 100 s, the melt has the best purification effect. The more inclusions the ingot has, the lower conductivity is, so the conductivity can characterize the level of purification.
2011, 40(10):1785-1789.
Abstract:
The master Zr(V1-xFex)2 (x=0.15) alloy was prepared by the arc-melt method. The alloy was re-melted and melt-spun by single-roller melt spinning at the various copper wheel velocity. From phase analysis and microstructure investigation, it has been shown melt-spun technique could prevent the residual phases of peritectic reaction during solidification and eliminate the dendritic segregation in the as-cast state. The ribbons spun at various velocities could absorb about 2% H/M hydrogen without changing their structure. For the alloy spun at each speed, the cell volume expansion with the saturated hydrogen absorption is about 20% and the he equilibrium pressure is less than 10-5 Pa at room temperature extrapolated by Van’t Hoff equation.
The master Zr(V1-xFex)2 (x=0.15) alloy was prepared by the arc-melt method. The alloy was re-melted and melt-spun by single-roller melt spinning at the various copper wheel velocity. From phase analysis and microstructure investigation, it has been shown melt-spun technique could prevent the residual phases of peritectic reaction during solidification and eliminate the dendritic segregation in the as-cast state. The ribbons spun at various velocities could absorb about 2% H/M hydrogen without changing their structure. For the alloy spun at each speed, the cell volume expansion with the saturated hydrogen absorption is about 20% and the he equilibrium pressure is less than 10-5 Pa at room temperature extrapolated by Van’t Hoff equation.
2011, 40(10):1790-1794.
Abstract:
IrO2 thin films were prepared on Si (100) substrates by pulsed laser deposition (PLD) technique. Emphases were given on the variation of the electrical resistivity and microstructure of IrO2 thin films before and after being annealed at air atmosphere. The composition and microstructure of IrO2 thin films were characterized by using x-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS), atomic force microscopy (AFM), and the four-point probe method was used to measure their electrical resistivity. Hall measurements were used to study the electrical mechanism of IrO2 films. The results show that the annealing in air could improve the conductivity of IrO2 films, and the minimum electrical resistivity of 37 μΩ·cm is obtained at 750 °C. IrO2 films had a significant positive temperature dependence of resistivity at 25-500 °C, showing a typical metallic conduction behavior. It is found that IrO2 films deposited at the substrate temperature of 250-400 °C exhibited p-type conduction, while the conductivity type changed to n-type when the temperature increased to above 500 °C.
IrO2 thin films were prepared on Si (100) substrates by pulsed laser deposition (PLD) technique. Emphases were given on the variation of the electrical resistivity and microstructure of IrO2 thin films before and after being annealed at air atmosphere. The composition and microstructure of IrO2 thin films were characterized by using x-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS), atomic force microscopy (AFM), and the four-point probe method was used to measure their electrical resistivity. Hall measurements were used to study the electrical mechanism of IrO2 films. The results show that the annealing in air could improve the conductivity of IrO2 films, and the minimum electrical resistivity of 37 μΩ·cm is obtained at 750 °C. IrO2 films had a significant positive temperature dependence of resistivity at 25-500 °C, showing a typical metallic conduction behavior. It is found that IrO2 films deposited at the substrate temperature of 250-400 °C exhibited p-type conduction, while the conductivity type changed to n-type when the temperature increased to above 500 °C.
2011, 40(10):1795-1798.
Abstract:
By means of the technology of split Hopkinson bar, dynamic compression experimentation on TC6 titanium alloy have been carried out for cylindrical specimens cut along different directions of deformed contexture. The susceptibility of the different directions of deformed contexture of the TC6 titanium alloy to adiabatic shearing has been studied by means of associating their mechanical response under high strain rate with micro-analysis. Results show that the sensitivities of the different directions to adiabatic shearing are highly anisotropy. RD has the lowest sensitivity to adiabatic shearing and ND has the highest to adiabatic shearing. The differences of susceptibility of the different directions of deformed contexture to adiabatic shearing are caused by different thermal softening effect in the course of dynamic deformation
By means of the technology of split Hopkinson bar, dynamic compression experimentation on TC6 titanium alloy have been carried out for cylindrical specimens cut along different directions of deformed contexture. The susceptibility of the different directions of deformed contexture of the TC6 titanium alloy to adiabatic shearing has been studied by means of associating their mechanical response under high strain rate with micro-analysis. Results show that the sensitivities of the different directions to adiabatic shearing are highly anisotropy. RD has the lowest sensitivity to adiabatic shearing and ND has the highest to adiabatic shearing. The differences of susceptibility of the different directions of deformed contexture to adiabatic shearing are caused by different thermal softening effect in the course of dynamic deformation
2011, 40(10):1799-1803.
