Volume 42,Issue 7,2013 Table of Contents
2013, 42(7):1321-1324.
Abstract:
The effect of two rare earth oxides (0, 0.5, 1, 2, 3, 4, 5 mol% CeO2 and 0, 0.5, 1, 2, 3, 4 mol% Y2O3) on hydrogen desorption of NaAlH4 by mechanical milling under an atmosphere of argon was studied. The PCT result reveals that increasing content of CeO2
The effect of two rare earth oxides (0, 0.5, 1, 2, 3, 4, 5 mol% CeO2 and 0, 0.5, 1, 2, 3, 4 mol% Y2O3) on hydrogen desorption of NaAlH4 by mechanical milling under an atmosphere of argon was studied. The PCT result reveals that increasing content of CeO2
2013, 42(7):1325-1327.
Abstract:
Novel stannic oxide nanometer powder has been synthesized via a gas phase detonation reaction with respect to hydrogen gas mixture of oxygen with, stannic chloride as precursor. The detonation products were characterized by powder X-ray diffraction. Trans
Novel stannic oxide nanometer powder has been synthesized via a gas phase detonation reaction with respect to hydrogen gas mixture of oxygen with, stannic chloride as precursor. The detonation products were characterized by powder X-ray diffraction. Trans
2013, 42(7):1328-1331.
Abstract:
Ti6Al4V was chosen as the substrate material, and two modified layers were made by the N+ implantation process and Unbalanced Magnetron Sputtering (UMS) TiN method. The characterization and impact wear behaviors of two modified specimens were studied with
Ti6Al4V was chosen as the substrate material, and two modified layers were made by the N+ implantation process and Unbalanced Magnetron Sputtering (UMS) TiN method. The characterization and impact wear behaviors of two modified specimens were studied with
2013, 42(7):1332-1336.
Abstract:
The novel Ti-6Al-yMo (3≤y≤11) titanium alloys were deposited from blended Ti, Al and Mo powders using the laser solid forming (LSF) process and the microstructure and hardness of as-deposited layers were investigated. Results show that the volume fracti
The novel Ti-6Al-yMo (3≤y≤11) titanium alloys were deposited from blended Ti, Al and Mo powders using the laser solid forming (LSF) process and the microstructure and hardness of as-deposited layers were investigated. Results show that the volume fracti
2013, 42(7):1337-1341.
Abstract:
AZ31B magnesium alloy and 6061 aluminum alloy were joined in stable welding process by cold metal transfer welding with ER4043 as filler metal. The microstructure, morphology and phase composition of the welded joints were studied by OM, SEM, EDX and XRD.
AZ31B magnesium alloy and 6061 aluminum alloy were joined in stable welding process by cold metal transfer welding with ER4043 as filler metal. The microstructure, morphology and phase composition of the welded joints were studied by OM, SEM, EDX and XRD.
2013, 42(7):1342-1346.
Abstract:
Scandium films with thickness of ~ 2~3 μm were deposited on Mo substrates with a surface roughness Rq≈5~8.63 nm. Subsequently, the films were converted to scandium dideuteride (ScD2) in the Sievert’s apparatus. A novel substrate preparation process has
Scandium films with thickness of ~ 2~3 μm were deposited on Mo substrates with a surface roughness Rq≈5~8.63 nm. Subsequently, the films were converted to scandium dideuteride (ScD2) in the Sievert’s apparatus. A novel substrate preparation process has
2013, 42(7):1347-1351.
Abstract:
By analyzing the high temperature TC4-DT titanium alloys’ deformation temperature, strain rate and deformation degree with the parameters of the experimental data flow stress, an adaptive fuzzy-neural network model has been established to predict flow st
By analyzing the high temperature TC4-DT titanium alloys’ deformation temperature, strain rate and deformation degree with the parameters of the experimental data flow stress, an adaptive fuzzy-neural network model has been established to predict flow st
2013, 42(7):1352-1355.
Abstract:
The activation energies of amorphous Fe78Si11B9 and nanocrystalline Fe73.5Cu1B7Si15.5Nb3 alloys were tested by a high-sensitivity differential scanning calorimeter with different heating rates. Kissinger equation was adopted to calculate the activation en
The activation energies of amorphous Fe78Si11B9 and nanocrystalline Fe73.5Cu1B7Si15.5Nb3 alloys were tested by a high-sensitivity differential scanning calorimeter with different heating rates. Kissinger equation was adopted to calculate the activation en
2013, 42(7):1356-1361.
Abstract:
To explore the possibility of near conventional forging of TNM alloys using existing equipment for superalloy, the hot workability of a typical TNM alloy with normal composition of Ti-43Al-4Nb-1Mo-0.1B (at%) was investigated in (α2+γ) dual-phase field.
To explore the possibility of near conventional forging of TNM alloys using existing equipment for superalloy, the hot workability of a typical TNM alloy with normal composition of Ti-43Al-4Nb-1Mo-0.1B (at%) was investigated in (α2+γ) dual-phase field.
2013, 42(7):1362-1366.
Abstract:
The dynamic mechanical properties of 93W-4.9Ni-2.1Fe alloy rod by microwave sintering were investigated under dynamic compression using Split Hopkinson Pressure Bar. The microstructure and micro-hardness of the samples after dynamic compression were analy
The dynamic mechanical properties of 93W-4.9Ni-2.1Fe alloy rod by microwave sintering were investigated under dynamic compression using Split Hopkinson Pressure Bar. The microstructure and micro-hardness of the samples after dynamic compression were analy
2013, 42(7):1367-1371.
