The elevated temperature tensile experiments have been carried out on the magnesium alloy and results indicate that the magnesium alloy has excellent superplastic property. Gleebe 1500 testing machine was used in t...The elevated temperature tensile experiments have been carried out on the magnesium alloy and results indicate that the magnesium alloy has excellent superplastic property. Gleebe 1500 testing machine was used in the diffusion bonding experiment on the superplastic magnesium alloy. Then, the shear strength of the joints under different conditions is obtained through shear testing and the optimum processing parameters for the diffusion bonding are achieved. By metallurgical microscope and scanning electron microscope (SEM), it is revealed that the micromechanism of diffusion bonding is the slide of grain boundaries caused by the growth of grains and atom diffusion of the superplastic magnesium alloy.展开更多
Superplasticity of AZ31 Mg alloy at the temperature range of 250-450℃ and stain rate range of 0.7×10^-3- 1.4×10^-1s^-1 was examined through uniaxial tensile test.Optical microscopy （OM）and scanning electr...Superplasticity of AZ31 Mg alloy at the temperature range of 250-450℃ and stain rate range of 0.7×10^-3- 1.4×10^-1s^-1 was examined through uniaxial tensile test.Optical microscopy （OM）and scanning electrom microscopy （SEM）were employed to investigate the morphology of cavities and surface relief near fracture surface,respectively.It is shown that AZ31 Mg alloy starts to exhibit superplasticity for 300℃.The maximum elongation of 362.5% was obtained at 400℃ and strain rate of 0.7×10^-3s^-1,There exist many O-shaped cavities and filaments at the boundaries near fracture surface,The fracture of filaments results in intergranular cavity and the model for the formation of intergranular cavities is proposed .The growth of cavities is plasticity-controlled and the serrated boundaries of intergranular cavities agree with the results of surface relieves.展开更多
High strength, ductility, and superplasticity Mg-6.0%Zn-1.0%Y-0.6%Ce-0.6%Zr（wt%） alloy was prepared by sequentially applying rapid solidification, extrusion, and reciprocating extrusion（REX）. The microstructure of...High strength, ductility, and superplasticity Mg-6.0%Zn-1.0%Y-0.6%Ce-0.6%Zr（wt%） alloy was prepared by sequentially applying rapid solidification, extrusion, and reciprocating extrusion（REX）. The microstructure of the alloy after 2-pass REX consisted of fine grains smaller than 0.7 μm and nanometer strengthening particles. The refined grains resulted from recrystallization during which the nanometer particles played an important role in restrain grain growth. The mechanical properties of the material were investigated at room and elevated temperatures. High tensile yield strength of 336 MPa and elongation of 27% were obtained at room temperature. At elevated temperatures, the highest elongation of 270% was obtained at 250 ℃ and an initial strain rate of 3.3×10^-3 s^-1, and LTS and HSRS were achieved. The high strength, ductility, and superplasticity were attributed to the refined unique microstructure.展开更多
文摘The elevated temperature tensile experiments have been carried out on the magnesium alloy and results indicate that the magnesium alloy has excellent superplastic property. Gleebe 1500 testing machine was used in the diffusion bonding experiment on the superplastic magnesium alloy. Then, the shear strength of the joints under different conditions is obtained through shear testing and the optimum processing parameters for the diffusion bonding are achieved. By metallurgical microscope and scanning electron microscope (SEM), it is revealed that the micromechanism of diffusion bonding is the slide of grain boundaries caused by the growth of grains and atom diffusion of the superplastic magnesium alloy.
文摘Superplasticity of AZ31 Mg alloy at the temperature range of 250-450℃ and stain rate range of 0.7×10^-3- 1.4×10^-1s^-1 was examined through uniaxial tensile test.Optical microscopy （OM）and scanning electrom microscopy （SEM）were employed to investigate the morphology of cavities and surface relief near fracture surface,respectively.It is shown that AZ31 Mg alloy starts to exhibit superplasticity for 300℃.The maximum elongation of 362.5% was obtained at 400℃ and strain rate of 0.7×10^-3s^-1,There exist many O-shaped cavities and filaments at the boundaries near fracture surface,The fracture of filaments results in intergranular cavity and the model for the formation of intergranular cavities is proposed .The growth of cavities is plasticity-controlled and the serrated boundaries of intergranular cavities agree with the results of surface relieves.
基金Funded by the National Natural Foundation of China(No.51571086)China Postdoctoral Science Foundation(No.2013M541973)The Research Fund for Doctoral Program of Henan Polytechnic University(No.B2015-14)
文摘High strength, ductility, and superplasticity Mg-6.0%Zn-1.0%Y-0.6%Ce-0.6%Zr（wt%） alloy was prepared by sequentially applying rapid solidification, extrusion, and reciprocating extrusion（REX）. The microstructure of the alloy after 2-pass REX consisted of fine grains smaller than 0.7 μm and nanometer strengthening particles. The refined grains resulted from recrystallization during which the nanometer particles played an important role in restrain grain growth. The mechanical properties of the material were investigated at room and elevated temperatures. High tensile yield strength of 336 MPa and elongation of 27% were obtained at room temperature. At elevated temperatures, the highest elongation of 270% was obtained at 250 ℃ and an initial strain rate of 3.3×10^-3 s^-1, and LTS and HSRS were achieved. The high strength, ductility, and superplasticity were attributed to the refined unique microstructure.
