The medium and warm deformation behaviors of an indirect-extruded Mg-8Sn-IAI-IZn alloy were investigated by compression tests at temperatures between 298 and 523 K and strain rates of 0.001-10 s-1. It was found that t...The medium and warm deformation behaviors of an indirect-extruded Mg-8Sn-IAI-IZn alloy were investigated by compression tests at temperatures between 298 and 523 K and strain rates of 0.001-10 s-1. It was found that the twinning-slip transition temperature was strain rate dependent, and all the true stress-true strain curves could be divided into two groups： concave and convex curves. Associated microstructural investigations indicated that the dynamic recrystallization （DRX） be- havior of the alloy varied with deformation conditions. At high strain rate and low temperature, dynamically recrystallized grains preferentially nucleated and developed in the twinned regions, indicating that twinning-induced DRX was dominant. While, at low strain rate, DRX developed extensively at grain boundaries and twins, and the process of twinning contributed to both oriented nucleation and selective growth. For the studied alloy, cracks mainly initiated from the shear band and twinning lamellar over the ranges of temperature and strain rate currently applied.展开更多
The microstructural evolution during directional solidification of the Ni-25%Al(mole fraction) alloy was investigated in the range of growth velocity from 10 to 100 μm/s under a given thermal gradient of 10 K/mm. The...The microstructural evolution during directional solidification of the Ni-25%Al(mole fraction) alloy was investigated in the range of growth velocity from 10 to 100 μm/s under a given thermal gradient of 10 K/mm. The solidification microstructures reveal a transition from γ'-β equilibrium eutectic to γ-β metastable eutectic plus β dendrites. A mixed microstructure of γ'-β and γ-β eutectics produced at a growth velocity of 25 μm/s illustrates that the transition occurs during the competitive growth between γ and γ' phases. The growth temperature for each phase was considered to understand the microstructure selection during solidification. The experimental results show that a phase or a microstructure solidifying with the highest temperature under a given growth condition is preferentially selected upon solidification. In addition, both stable eutectic and metastable eutectic are shown to coexist and simultaneously grow in the velocity range between 25 and 60 μm/s due to their similar growth temperatures.展开更多
基金support by the Fund for Young Scholars of Taiyuan University of Technology (No. 2012L003)the Ph.D. Programs Foundation of Ministry of Education of China (No.20111402110004)
文摘The medium and warm deformation behaviors of an indirect-extruded Mg-8Sn-IAI-IZn alloy were investigated by compression tests at temperatures between 298 and 523 K and strain rates of 0.001-10 s-1. It was found that the twinning-slip transition temperature was strain rate dependent, and all the true stress-true strain curves could be divided into two groups： concave and convex curves. Associated microstructural investigations indicated that the dynamic recrystallization （DRX） be- havior of the alloy varied with deformation conditions. At high strain rate and low temperature, dynamically recrystallized grains preferentially nucleated and developed in the twinned regions, indicating that twinning-induced DRX was dominant. While, at low strain rate, DRX developed extensively at grain boundaries and twins, and the process of twinning contributed to both oriented nucleation and selective growth. For the studied alloy, cracks mainly initiated from the shear band and twinning lamellar over the ranges of temperature and strain rate currently applied.
基金Project(2011-0030801) supported by the National Research Foundation of Korea
文摘The microstructural evolution during directional solidification of the Ni-25%Al(mole fraction) alloy was investigated in the range of growth velocity from 10 to 100 μm/s under a given thermal gradient of 10 K/mm. The solidification microstructures reveal a transition from γ'-β equilibrium eutectic to γ-β metastable eutectic plus β dendrites. A mixed microstructure of γ'-β and γ-β eutectics produced at a growth velocity of 25 μm/s illustrates that the transition occurs during the competitive growth between γ and γ' phases. The growth temperature for each phase was considered to understand the microstructure selection during solidification. The experimental results show that a phase or a microstructure solidifying with the highest temperature under a given growth condition is preferentially selected upon solidification. In addition, both stable eutectic and metastable eutectic are shown to coexist and simultaneously grow in the velocity range between 25 and 60 μm/s due to their similar growth temperatures.