Abstract:
Ti6Al4V alloy samples were implanted with silver ion of 1×1017 ion/cm2 firstly under the accelerating voltage of 64.2 keV and then with tantalum ion of 1.5×1017 ion/cm2 under 146.5 keV. The glancing angle X-ray diffraction spectroscopy analysis and X-ra
Ti6Al4V alloy samples were implanted with silver ion of 1×1017 ion/cm2 firstly under the accelerating voltage of 64.2 keV and then with tantalum ion of 1.5×1017 ion/cm2 under 146.5 keV. The glancing angle X-ray diffraction spectroscopy analysis and X-ra
2013, 42(7):1372-1376.
Abstract:
The effects of rare earth element Y contents and rolling temperatures on the recrystallization behavior, microstructure and mechanical properties of the AZ31 magnesium alloy sheets were analyzed. The ways of obtaining high toughness and high formability o
The effects of rare earth element Y contents and rolling temperatures on the recrystallization behavior, microstructure and mechanical properties of the AZ31 magnesium alloy sheets were analyzed. The ways of obtaining high toughness and high formability o
2013, 42(7):1377-1381.
Abstract:
In-situ TiC/Al-4.5Cu composites were prepared by direct reaction synthesis (DRS). The effects of Mg amount on the microstructure and tensile properties of the in-situ TiC/Al-4.5Cu composites were investigated by means of OM and TEM. The results show that
In-situ TiC/Al-4.5Cu composites were prepared by direct reaction synthesis (DRS). The effects of Mg amount on the microstructure and tensile properties of the in-situ TiC/Al-4.5Cu composites were investigated by means of OM and TEM. The results show that
2013, 42(7):1382-1386.
Abstract:
The compression behavior of U-Ti alloy was investigated over a wide range of strain rates from 10-3 to 103 s-1 by static compression tests and split hopkinson pressure bar (SHPB). Combined with the strain frozen technique and the optical micrography, the
The compression behavior of U-Ti alloy was investigated over a wide range of strain rates from 10-3 to 103 s-1 by static compression tests and split hopkinson pressure bar (SHPB). Combined with the strain frozen technique and the optical micrography, the
2013, 42(7):1387-1392.
Abstract:
The ingot of Nb-Ti-Cr-Si based ultrahigh temperature alloy was prepared by vacuum consumable arc melting, and the ambient mechanical properties of the alloy were measured. The results show that the chemical components are distributed uniformly at differen
The ingot of Nb-Ti-Cr-Si based ultrahigh temperature alloy was prepared by vacuum consumable arc melting, and the ambient mechanical properties of the alloy were measured. The results show that the chemical components are distributed uniformly at differen
2013, 42(7):1393-1397.
Abstract:
The compressive properties of Mg-3Al-2Zn-2Y alloy at the strain rates from 0.001 to 4800 s-1 at room temperature were studied. Results show that for the alloy compressed at 1300 s-1, the dislocation slip between its basal and the non-basal produces the mi
The compressive properties of Mg-3Al-2Zn-2Y alloy at the strain rates from 0.001 to 4800 s-1 at room temperature were studied. Results show that for the alloy compressed at 1300 s-1, the dislocation slip between its basal and the non-basal produces the mi
2013, 42(7):1398-1401.
Abstract:
The kinetics curves of deuterium desorption from palladium deuteride was measured in the temperature range frm 25 to 50 ?C. The results show that deuterium could be desorbed fast from palladium deuteride around room temperature. The desorption rate increa
The kinetics curves of deuterium desorption from palladium deuteride was measured in the temperature range frm 25 to 50 ?C. The results show that deuterium could be desorbed fast from palladium deuteride around room temperature. The desorption rate increa
2013, 42(7):1402-1406.
Abstract:
The microarc oxidation (MAO) composite coating containing Cr2O3 microparticles on Ti6Al4V alloy was prepared by co-deposition in the electrolyte with Cr2O3 microparticles addition. The growing characters of the composite coating and deposition styles of C
The microarc oxidation (MAO) composite coating containing Cr2O3 microparticles on Ti6Al4V alloy was prepared by co-deposition in the electrolyte with Cr2O3 microparticles addition. The growing characters of the composite coating and deposition styles of C
19 Dislocation Refinement Mechanism of High Stacking Fault Energy 7003 Al Alloy during ECAP Deformation
2013, 42(7):1407-1410.
Abstract:
Ultrafine grained (UFG) Al 7003 alloy with sizes ranging from 200 nm to a few nanometers was prepared by four passes equal channel angular pressing (ECAP) at room temperature (Bc). The evolution of microstructures of 7003 Al alloy during ECAP deformation
Ultrafine grained (UFG) Al 7003 alloy with sizes ranging from 200 nm to a few nanometers was prepared by four passes equal channel angular pressing (ECAP) at room temperature (Bc). The evolution of microstructures of 7003 Al alloy during ECAP deformation
2013, 42(7):1411-1417.
Abstract:
Octadecanethiol (C18SH) self-assembled monolayers (SAM) were prepared on the silver coin surface. The anti-tarnish characteristics of C18SH SAMs were investigated in 0.5 mol/L NaCl+0.01 mol/L Na2S solution by an electrochemical technique. The results indi
Octadecanethiol (C18SH) self-assembled monolayers (SAM) were prepared on the silver coin surface. The anti-tarnish characteristics of C18SH SAMs were investigated in 0.5 mol/L NaCl+0.01 mol/L Na2S solution by an electrochemical technique. The results indi
2013, 42(7):1418-1422.