Abstract:
The dynamic fracture toughness of TC4 titanium alloy in 7 heat-treatment conditions, such as 750 oC, (20-60) oC lower than or 10 oC higher than the phase transformation temperature, was tested by means of instrumented impact method. Combined with both metallography and fractographs, the influence of volume of primary α phase and ratio of length/width for secondary α phase was studied. Results show that the volume of primary α phase in 47%-50% with short rod-like secondary α phase leads to relatively good dynamic fracture toughness for TC4 titanium alloy with (primary α+βTrans) microstructure under the dynamic loading condition.
The dynamic fracture toughness of TC4 titanium alloy in 7 heat-treatment conditions, such as 750 oC, (20-60) oC lower than or 10 oC higher than the phase transformation temperature, was tested by means of instrumented impact method. Combined with both metallography and fractographs, the influence of volume of primary α phase and ratio of length/width for secondary α phase was studied. Results show that the volume of primary α phase in 47%-50% with short rod-like secondary α phase leads to relatively good dynamic fracture toughness for TC4 titanium alloy with (primary α+βTrans) microstructure under the dynamic loading condition.
2011, 40(10):1804-1807.
Abstract:
(2D-Tif)/Al composites reinforced with TC4 fibers fabric was fabricated by pressure infiltration method for the demand of debris protection of aircrafts. The impact resistance ability, macro-damage characteristic and microstructure evolution principle of the two types of composites were researched by two-stage light gas gun (at a velocity of 2.5 km/s). Results show that the failure characteristics of (2D-Tif)/Al composite targets are comprised of the penetration and the spalling on the back surfaces. The prospection capacity of the composites is twice higher than those of the LF6 alloy. Aluminum alloy matrix are squeezed and deformed seriously near the crater and micro-cracks as well as holes are dominated in the matrix. Analysis show that adiabatic shear band inner the alloy matrix is restrained obviously by the addition of TC4 fibers
(2D-Tif)/Al composites reinforced with TC4 fibers fabric was fabricated by pressure infiltration method for the demand of debris protection of aircrafts. The impact resistance ability, macro-damage characteristic and microstructure evolution principle of the two types of composites were researched by two-stage light gas gun (at a velocity of 2.5 km/s). Results show that the failure characteristics of (2D-Tif)/Al composite targets are comprised of the penetration and the spalling on the back surfaces. The prospection capacity of the composites is twice higher than those of the LF6 alloy. Aluminum alloy matrix are squeezed and deformed seriously near the crater and micro-cracks as well as holes are dominated in the matrix. Analysis show that adiabatic shear band inner the alloy matrix is restrained obviously by the addition of TC4 fibers
2011, 40(10):1808-1811.
Abstract:
Ti-8.15Si alloy was prepared by cold wall induction furnace melting and metal mould casting. The solidification structure characteristics, effects of annealing on the microstructure and the compressive property for the Ti-8.15Si alloy were investigated by OM, XRD, SEM and a multifunctional testing machine. Results show that the Ti-8.15Si alloy presents a eutectic structure composed of αTi and Ti5Si3 compound. The primary Ti5Si3 phases are coarse rod-like, while the eutectic Ti5Si3 phases are finer and dendritic or rod-like, and the cross section is hexagonal. After annealing at 1323 K for 60 min, the coarse rod-like Ti5Si3 phases become small obviously and the dendritic Ti5Si3 phases become discontinuous and fine grains, thus improving the compressive property. As for 120 min, Ti5Si3 grow gradually and a few bulk Ti3Si appears. As for 180 min, more Ti3Si phases are formed and the hardness and the compressive strength increase but the ductility decreases.
