Hardening effects of sheared precipitates on {1121} twinning in magnesium alloys  

作　　者：Jing Tang Wentao Jiang Qingyuan Wang Xiaobao Tian Dean Wei Haidong Fan 

机构地区：[1]Department of Mechanics,Sichuan University,Chengdu 610065,China [2]School of Mechanics and Engineering,Southwest Jiaotong University,Chengdu 610031,China

出　　处：《Journal of Magnesium and Alloys》2023年第2期580-591,共12页镁合金学报（英文）

基　　金：financial support from National Natural Science Foundation of China (12072211);Sichuan Province Science and Technology Project (2020JDJQ0029)。

摘　　要：The interactions between a plate-like precipitate and two twin boundaries(TBs)({1012},{1121}) in magnesium alloys are studied using molecular dynamics(MD) simulations. The precipitate is not sheared by {1012} TB, but sheared by {1121} TB. Shearing on the(110) plane is the predominant deformation mode in the sheared precipitate. Then, the blocking effects of precipitates with different sizes are studied for {1121} twinning. All the precipitates show a blocking effect on {1121} twinning although they are sheared, while the blocking effects of precipitates with different sizes are different. The blocking effect increases significantly with the increasing precipitate length(in-plane size along TB) and thickness, whereas changes weakly as the precipitate width changes. Based on the revealed interaction mechanisms, a critical twin shear is calculated theoretically by the Eshelby solutions to determine which TB is able to shear the precipitate. In addition, an analytical hardening model of sheared precipitates is proposed by analyzing the force equilibrium during TB-precipitate interactions. This model indicates that the blocking effect depends solely on the area fraction of the precipitate cross-section, and shows good agreement with the current MD simulations. Finally, the blocking effects of plate-like precipitates on the {1012} twinning(non-sheared precipitate), {1121} twinning(sheared precipitate) and basal dislocations(non-sheared precipitate) are compared together. Results show that the blocking effect on {1121} twinning is stronger than that on {1012} twinning, while the effect on basal dislocations is weakest. The precipitate-TB interaction mechanisms and precipitation hardening models revealed in this work are of great significance for improving the mechanical property of magnesium alloys by designing microstructure.

关 键 词：Magnesium alloys Precipitate-twin boundary interactions Sheared precipitate Precipitation hardening model Molecular dynamics simulations 

分 类 号：TG146[一般工业技术—材料科学与工程]