Abstract:
Chemical composition and corrosion product of the Northern Song Dynasty Emperor Asoka Pagoda substrate were studied for the first time since it was unearthed from the Changgan Temple underground palace of Nanjing in 2008. Silver samples based on the compo
Chemical composition and corrosion product of the Northern Song Dynasty Emperor Asoka Pagoda substrate were studied for the first time since it was unearthed from the Changgan Temple underground palace of Nanjing in 2008. Silver samples based on the compo
2013, 42(7):1423-1428.
Abstract:
The intermediate annealed microstructure evolution in GH738 alloy after different rolling reductions was studied by OM, SEM, EBSD and HV tester. Results show that the strain hardening is mainly affected by rolling reduction. With different cold deformation degrees, austenite recrystallization does not occur when the annealing temperature is 1000 oC. The uniform, fine and equiaxed grains are obtained when annealing at 1040~1080 oC. The cold working constitutive equation and the recrystallization grain growth equation of GH738 alloy are established
The intermediate annealed microstructure evolution in GH738 alloy after different rolling reductions was studied by OM, SEM, EBSD and HV tester. Results show that the strain hardening is mainly affected by rolling reduction. With different cold deformation degrees, austenite recrystallization does not occur when the annealing temperature is 1000 oC. The uniform, fine and equiaxed grains are obtained when annealing at 1040~1080 oC. The cold working constitutive equation and the recrystallization grain growth equation of GH738 alloy are established
2013, 42(7):1429-1432.
Abstract:
W-ZrC alloy samples were prepared by the powder metallurgy method, and the influence of the addition of ZrC particles on the microstructure and tensile properties of W-ZrC alloys was studied. The results indicate that the relative density and tensile strength of W alloys are effectively increased by ZrC particles. The second phase particles containing W, Zr, C and O in the alloy are formed with ZrC addition. The grain size of the alloy is decreased with the increase of the ZrC content since the second phase particles can inhibit the grain growth. On the other hand, a mixed fracture mode consisting of intergranular and transgranular fractures is observed with the increase of the ZrC content in tungsten-matrix.
W-ZrC alloy samples were prepared by the powder metallurgy method, and the influence of the addition of ZrC particles on the microstructure and tensile properties of W-ZrC alloys was studied. The results indicate that the relative density and tensile strength of W alloys are effectively increased by ZrC particles. The second phase particles containing W, Zr, C and O in the alloy are formed with ZrC addition. The grain size of the alloy is decreased with the increase of the ZrC content since the second phase particles can inhibit the grain growth. On the other hand, a mixed fracture mode consisting of intergranular and transgranular fractures is observed with the increase of the ZrC content in tungsten-matrix.
2013, 42(7):1433-1438.
Abstract:
Based on the Markov Chain in Probability Theory and the Bragg-Williams-type equations for equilibrium defect concentrations, the occupancy probability equations and transfer probability of describing antisite defect have been established. At the same time, antisite and vacant site defect concentrations' equations have also been derived. Using the established equations, the transfer probability and the first-principles plane-wave pseudopotential method, the various point defects of NiAl were studied. It is proved from the calculation and the electron structure that the occupancy probability of antisite defect obeys Fermi-Dirac statistics and when the temperature changes from 800 to 1300 K with Ni:Al=1, NiAl anti-site probability is more about 106~109 times than AlNi antisite probability, which proves that NiAl is the dominant point defect. VNi vacant site concentration is more about 105~107 times than AlNi antisite concentration, while NiAl antisite concentration is more about 106~1010 times than VAl vacant site concentration
Based on the Markov Chain in Probability Theory and the Bragg-Williams-type equations for equilibrium defect concentrations, the occupancy probability equations and transfer probability of describing antisite defect have been established. At the same time, antisite and vacant site defect concentrations' equations have also been derived. Using the established equations, the transfer probability and the first-principles plane-wave pseudopotential method, the various point defects of NiAl were studied. It is proved from the calculation and the electron structure that the occupancy probability of antisite defect obeys Fermi-Dirac statistics and when the temperature changes from 800 to 1300 K with Ni:Al=1, NiAl anti-site probability is more about 106~109 times than AlNi antisite probability, which proves that NiAl is the dominant point defect. VNi vacant site concentration is more about 105~107 times than AlNi antisite concentration, while NiAl antisite concentration is more about 106~1010 times than VAl vacant site concentration
2013, 42(7):1439-1444.
Abstract:
(Cu50Zr50)92Al8 metallic glass exhibited excellent superplasticity and diffusion bonding was succeeded in in the supercooled liquid region. The range of super-cooled liquid region is determined as 68 oC according to DSC curves. Through true stress-strain curves the experiment parameters of superplastic and diffusion bonding (SPF/DB) are chosen as bonding pressure of 200 MPa and bonding temperature of 470~490 oC. XRD patterns show that the metallic glasses after SPF/DB are partially crystallized and the hardness is enhanced. Three-point bending tests were conducted on samples after SPF/DB to fracture using a universal testing machine, and the bonding quality was discussed through the fracture surface analysis. Keeping the pressure a constant of 200 MPa, the metallic glasses after superplastic and diffusion bonding is best bonded when the temperature is 480 oC and the bonding time is 3 h.
(Cu50Zr50)92Al8 metallic glass exhibited excellent superplasticity and diffusion bonding was succeeded in in the supercooled liquid region. The range of super-cooled liquid region is determined as 68 oC according to DSC curves. Through true stress-strain curves the experiment parameters of superplastic and diffusion bonding (SPF/DB) are chosen as bonding pressure of 200 MPa and bonding temperature of 470~490 oC. XRD patterns show that the metallic glasses after SPF/DB are partially crystallized and the hardness is enhanced. Three-point bending tests were conducted on samples after SPF/DB to fracture using a universal testing machine, and the bonding quality was discussed through the fracture surface analysis. Keeping the pressure a constant of 200 MPa, the metallic glasses after superplastic and diffusion bonding is best bonded when the temperature is 480 oC and the bonding time is 3 h.