Ti-8.15Si alloy was prepared by cold wall induction furnace melting and metal mould casting. The solidification structure characteristics, effects of annealing on the microstructure and the compressive property for the Ti-8.15Si alloy were investigated by OM, XRD, SEM and a multifunctional testing machine. Results show that the Ti-8.15Si alloy presents a eutectic structure composed of αTi and Ti5Si3 compound. The primary Ti5Si3 phases are coarse rod-like, while the eutectic Ti5Si3 phases are finer and dendritic or rod-like, and the cross section is hexagonal. After annealing at 1323 K for 60 min, the coarse rod-like Ti5Si3 phases become small obviously and the dendritic Ti5Si3 phases become discontinuous and fine grains, thus improving the compressive property. As for 120 min, Ti5Si3 grow gradually and a few bulk Ti3Si appears. As for 180 min, more Ti3Si phases are formed and the hardness and the compressive strength increase but the ductility decreases.
2011, 40(10):1812-1816.
Abstract:
The Al3Ti intermetallic compound was fabricated with pure Ti powder and aluminum plate as starting materials by self-developed rotational extrusion equipment. The microstructure of the rotational extrusion alloyed product was observed with scanning electron microscopy and energy dispersive spectrometry, the phase constituent of alloying product was inspected by transmission electron microscopy and X-ray diffraction, and the microhardness was measured. The results show that under the interaction effect of the friction stick shearing and extrusion force, the Ti-Al intermetallic compounds can be synthesized by alloying reaction, and the product is Al3Ti phase intermetallic compound. The size of Al3Ti particles is about 500 nm, and the matrix of aluminum presents a large number of dislocations, which are irregular arrangement of curly state. The average microhardness of alloyed product is 1080 MPa, four times that of matrix.
The Al3Ti intermetallic compound was fabricated with pure Ti powder and aluminum plate as starting materials by self-developed rotational extrusion equipment. The microstructure of the rotational extrusion alloyed product was observed with scanning electron microscopy and energy dispersive spectrometry, the phase constituent of alloying product was inspected by transmission electron microscopy and X-ray diffraction, and the microhardness was measured. The results show that under the interaction effect of the friction stick shearing and extrusion force, the Ti-Al intermetallic compounds can be synthesized by alloying reaction, and the product is Al3Ti phase intermetallic compound. The size of Al3Ti particles is about 500 nm, and the matrix of aluminum presents a large number of dislocations, which are irregular arrangement of curly state. The average microhardness of alloyed product is 1080 MPa, four times that of matrix.
2011, 40(10):1817-1821.
Abstract:
Ag-W alloy contact is one kind of important electrical contact materials, and the separation and recycling of sliver and tungsten from waste Ag-W alloy contact has attracted more and more attention for the resource value and secondary pollution during the recycling process. A novel process about the separation and recycling of sliver and tungsten from waste Ag-W alloy contact has been proposed, which includes 4 steps of first leaching silver, roasting, secondary leaching silver and ammonia leaching. The result shows that the recovery rate of Ag and W is higher than 99%, and 0.3-0.6 μm superfine silver powders and pure WO3 powders can be obtained during the recycling process.
Ag-W alloy contact is one kind of important electrical contact materials, and the separation and recycling of sliver and tungsten from waste Ag-W alloy contact has attracted more and more attention for the resource value and secondary pollution during the recycling process. A novel process about the separation and recycling of sliver and tungsten from waste Ag-W alloy contact has been proposed, which includes 4 steps of first leaching silver, roasting, secondary leaching silver and ammonia leaching. The result shows that the recovery rate of Ag and W is higher than 99%, and 0.3-0.6 μm superfine silver powders and pure WO3 powders can be obtained during the recycling process.
2011, 40(10):1822-1826.
Abstract:
Porous titanium based alloys containing 8 wt% and 12 wt% cobalt elements were prepared by gelcasting methods. The concentration of dispersant for obtain the stable suspension slurry were studied. The microstructure, the total porosity and the mechanical properties of the sintered porous Ti-Co alloys were investigated by scaning electronic microscopy, X-ray diffraction, compression and bending tests. The results show that 1 wt% of the optimal dispersant amount is selected, at which viscosity of the suspension slurry is low. Open and closed three-dimensional pore morphologies and total porosity around 50% can be achieved. In contrast to porous Ti by gelcasting available before, porous Ti-Co alloys present excellent properties. The compressive strength ranging from 68-378 MPa, the bending strength ranging from 53.68-169.17 MPa and Young's modulus ranging from 7-21 GPa. In this study, porous Ti-8Co alloy (33 vol%) which have great properties matching adult bone, therefore being suited for medical applications.
