Microstructure Evolution of Pure Magnesium in ECAP and Effect of temperature on deformed microstructure
Received:September 09, 2018  Revised:September 25, 2018
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KeyWord:pure mg; equal channel angular pressing; microstructure; dynamic recrystallization
GE Jiaqi 河南理工大学 材料科学与工程学院
YANG Wen-peng 河南理工大学 材料科学与工程学院
WANG Shi-meng 河南理工大学 材料科学与工程学院
CUI Hong-bao 河南理工大学 材料科学与工程学院
GUO Xue-feng 河南理工大学 材料科学与工程学院
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      Equal channel angular pressing (ECAP) was performed on pure Mg at the temperature range of 200~300 ℃.The microstructure evolution of pure mg during ECAP process were investigated by optical microscopy(OM) and transmission electron microscopy(TEM).The results show that the recrystallized grain size is determined by strain rate and temperature, a minimum grain size of 25.6 μm is obtained at 200 ℃.After 1/2 pass of ECAP process at 225 ℃, the microstructure prior to shear deformation is consisted of long strips coarse grains and twins. The microstructure in the shear zone is mainly shear bands and a large amount of fine grains surrounding the coarse grains. After shear deformation, the microstructure is mainly dynamic recrystallized grains and a small amount of long strips coarse grains. Large amount of basal dislocations are found in the sample, and there are also a small number of non-basal dislocations. At low temperatures ECAP, the dynamic recrystallization mode is comprehensive effect of discontinuous dynamic recrystallization and twinning dynamic recrystallization. With the temperature increasing, the dynamic recrystallization mode turns into discontinuous dynamic recrystallization.