2013, 42(7):1445-1449.
Abstract:
Magnesium based hydrogen storage nanomaterials, Mg-H and MgEr-H, were prepared through the DC arc plasma method followed by hydrogenation under high hydrogen pressure. The phase composition and dehydriding properties of the hydrogenated nanopowders were analyzed. It is revealed that Er addition can effectively increase the hydrogen absorption percentage of Mg powder and reduce the dehydriding temperature. The thermal decomposition behaviors of pure ammonium perchlorate (AP) and AP with the presence of the magnesium based hydrogen storage nanomaterials have been investigated by simultaneous thermal analysis (TG-DSC). The results show that both Mg-H and MgEr-H can promote the thermal decomposition of AP, including the low temperature reaction and the high temperature reaction. Particularly for the high temperature decomposition, the temperature can be decreased by 80 oC. The decomposition heat of AP is increased greatly, around twice of that of the pure AP, and the reaction rate is also much faster. Therefore, the magnesium based hydrogen storage nanomaterials with rare earth addition are good catalysts for the decomposition of AP
Magnesium based hydrogen storage nanomaterials, Mg-H and MgEr-H, were prepared through the DC arc plasma method followed by hydrogenation under high hydrogen pressure. The phase composition and dehydriding properties of the hydrogenated nanopowders were analyzed. It is revealed that Er addition can effectively increase the hydrogen absorption percentage of Mg powder and reduce the dehydriding temperature. The thermal decomposition behaviors of pure ammonium perchlorate (AP) and AP with the presence of the magnesium based hydrogen storage nanomaterials have been investigated by simultaneous thermal analysis (TG-DSC). The results show that both Mg-H and MgEr-H can promote the thermal decomposition of AP, including the low temperature reaction and the high temperature reaction. Particularly for the high temperature decomposition, the temperature can be decreased by 80 oC. The decomposition heat of AP is increased greatly, around twice of that of the pure AP, and the reaction rate is also much faster. Therefore, the magnesium based hydrogen storage nanomaterials with rare earth addition are good catalysts for the decomposition of AP
2013, 42(7):1450-1453.
Abstract:
Mn1.1Fe0.9P0.8Ge0.2Bx (x=0, 0.02, 0.03, 0.04) compounds were prepared by mechanical milling and subsequent spark plasma sintering (SPS) technique. Their crystal structure was investigated by XRD and the magneticaloric properties were measured by DSC and VSM. Results show that Mn1.1Fe0.9P0.8Ge0.2Bx (x=0, 0.02, 0.03, 0.04) compounds possess a hexagonal Fe2P-type crystal structure. The lattice parameters a and c are changed noticeably with the increase of B, and c/a ratio decreases firstly and then increases. There is a nonlinear relationship between Curie temperature as well as the entropy change and the content of B. The compound achieves the best magneticaloric properties in this system when x=0.02. The Curie temperature increases from 253 K for x=0 to 263 K, and thermal hysteresis decreases from 23 K to 19 K. The maximum value of the magnetic entropy change increases from 28.7 to 32.6 J/kg·K for a field change from 0 to 2 T
Mn1.1Fe0.9P0.8Ge0.2Bx (x=0, 0.02, 0.03, 0.04) compounds were prepared by mechanical milling and subsequent spark plasma sintering (SPS) technique. Their crystal structure was investigated by XRD and the magneticaloric properties were measured by DSC and VSM. Results show that Mn1.1Fe0.9P0.8Ge0.2Bx (x=0, 0.02, 0.03, 0.04) compounds possess a hexagonal Fe2P-type crystal structure. The lattice parameters a and c are changed noticeably with the increase of B, and c/a ratio decreases firstly and then increases. There is a nonlinear relationship between Curie temperature as well as the entropy change and the content of B. The compound achieves the best magneticaloric properties in this system when x=0.02. The Curie temperature increases from 253 K for x=0 to 263 K, and thermal hysteresis decreases from 23 K to 19 K. The maximum value of the magnetic entropy change increases from 28.7 to 32.6 J/kg·K for a field change from 0 to 2 T
2013, 42(7):1459-1463.
Abstract:
Mg85-Nix/MWNTs15-x (x=3, 6, 9, 12, mass fraction) alloys were prepared from Mg and multi-wall carbon nanotubes supported nickel (Ni/MWNTs) by the combined methods of hydriding combustion synthesis (HCS) and mechanical milling (MM). The crystal structures, surface morphologies and hydriding/dehydriding properties of the products were investigated by means of X-ray diffraction (XRD), transmission electron microscopy (TEM), scanning electron microscopy (SEM) and gas reaction controller (GRC), respectively. The results show that the Mg85-Ni9/MWNTs6 alloy possesses the best hydriding/dehydriding properties, which absorbs nearly the saturated hydrogen capacity of 5.68 wt% within 100 s at 373 K, and desorbs 4.31 wt% hydrogen within 1800 s at 523 K. The addition of Ni/MWNTs plays a catalytic role, and it takes the effect on nano-confinement of the Mg2NiH4 particles in the product. There is synergic catalysis between Ni and MWNTs, and when the mass ratio of Ni/MWNTs = 3/2, the hydriding/dehydriding properties of the Mg-Ni/MWNTs system reach the best
Mg85-Nix/MWNTs15-x (x=3, 6, 9, 12, mass fraction) alloys were prepared from Mg and multi-wall carbon nanotubes supported nickel (Ni/MWNTs) by the combined methods of hydriding combustion synthesis (HCS) and mechanical milling (MM). The crystal structures, surface morphologies and hydriding/dehydriding properties of the products were investigated by means of X-ray diffraction (XRD), transmission electron microscopy (TEM), scanning electron microscopy (SEM) and gas reaction controller (GRC), respectively. The results show that the Mg85-Ni9/MWNTs6 alloy possesses the best hydriding/dehydriding properties, which absorbs nearly the saturated hydrogen capacity of 5.68 wt% within 100 s at 373 K, and desorbs 4.31 wt% hydrogen within 1800 s at 523 K. The addition of Ni/MWNTs plays a catalytic role, and it takes the effect on nano-confinement of the Mg2NiH4 particles in the product. There is synergic catalysis between Ni and MWNTs, and when the mass ratio of Ni/MWNTs = 3/2, the hydriding/dehydriding properties of the Mg-Ni/MWNTs system reach the best
2013, 42(7):1464-1468.