Porous titanium based alloys containing 8 wt% and 12 wt% cobalt elements were prepared by gelcasting methods. The concentration of dispersant for obtain the stable suspension slurry were studied. The microstructure, the total porosity and the mechanical properties of the sintered porous Ti-Co alloys were investigated by scaning electronic microscopy, X-ray diffraction, compression and bending tests. The results show that 1 wt% of the optimal dispersant amount is selected, at which viscosity of the suspension slurry is low. Open and closed three-dimensional pore morphologies and total porosity around 50% can be achieved. In contrast to porous Ti by gelcasting available before, porous Ti-Co alloys present excellent properties. The compressive strength ranging from 68-378 MPa, the bending strength ranging from 53.68-169.17 MPa and Young's modulus ranging from 7-21 GPa. In this study, porous Ti-8Co alloy (33 vol%) which have great properties matching adult bone, therefore being suited for medical applications.
2011, 40(10):1827-1831.
Abstract:
Using ascorbic acid (C6H8O6) as the reducing agent and AgNO3 as the source of Ag, the ultrafine silver powders were prepared by a liquid phase reduction method. By means of the orthogonal design method of six factors and five levels, the effects of the following factors on the dispersion and particles size of silver powders were studied, such as the concentration of AgNO3, the concentration of C6H8O6, the selection of dispersers, the doses of disperser, pH and the temperature. The optimized conditions for the ultrafine silver powders preparation were obtained. The pure ultrafine silver powders with near-spherical shape and mean diameter of 0.89 μm can be synthesized under the conditions of AgNO3 concentration of 0.15 mol·L-1, C6H8O6 concentration of 0.40 mol·L-1, oleic acid (C18H34O2) as disperser, C18H34O2/AgNO3 mass ratio of 8:100, pH=4 and at 50 oC. The ultrafine silver powders were characterized by scanning electron microscopy (SEM) and XRD
Using ascorbic acid (C6H8O6) as the reducing agent and AgNO3 as the source of Ag, the ultrafine silver powders were prepared by a liquid phase reduction method. By means of the orthogonal design method of six factors and five levels, the effects of the following factors on the dispersion and particles size of silver powders were studied, such as the concentration of AgNO3, the concentration of C6H8O6, the selection of dispersers, the doses of disperser, pH and the temperature. The optimized conditions for the ultrafine silver powders preparation were obtained. The pure ultrafine silver powders with near-spherical shape and mean diameter of 0.89 μm can be synthesized under the conditions of AgNO3 concentration of 0.15 mol·L-1, C6H8O6 concentration of 0.40 mol·L-1, oleic acid (C18H34O2) as disperser, C18H34O2/AgNO3 mass ratio of 8:100, pH=4 and at 50 oC. The ultrafine silver powders were characterized by scanning electron microscopy (SEM) and XRD
2011, 40(10):1832-1835.
Abstract:
Ag-Cu brazing filler were adopted to seal oxygen-permeable membrane ceramics and stainless steel support, and the effect of Cu content on interface microstructure of oxygen-permeable membrane brazed with Ag-Cu brazing filler was investigated. The microstructure of the interface was observed by SEM and the constituent phases were analyzed by EDS. The results show that no elemental interdiffusion occurs in the interface of pure Ag and oxygen-permeable membrane; the addition of 1 at%Cu doesn’t improve the bonding of the interface obviously; when the Cu content reaches 3.3 at%, a reaction layer of about 200 μm in thickness forms on the membrane side due to the diffusion of Cu and Ag, which indicates the good wetting ability and interface bonding between Ag-3.3Cu brazing filler and oxygen-permeable membrane.
Ag-Cu brazing filler were adopted to seal oxygen-permeable membrane ceramics and stainless steel support, and the effect of Cu content on interface microstructure of oxygen-permeable membrane brazed with Ag-Cu brazing filler was investigated. The microstructure of the interface was observed by SEM and the constituent phases were analyzed by EDS. The results show that no elemental interdiffusion occurs in the interface of pure Ag and oxygen-permeable membrane; the addition of 1 at%Cu doesn’t improve the bonding of the interface obviously; when the Cu content reaches 3.3 at%, a reaction layer of about 200 μm in thickness forms on the membrane side due to the diffusion of Cu and Ag, which indicates the good wetting ability and interface bonding between Ag-3.3Cu brazing filler and oxygen-permeable membrane.