Abstract:
The dynamic mechanical properties of equiaxed microstructures of four TC4 titanium alloys were studied with Split Hopkinson pressure bar device under the strain rates 2000, 3000 and 4000 s-1. Curves of dynamic stress-strain under different conditions were obtained. The results show that the dynamic strength, dynamic strain and absorbed energy of equiaxed microstructures of four TC4 titanium alloys all increase with the increasing content of Al and V. The dynamic mechanical properties have been improved. With the increase of interstitial elements content, the dynamic strength and the absorbed energy of the equiaxed microstructure increase while the dynamic strain decreases.
The dynamic mechanical properties of equiaxed microstructures of four TC4 titanium alloys were studied with Split Hopkinson pressure bar device under the strain rates 2000, 3000 and 4000 s-1. Curves of dynamic stress-strain under different conditions were obtained. The results show that the dynamic strength, dynamic strain and absorbed energy of equiaxed microstructures of four TC4 titanium alloys all increase with the increasing content of Al and V. The dynamic mechanical properties have been improved. With the increase of interstitial elements content, the dynamic strength and the absorbed energy of the equiaxed microstructure increase while the dynamic strain decreases.
2013, 42(7):1474-1477.
Abstract:
Wide-gap ternary semiconductor CuIn5Se8 was prepared by the spark plasma sintering technique, and its thermoelectric properties were evaluated at 318~818 K. XRD analysis and band gap measurement indicate that this ternary compound is single phase CuIn5Se8 with its band gap of 1.13 eV, about 0.2 eV smaller than that of In2Se3. The magnitude of Seebeck coefficient decreases from 370.0 to 263.0 mV·K-1, and electrical conductivity increases from 1.44′102 to 2.92′103 W-1·m-1 with the temperature increasing. The thermal conductivity is 0.50 W·K-1·m-1, and the maximum thermoelectric figure of merit ZT is 0.33 at 818 K
Wide-gap ternary semiconductor CuIn5Se8 was prepared by the spark plasma sintering technique, and its thermoelectric properties were evaluated at 318~818 K. XRD analysis and band gap measurement indicate that this ternary compound is single phase CuIn5Se8 with its band gap of 1.13 eV, about 0.2 eV smaller than that of In2Se3. The magnitude of Seebeck coefficient decreases from 370.0 to 263.0 mV·K-1, and electrical conductivity increases from 1.44′102 to 2.92′103 W-1·m-1 with the temperature increasing. The thermal conductivity is 0.50 W·K-1·m-1, and the maximum thermoelectric figure of merit ZT is 0.33 at 818 K
2013, 42(7):1478-1482.
Abstract:
Based on the Miedema’s model, the formation enthalpies of Al3X(Sc, Er, Zr, Li) intermetallics were investigated. Combining with the formation theories of point defects, the formation enthalpies of mono-vacancy and anti-site defect of Al3X intermetallics were also calculated. The results show that the formation enthalpies of Al-Sc system are similar to those of Al-Er system. It indicates that scandium has the similar metallurgical chemical behavior to erbium in aluminum alloys. The mono-vacancy formation enthalpies of X atoms are all higher than those of aluminum atoms in binary compounds for Al-X(Sc, Er, Li) system, and it pointes that aluminum vacancies are formed prior to X(Sc, Er, Li) vacancies in Al-X intermetallics. The formation enthalpies of anti-site defect of Al3X intermetallics follow the sequence of Al3Er> Al3Sc > Al3Zr > Al3Li. Compared with the formation enthalpies of vacancy and anti-site defect of Al3X intermetallics, it is found that the major point defects in Al3Sc, Al3Er and Al3Zr intermetallics are the vacancy and anti-site defect while the major point defect in Al3Li intermetallic is the anti-site defect
Based on the Miedema’s model, the formation enthalpies of Al3X(Sc, Er, Zr, Li) intermetallics were investigated. Combining with the formation theories of point defects, the formation enthalpies of mono-vacancy and anti-site defect of Al3X intermetallics were also calculated. The results show that the formation enthalpies of Al-Sc system are similar to those of Al-Er system. It indicates that scandium has the similar metallurgical chemical behavior to erbium in aluminum alloys. The mono-vacancy formation enthalpies of X atoms are all higher than those of aluminum atoms in binary compounds for Al-X(Sc, Er, Li) system, and it pointes that aluminum vacancies are formed prior to X(Sc, Er, Li) vacancies in Al-X intermetallics. The formation enthalpies of anti-site defect of Al3X intermetallics follow the sequence of Al3Er> Al3Sc > Al3Zr > Al3Li. Compared with the formation enthalpies of vacancy and anti-site defect of Al3X intermetallics, it is found that the major point defects in Al3Sc, Al3Er and Al3Zr intermetallics are the vacancy and anti-site defect while the major point defect in Al3Li intermetallic is the anti-site defect
2013, 42(7):1483-1487.
Abstract:
In order to study the antibacterial properties of bioactive Ti and its mechanism, alkali-heat treated titanium (AH-Ti) was implanted in rat with Staphylococcus aureus suspension to make infection with pure titanium as contrast. The myeloperoxidase activity was detected for evaluating the rat’s inflammation. The concentrations of albumin and fibrinogen were measured by the Enzymemultiplied immunoassay technique. The results show the AH-Ti related inflammation is low along with low albumin and fibrinogen. It is proved AH-Ti has good antibacterial property in vivo. The mechanism for AH-Ti to prevent bacteria adhering to its surface is that its selectively absorbing albumin to its surface weakens the inflammation around the AH-Ti, and the fibrinogen concentration is lower in turn
In order to study the antibacterial properties of bioactive Ti and its mechanism, alkali-heat treated titanium (AH-Ti) was implanted in rat with Staphylococcus aureus suspension to make infection with pure titanium as contrast. The myeloperoxidase activity was detected for evaluating the rat’s inflammation. The concentrations of albumin and fibrinogen were measured by the Enzymemultiplied immunoassay technique. The results show the AH-Ti related inflammation is low along with low albumin and fibrinogen. It is proved AH-Ti has good antibacterial property in vivo. The mechanism for AH-Ti to prevent bacteria adhering to its surface is that its selectively absorbing albumin to its surface weakens the inflammation around the AH-Ti, and the fibrinogen concentration is lower in turn
2013, 42(7):1488-1491.
Abstract:
With variations of initial charging voltage and spraying distance, Mo coatings were prepared by electro-thermal explosion spraying with a constraining tube. The bonding strength, surface morphology and cross-section characteristics of the coating were analyzed. The results show that the coating is formed by liquid metal within a certain spraying distance. Based on the standard of VDI3198, the bonding strength grade of liquid spraying coating belongs to HF-1～HF-3. With the spraying distance increases, the proportion of solid particles in the explosion products increases, the bonding strength grade of the coatings decreases. The increase of initial charging voltage can decrease the maximum spraying distance of the liquid spraying coating
With variations of initial charging voltage and spraying distance, Mo coatings were prepared by electro-thermal explosion spraying with a constraining tube. The bonding strength, surface morphology and cross-section characteristics of the coating were analyzed. The results show that the coating is formed by liquid metal within a certain spraying distance. Based on the standard of VDI3198, the bonding strength grade of liquid spraying coating belongs to HF-1～HF-3. With the spraying distance increases, the proportion of solid particles in the explosion products increases, the bonding strength grade of the coatings decreases. The increase of initial charging voltage can decrease the maximum spraying distance of the liquid spraying coating
2013, 42(7):1492-1496.
Abstract:
W-10Ti alloys were prepared with high purity 6 μm and 300 nm tungsten powder and TiH2 powder as raw materials, which were mixed according to different graded proportions, compacted by the cold isostatic press, and sintered by the liquid sintering method. The density of W-10Ti alloys prepared with tungsten powder of different sizes was measured, and the microstructures and phase constituent of alloys were analyzed by XRD, SEM and TEM. The results show that the density of W-10Ti alloy prepared with all 6 μm tungsten powder and TiH2 powder is only 85%, but W and Ti are distributed uniformly, and almost single phase solid solution is formed in the microstructure. The density of W-10Ti alloy prepared with all 300 nm tungsten powder and TiH2 powder is up to 97%, but more Ti rich solid solution is formed. When W-10Ti alloys prepared with W powder of different sizes and TiH2 powder, the single phase W-rich solid solution in microstructures is increased and the density of alloys are lowered with the decrease of the graded ratio of nanoscale to micronscale tungsten powder. When the graded ratio of nanoscale W to micronscale W is 1:2, the density of W-10Ti alloy is 95%, and more single phase W-rich solid solution is formed.
W-10Ti alloys were prepared with high purity 6 μm and 300 nm tungsten powder and TiH2 powder as raw materials, which were mixed according to different graded proportions, compacted by the cold isostatic press, and sintered by the liquid sintering method. The density of W-10Ti alloys prepared with tungsten powder of different sizes was measured, and the microstructures and phase constituent of alloys were analyzed by XRD, SEM and TEM. The results show that the density of W-10Ti alloy prepared with all 6 μm tungsten powder and TiH2 powder is only 85%, but W and Ti are distributed uniformly, and almost single phase solid solution is formed in the microstructure. The density of W-10Ti alloy prepared with all 300 nm tungsten powder and TiH2 powder is up to 97%, but more Ti rich solid solution is formed. When W-10Ti alloys prepared with W powder of different sizes and TiH2 powder, the single phase W-rich solid solution in microstructures is increased and the density of alloys are lowered with the decrease of the graded ratio of nanoscale to micronscale tungsten powder. When the graded ratio of nanoscale W to micronscale W is 1:2, the density of W-10Ti alloy is 95%, and more single phase W-rich solid solution is formed.
2013, 42(7):1497-1501.