2011, 40(10):1836-1839.
Abstract:
Three types of ZrAlNiCu metallic glasses were successfully fabricated through vacuum arc melting under an argon atmosphere with suction-casting into a water-cooling-copper mold. The compressive mechanical properties of the three metallic glasses were tested using an Instron-3369 mechanical testing machine, and the compressive fracture surface was investigated by FEI Nano230 scanning electron microscope (SEM). Results show that increasing the Ni content and decreasing the Cu content will decrease the fracture strength and elastic modulus of the metallic glasses, and change the “vein-type” fracture surface to a completely brittle characteristic. The increase in the Ni content and decrease in the Cu content decrease the density of the free volume, degrade the deformation ability, increase the local deformation degree, and thus, decrease the fracture strength, plasticity and elastic modulus of the ZrAlNiCu metallic glass.
Three types of ZrAlNiCu metallic glasses were successfully fabricated through vacuum arc melting under an argon atmosphere with suction-casting into a water-cooling-copper mold. The compressive mechanical properties of the three metallic glasses were tested using an Instron-3369 mechanical testing machine, and the compressive fracture surface was investigated by FEI Nano230 scanning electron microscope (SEM). Results show that increasing the Ni content and decreasing the Cu content will decrease the fracture strength and elastic modulus of the metallic glasses, and change the “vein-type” fracture surface to a completely brittle characteristic. The increase in the Ni content and decrease in the Cu content decrease the density of the free volume, degrade the deformation ability, increase the local deformation degree, and thus, decrease the fracture strength, plasticity and elastic modulus of the ZrAlNiCu metallic glass.
2011, 40(10):1840-1843.
Abstract:
A series of (Fe40Co40B20)1-xNix magnetic thin films (x is atomic fraction) were synthesized by magnetron sputtering (RF), and the electromagnetic and microwave properties were investigated. The results show that the microstructure and electromagnetic properties of the films can be altered by varying the content of Ni addition and suitable process parameters. Excellent microwave properties and high resistivity are achieved in the (Fe40Co40B20)0.91Ni9 thin film. The film has the saturation magnetization 4πMs of 2.21 T, the real part of complex permeability μ' is larger than 195 at 0.5-3.0 GHz fFMR reaches to 3.16 GHz, and the resistivity is 276 μΩ·cm. Therefore, the presented films have the potential for the electromagnetic device design in the GHz frequency range.
A series of (Fe40Co40B20)1-xNix magnetic thin films (x is atomic fraction) were synthesized by magnetron sputtering (RF), and the electromagnetic and microwave properties were investigated. The results show that the microstructure and electromagnetic properties of the films can be altered by varying the content of Ni addition and suitable process parameters. Excellent microwave properties and high resistivity are achieved in the (Fe40Co40B20)0.91Ni9 thin film. The film has the saturation magnetization 4πMs of 2.21 T, the real part of complex permeability μ' is larger than 195 at 0.5-3.0 GHz fFMR reaches to 3.16 GHz, and the resistivity is 276 μΩ·cm. Therefore, the presented films have the potential for the electromagnetic device design in the GHz frequency range.
2011, 40(10):1844-1847.
Abstract:
Substitution of Ti-Cu-layered composite materials for single-titanium substrates in traditional titanium electrodes was proposed, and the different performances between the novel electrode and the traditional Ti coated electrodes were investigated. The potential distribution over the electrode surface and linear scanning voltammetry curves were analyzed. The results show that the Ti-Cu-based coated electrode possesses higher conductivity due to its new substrate material, which is conducive to both potential distribution and current distribution over the electrode surface. The Ti-Cu-based coated electrode has better electrocatalytic activity, as well as excellent reaction stability under high-current density. When used in electrolysis industry, the novel electrode can reduce the electrolysis voltage and increase current density, thus enhancing the current efficiency and the productivity.：Substitution of Ti-Cu-layered composite materials for single-titanium substrates in traditional titanium electrodes was proposed, and the different performances between the novel electrode and the traditional Ti coated electrodes were investigated. The potential distribution over the electrode surface and linear scanning voltammetry curves were analyzed. The results show that the Ti-Cu-based coated electrode possesses higher conductivity due to its new substrate material, which is conducive to both potential distribution and current distribution over the electrode surface. The Ti-Cu-based coated electrode has better electrocatalytic activity, as well as excellent reaction stability under high-current density. When used in electrolysis industry, the novel electrode can reduce the electrolysis voltage and increase current density, thus enhancing the current efficiency and the productivity.
Substitution of Ti-Cu-layered composite materials for single-titanium substrates in traditional titanium electrodes was proposed, and the different performances between the novel electrode and the traditional Ti coated electrodes were investigated. The potential distribution over the electrode surface and linear scanning voltammetry curves were analyzed. The results show that the Ti-Cu-based coated electrode possesses higher conductivity due to its new substrate material, which is conducive to both potential distribution and current distribution over the electrode surface. The Ti-Cu-based coated electrode has better electrocatalytic activity, as well as excellent reaction stability under high-current density. When used in electrolysis industry, the novel electrode can reduce the electrolysis voltage and increase current density, thus enhancing the current efficiency and the productivity.：Substitution of Ti-Cu-layered composite materials for single-titanium substrates in traditional titanium electrodes was proposed, and the different performances between the novel electrode and the traditional Ti coated electrodes were investigated. The potential distribution over the electrode surface and linear scanning voltammetry curves were analyzed. The results show that the Ti-Cu-based coated electrode possesses higher conductivity due to its new substrate material, which is conducive to both potential distribution and current distribution over the electrode surface. The Ti-Cu-based coated electrode has better electrocatalytic activity, as well as excellent reaction stability under high-current density. When used in electrolysis industry, the novel electrode can reduce the electrolysis voltage and increase current density, thus enhancing the current efficiency and the productivity.
2011, 40(10):1848-1851.
Abstract:
Copper indium gallium selenium (CIGS) films were prepared on quartz substrate within 40-600 °C by PLD method, and characterized by spectrophotometer, XRD, SEM and EDS. Results show that the films are grown with single chalcopyrite structure preferential (112) orientation, within 40-400 °C, the grains size, crystallization quality are almost not influenced with temperature, while the temperature reached 600 °C, grains size and crystal quality, the infrared light transmittance etc. increased significantly. These phenomena are mainly attributed to the effect of substrate temperature on the diffusion of the Ga elements, at high temperature, the diffusion is sufficient and the crystal structure reorganization is finished. The relationship between Se composition and temperature was also analyzed.
Copper indium gallium selenium (CIGS) films were prepared on quartz substrate within 40-600 °C by PLD method, and characterized by spectrophotometer, XRD, SEM and EDS. Results show that the films are grown with single chalcopyrite structure preferential (112) orientation, within 40-400 °C, the grains size, crystallization quality are almost not influenced with temperature, while the temperature reached 600 °C, grains size and crystal quality, the infrared light transmittance etc. increased significantly. These phenomena are mainly attributed to the effect of substrate temperature on the diffusion of the Ga elements, at high temperature, the diffusion is sufficient and the crystal structure reorganization is finished. The relationship between Se composition and temperature was also analyzed.
35 Effects of Melt-Spinning Speed on Microstructure and Magnetic Properties of Nd10Fe81Co3B6 Ribbons
2011, 40(10):1852-1854.
Abstract:
Nd10Fe81Co3B ribbons were prepared by melt-spinning method at different melt-spinning speeds, and the effects of melt-spinning speeds on the microstructure and magnetic properties of Nd10Fe81Co3B ribbons were studied. The results show that the content of amorphous phase is increased with increasing the melt-spinning speed. After annealed at 800 °C for 10 min, the ribbons melt-spun at 15 m/s speeds are consisted of Nd2(Fe,Co)14B and Fe7Co3. The medium grain size of Nd2(Fe,Co)14B is greater than 50 nm, however that of Fe7Co3 size is smaller than 25 nm. Inter-grains exchange coupling interaction is weakened; there are high content of amorphous phase in the ribbons melt-spun at 50 m/s, which makes the remanence reduce, and the coercivity didn’t obviously reduce. The ribbons melt-spun at 50 m/s had a optimum crystallization, and the inter-grains exchange coupling interaction acted well. Their magnetic properties are Hc=249 928 A/m, Mr=84.3 A·m2/kg. Furthermore, Curie temperature of the ribbons with different melt-spinning speeds are basically same, it’s about 630 K.