Abstract:
The microstructure and mechanical properties of AZ61-4Si magnesium alloy before and after equal channel angular processing (ECAP) were studied. The results show that Chinese script type Mg2Si phase changes into fine granules after 4-pass ECAP. The matrix α-Mg and divorced eutectic β-Mg17Al12 are also refined. The yield strength, elongation and tensile strength are increased by 128%, 340% and 89%, respectively. The high temperature creep fracture life increases by 8 times and the creep rate is 0.058%/h. Compared with the 4-pass ECAP, the microstructure shows little change after 8-pass ECAP. The yield strength and creep rate of the 8-pass ECAPed alloy are improved while the yield strength, elongation and high temperature creep fracture life are reduced. The modification mechanism for microstructure and mechanical properties of the experimental alloy by ECAP was analyzed
The microstructure and mechanical properties of AZ61-4Si magnesium alloy before and after equal channel angular processing (ECAP) were studied. The results show that Chinese script type Mg2Si phase changes into fine granules after 4-pass ECAP. The matrix α-Mg and divorced eutectic β-Mg17Al12 are also refined. The yield strength, elongation and tensile strength are increased by 128%, 340% and 89%, respectively. The high temperature creep fracture life increases by 8 times and the creep rate is 0.058%/h. Compared with the 4-pass ECAP, the microstructure shows little change after 8-pass ECAP. The yield strength and creep rate of the 8-pass ECAPed alloy are improved while the yield strength, elongation and high temperature creep fracture life are reduced. The modification mechanism for microstructure and mechanical properties of the experimental alloy by ECAP was analyzed
2013, 42(7):1502-1506.
Abstract:
The effects of different cooling rates and reinforcement particle amount on in-situ Cu6Sn5 reinforced composite solder and Ni reinforced composite solder were investigated. The results indicate that the optimal microstructure characterizations, which hold the smallest intermetallic compound (IMC) size and uniform distribution in the solder matrix, of in-situ Cu6Sn5 reinforced composite solder can be achieved under air cooling condition (the cooling rate is 2 oC/s). From the microstructure observation of Ni reinforced composite solder, it is found that big sized IMCs have a significant effect on the growth orientation of ternary eutectic phases. Besides, snow- and leaves-shaped IMCs clusters are found in Sn3.0Ag0.5Cu-0.45Ni solder matrix. When Ni addition increases to 2.0 wt%, dark spots with different sizes and shapes appear uniformly in the solder matrix due to the solid solution effect of Ni in the solder
The effects of different cooling rates and reinforcement particle amount on in-situ Cu6Sn5 reinforced composite solder and Ni reinforced composite solder were investigated. The results indicate that the optimal microstructure characterizations, which hold the smallest intermetallic compound (IMC) size and uniform distribution in the solder matrix, of in-situ Cu6Sn5 reinforced composite solder can be achieved under air cooling condition (the cooling rate is 2 oC/s). From the microstructure observation of Ni reinforced composite solder, it is found that big sized IMCs have a significant effect on the growth orientation of ternary eutectic phases. Besides, snow- and leaves-shaped IMCs clusters are found in Sn3.0Ag0.5Cu-0.45Ni solder matrix. When Ni addition increases to 2.0 wt%, dark spots with different sizes and shapes appear uniformly in the solder matrix due to the solid solution effect of Ni in the solder
2013, 42(7):1507-1512.
Abstract:
The microstructure evolution and property variation of GH80A superalloy after a series of solution heat treatments, single or double aging treatments and long time aging at 550~750 °C for 10 000 h were investigated. Results show that the precipitation temperature of γ′ precipitates is identified as 930~950 °C. The γ′ precipitation could be inhibited by water quenching and cooling medium shows more effects on cooling γ′ precipitate than the solution temperature. Primary γ′ precipitates are strongly influenced by aging temperature and the precipitation of secondary γ′ precipitates just begins at double aging stage. The tensile strength after single/double aging is decreased a little with the solution temperature increasing while the plasticity is increased. Long-time aging microstructure shows good stability below 700 °C and the coarsening of primary γ′ precipitates proceeds by volume diffusion below 700 °C while by interface controlling at 750 °C
The microstructure evolution and property variation of GH80A superalloy after a series of solution heat treatments, single or double aging treatments and long time aging at 550~750 °C for 10 000 h were investigated. Results show that the precipitation temperature of γ′ precipitates is identified as 930~950 °C. The γ′ precipitation could be inhibited by water quenching and cooling medium shows more effects on cooling γ′ precipitate than the solution temperature. Primary γ′ precipitates are strongly influenced by aging temperature and the precipitation of secondary γ′ precipitates just begins at double aging stage. The tensile strength after single/double aging is decreased a little with the solution temperature increasing while the plasticity is increased. Long-time aging microstructure shows good stability below 700 °C and the coarsening of primary γ′ precipitates proceeds by volume diffusion below 700 °C while by interface controlling at 750 °C
2013, 42(7):1513-1516.
Abstract:
Pipes of Zr-Sn-Nb-Fe alloy with the extruding temperature of 600, 620 and 640 oC were prepared by 600 oC extruding, first rolling and second rolling. The microstructure of the alloy was observed by SEM and the evolution of secondary particles and their size statistics were studied. Results show that all the second phases are distributed dispersively under different extruding conditions. The size of secondary particles is increased at higher extruding temperature. During the process of extruding and rolling, the size of the second phase decreases with the increase of processing degree, and the shape of the second phase changes from irregular to globular
Pipes of Zr-Sn-Nb-Fe alloy with the extruding temperature of 600, 620 and 640 oC were prepared by 600 oC extruding, first rolling and second rolling. The microstructure of the alloy was observed by SEM and the evolution of secondary particles and their size statistics were studied. Results show that all the second phases are distributed dispersively under different extruding conditions. The size of secondary particles is increased at higher extruding temperature. During the process of extruding and rolling, the size of the second phase decreases with the increase of processing degree, and the shape of the second phase changes from irregular to globular
2013, 42(7):1517-1521.