Nd10Fe81Co3B ribbons were prepared by melt-spinning method at different melt-spinning speeds, and the effects of melt-spinning speeds on the microstructure and magnetic properties of Nd10Fe81Co3B ribbons were studied. The results show that the content of amorphous phase is increased with increasing the melt-spinning speed. After annealed at 800 °C for 10 min, the ribbons melt-spun at 15 m/s speeds are consisted of Nd2(Fe,Co)14B and Fe7Co3. The medium grain size of Nd2(Fe,Co)14B is greater than 50 nm, however that of Fe7Co3 size is smaller than 25 nm. Inter-grains exchange coupling interaction is weakened; there are high content of amorphous phase in the ribbons melt-spun at 50 m/s, which makes the remanence reduce, and the coercivity didn’t obviously reduce. The ribbons melt-spun at 50 m/s had a optimum crystallization, and the inter-grains exchange coupling interaction acted well. Their magnetic properties are Hc=249 928 A/m, Mr=84.3 A·m2/kg. Furthermore, Curie temperature of the ribbons with different melt-spinning speeds are basically same, it’s about 630 K.
2011, 40(10):1855-1858.
Abstract:
Effects of different hot rolling temperatures on the second phase particles of zirconium alloy were investigated under the same working rate to determine the optimum processing technique. NZ2 plates of 1.4 mm thickness were prepared at different hot rolling temperatures of 800, 700, 650 and 610 oC according to the processing parameters of commercial-scale ingot sheets and then were corroded in super-heated steam at 400 oC, 10.3 MPa. Their hydrogen content was measured at various time. The distribution and variety of the second phase of the alloys were observed by OM, SEM and TEM. Results show that uniform, fine and diffusive second phase can be obtained by selecting proper hot rolling temperature and therefore zirconium alloy can be prepared with high corrosion resistance and low hydrogen absorbability.
Effects of different hot rolling temperatures on the second phase particles of zirconium alloy were investigated under the same working rate to determine the optimum processing technique. NZ2 plates of 1.4 mm thickness were prepared at different hot rolling temperatures of 800, 700, 650 and 610 oC according to the processing parameters of commercial-scale ingot sheets and then were corroded in super-heated steam at 400 oC, 10.3 MPa. Their hydrogen content was measured at various time. The distribution and variety of the second phase of the alloys were observed by OM, SEM and TEM. Results show that uniform, fine and diffusive second phase can be obtained by selecting proper hot rolling temperature and therefore zirconium alloy can be prepared with high corrosion resistance and low hydrogen absorbability.
2011, 40(10):1859-1863.
Abstract:
Fluoride-coating was prepared on AZ31B magnesium alloy by an immersion treatment in hydrofluoric acid at room temperature, and the surface morphology, composition, corrosion resistance and degradation mechanism of the coated alloy were studied. The results show that the conversion coating is compact with good bonding to the alloy. The corrosion resistance of the fluoride coated AZ31B alloy is obviously improved, and its degradation in simulated body fluid (SBF) is slow. The pH value of the SBF (the coated alloy immersed in) keeps in a range of 7.5 to 8.8, which can effectively reduce the alkalization caused by the biodegradation of the alloy. The fluoride coating gradually transform into Ca3(PO4)2 in SBF, which will continue protect the alloy from the corrosion.
Fluoride-coating was prepared on AZ31B magnesium alloy by an immersion treatment in hydrofluoric acid at room temperature, and the surface morphology, composition, corrosion resistance and degradation mechanism of the coated alloy were studied. The results show that the conversion coating is compact with good bonding to the alloy. The corrosion resistance of the fluoride coated AZ31B alloy is obviously improved, and its degradation in simulated body fluid (SBF) is slow. The pH value of the SBF (the coated alloy immersed in) keeps in a range of 7.5 to 8.8, which can effectively reduce the alkalization caused by the biodegradation of the alloy. The fluoride coating gradually transform into Ca3(PO4)2 in SBF, which will continue protect the alloy from the corrosion.
2011, 40(10):1864-1866.
Abstract:
A novel templateless AC electrochemical deposition method for controllable synthesis of gold nano/micro wire was proposed. Liner gold nanowires could be obtained by controlling the processing parameters, such as AC frequency, plating solution concentration, etc. Gold wire fabricated by this method could connect the electrodes using oscillograph to monitor the circuit. The TEM characterization results prove the fabricated gold nano/micro wire is of single-crystal structure. The measurement results of the electrical characteristics demonstrate that the gold nano/micro wire has a low resistivity (7.8×10-7 Ω·m). The wire produced by the templateless AC electrochemical deposition method has the application potentials in micro/nano interconnection, bio/chemical sensors etc.
A novel templateless AC electrochemical deposition method for controllable synthesis of gold nano/micro wire was proposed. Liner gold nanowires could be obtained by controlling the processing parameters, such as AC frequency, plating solution concentration, etc. Gold wire fabricated by this method could connect the electrodes using oscillograph to monitor the circuit. The TEM characterization results prove the fabricated gold nano/micro wire is of single-crystal structure. The measurement results of the electrical characteristics demonstrate that the gold nano/micro wire has a low resistivity (7.8×10-7 Ω·m). The wire produced by the templateless AC electrochemical deposition method has the application potentials in micro/nano interconnection, bio/chemical sensors etc.
2011, 40(10):1867-1870.
Abstract:
Sample digestion methods of automobile catalysts were researched, based on a certain ratio of hydrochloric acid, nitric acid, hydrofluoric acid, perchloric acid and sulfuric acid. The content of Pt, Pd and Rh in samples was determined by UV spectrophotometry. The results show that the digestion method with hydrochloric acid, hydrofluoric acid and hydrogen peroxide and adopting a polytetrafluoroethylene (PTFE) digestion tank, is more beneficial to the digestion of Pt, Pd and Rh. The recovery rates of Pt, Pd and Rh are 99.5%, 99.8% and 101.6%, respectively. The relative standard deviation is 3.04% for Pt, 2.71% for Pd and 1.80% for Rh. The method is simple and the result is satisfactory.
Sample digestion methods of automobile catalysts were researched, based on a certain ratio of hydrochloric acid, nitric acid, hydrofluoric acid, perchloric acid and sulfuric acid. The content of Pt, Pd and Rh in samples was determined by UV spectrophotometry. The results show that the digestion method with hydrochloric acid, hydrofluoric acid and hydrogen peroxide and adopting a polytetrafluoroethylene (PTFE) digestion tank, is more beneficial to the digestion of Pt, Pd and Rh. The recovery rates of Pt, Pd and Rh are 99.5%, 99.8% and 101.6%, respectively. The relative standard deviation is 3.04% for Pt, 2.71% for Pd and 1.80% for Rh. The method is simple and the result is satisfactory.
2011, 40(10):1871-1875.
Abstract:
The research states and applications of refractory metals tungsten, molybdenum, tantalum, niobium and rhenium and their alloys and coatings used in spaceflight industry, have been summarized. The kinds, mechanical properties and preparation technologies of the alloys and performances of their coatings have also been introduced. The refractory metals are mainly used as rocket engine and spacecraft structural parts. And the tungsten, molybdenum and their crystals are also used in space dynamical system. The order of the service temperature from high to low in refractory metals and their alloys is same as the melting point order of materials.
The research states and applications of refractory metals tungsten, molybdenum, tantalum, niobium and rhenium and their alloys and coatings used in spaceflight industry, have been summarized. The kinds, mechanical properties and preparation technologies of the alloys and performances of their coatings have also been introduced. The refractory metals are mainly used as rocket engine and spacecraft structural parts. And the tungsten, molybdenum and their crystals are also used in space dynamical system. The order of the service temperature from high to low in refractory metals and their alloys is same as the melting point order of materials.
2011, 40(10):1876-1880.
Abstract:
During the crystallizing process of amorphous melt-spun ribbons of nanocomposite permanent magnetic alloys under normal conditions, α-Fe phase always precipitates preferentially, which will induce coarse grains of α-Fe, and it has been proven to be detrimental to the magnetic properties. To solve this problem, crystallizing behavior and mechanisms of this kind of amorphous melt-spun ribbons under extreme conditions were studied by some researchers recently. In the present paper, these works were reviewed.
During the crystallizing process of amorphous melt-spun ribbons of nanocomposite permanent magnetic alloys under normal conditions, α-Fe phase always precipitates preferentially, which will induce coarse grains of α-Fe, and it has been proven to be detrimental to the magnetic properties. To solve this problem, crystallizing behavior and mechanisms of this kind of amorphous melt-spun ribbons under extreme conditions were studied by some researchers recently. In the present paper, these works were reviewed.