Abstract:
Stable concentrated ethanol dispersions of silver nanoparticles with a narrow size distribution were obtained at room temperature. The morphology and optical properties of the silver nanoparticles were characterized by transmission electron microscope (TEM) and visible spectrophotometer (UV-Vis). The results show that the silver particles possess spherical shape with an average diameter of about 4.8 nm with a good dispersion. During the preparation process, poly(vinyl pyrrolidone) (PVP) is used both as a reducing agent and a protecting agent and ethanol is used as a solvent that could rapidly reduce Ag+ in favor of a positively optimum extension of PVP molecule chain which increases the contact chance between PVP and Ag+. Moreover, the PVP molecule of full extension could effectively avoid aggregation of silver nanoparticles
Stable concentrated ethanol dispersions of silver nanoparticles with a narrow size distribution were obtained at room temperature. The morphology and optical properties of the silver nanoparticles were characterized by transmission electron microscope (TEM) and visible spectrophotometer (UV-Vis). The results show that the silver particles possess spherical shape with an average diameter of about 4.8 nm with a good dispersion. During the preparation process, poly(vinyl pyrrolidone) (PVP) is used both as a reducing agent and a protecting agent and ethanol is used as a solvent that could rapidly reduce Ag+ in favor of a positively optimum extension of PVP molecule chain which increases the contact chance between PVP and Ag+. Moreover, the PVP molecule of full extension could effectively avoid aggregation of silver nanoparticles
2013, 42(7):1522-1525.
Abstract:
The effects of rapid quenching, heat treatment and rapid quenching followed by heat treatment (rapid quenching+heat treatment) on the electrochemical performances of (LaCe)1.0(NiCoMnAl)5.0 hydrogen storage alloy were investigated. XRD analyses indicate that all the alloys are of single phase CaCu5-type structure, and the alloy of rapid quenching+heat treatment has the best crystallizability and homogeneity. The results of electrochemical measurement show that compared with the as-cast alloy, the discharge capacity and cycle stability of the heat treated alloy are improved, but the high-rate discharge capability is significantly reduced. The activation performance, discharge capacity, high-rate discharge capability and cycle stability of the quenched alloy are reduced. Rapid quenching+heat treatment obviously improves comprehensive electrochemical performances of the cast alloy, so the alloy of rapid quenching+heat treatment has good activation capability, better discharge capacity (344.7 mA/g), higher capacity retaining rate (S100, 85.67%) and better high-rate discharge capability
The effects of rapid quenching, heat treatment and rapid quenching followed by heat treatment (rapid quenching+heat treatment) on the electrochemical performances of (LaCe)1.0(NiCoMnAl)5.0 hydrogen storage alloy were investigated. XRD analyses indicate that all the alloys are of single phase CaCu5-type structure, and the alloy of rapid quenching+heat treatment has the best crystallizability and homogeneity. The results of electrochemical measurement show that compared with the as-cast alloy, the discharge capacity and cycle stability of the heat treated alloy are improved, but the high-rate discharge capability is significantly reduced. The activation performance, discharge capacity, high-rate discharge capability and cycle stability of the quenched alloy are reduced. Rapid quenching+heat treatment obviously improves comprehensive electrochemical performances of the cast alloy, so the alloy of rapid quenching+heat treatment has good activation capability, better discharge capacity (344.7 mA/g), higher capacity retaining rate (S100, 85.67%) and better high-rate discharge capability
2013, 42(7):1526-1530.
Abstract:
The influencing factors of residual stress of Ti-6.5Al-1Mo-1V-2Zr alloys by laser rapid forming progress were investigated by the hole-drilling method. The results show that laser power, laser scanning speed, powder feed rate and the scanning method significantly affect the residual stress. The greater the laser power, the greater the residual stress. With the increase of scanning speed, residual stress is constantly decreased. With the increase of powder feed rate, there is an increasing trend of residual stress. Among the three scanning methods, the staggered scanning method is preference. Finally, the residual stress at different positions of the forming sample was analyzed, and it is concluded that the middle position is the residual stress peak
The influencing factors of residual stress of Ti-6.5Al-1Mo-1V-2Zr alloys by laser rapid forming progress were investigated by the hole-drilling method. The results show that laser power, laser scanning speed, powder feed rate and the scanning method significantly affect the residual stress. The greater the laser power, the greater the residual stress. With the increase of scanning speed, residual stress is constantly decreased. With the increase of powder feed rate, there is an increasing trend of residual stress. Among the three scanning methods, the staggered scanning method is preference. Finally, the residual stress at different positions of the forming sample was analyzed, and it is concluded that the middle position is the residual stress peak
2013, 42(7):1531-1535.
Abstract:
By introducing atomistic scale studies on solute segregation and its mechanism in recent years, the segregation of interstitial atoms, substitutional atoms and vacancy, and its effect on materials properties are reviewed. The relationship between solute segregation and site preference of alloying elements is discussed. Finally, the physical-based mechanism about the effect of solute segregation on mechanic properties of materials is summed up
By introducing atomistic scale studies on solute segregation and its mechanism in recent years, the segregation of interstitial atoms, substitutional atoms and vacancy, and its effect on materials properties are reviewed. The relationship between solute segregation and site preference of alloying elements is discussed. Finally, the physical-based mechanism about the effect of solute segregation on mechanic properties of materials is summed up
2013, 42(7):1536-1540.
Abstract:
The research on the effects of hydrogen on the amorphous alloys has been reviewed. The effects of hydrogen on the glass forming, mechanical properties, damping properties, and crystallization behavior of amorphous alloys are presented. Finally, the existing problems of the research and the future direction are summarized
The research on the effects of hydrogen on the amorphous alloys has been reviewed. The effects of hydrogen on the glass forming, mechanical properties, damping properties, and crystallization behavior of amorphous alloys are presented. Finally, the existing problems of the research and the future direction are summarized
