Enhancing strength-ductility synergy in a Mg-Gd-Y-Zr alloy at sub-zero temperatures via high dislocation density and shearable precipitates  

作　　者：Xixi Qi Yangxin Li Xinyu Xu Yuxuan Liu Huan Zhang Qingchun Zhu Gaoming Zhu Jingya Wang Mingxin Huang Xiaoqin Zeng 

机构地区：[1]National Engineering Research Center of Light Alloy Net Forming and State Key Laboratory of Metal Matrix Composite,Shanghai Jiao Tong University,Shanghai 200240,China [2]Department of Mechanical Engineering,The University of Hong Kong,Hong Kong 999077,China

出　　处：《Journal of Materials Science & Technology》2023年第35期123-132,共10页材料科学技术（英文版）

基　　金：We acknowledge Prof.Jian Wang from the University of Nebraska-Lincoln for insightful discussion.This work is financially supported by the National Key R&D Program of China(No.2021YFB3501005);the Space Utilization System of China Manned Space Engineering(No.KJZ-YY-WCL04);the Natural Science Foundation of Shanghai(No.23ZR1431100);the National Natural Science Foundation of China(No.51825101).Shanghai Syn-chrotron Radiation Facility is acknowledged for supporting the syn-chrotron high energy X-ray diffraction experiments at Beam Line No.BL14B1.

摘　　要：The strength-ductility trade-offdilemma is hard to be evaded in high-strength Mg alloys at sub-zero temperatures,especially in the Mg alloys containing a high volume fraction of precipitates.In this paper,we report an enhanced strength-ductility synergy at sub-zero temperatures in an aged Mg-7.37Gd-3.1Y-0.27Zr alloy.The tensile stress-strain curves at room temperature(RT),−70℃ and−196℃ show that the strength increases monotonically with decreasing temperature,but the elongation increases first from RT to−70℃ then declines from−70℃ to−196℃.After systematic investigation of the microstructure evolutions at different deformation temperatures via synchrotron X-ray diffraction,electron backscattered diffraction(EBSD)and transmission electron microscopy(TEM),it is found that a high dislocation density with sufficient<c+a>dislocations promotes good tensile ductility at−70℃,which is attributed to the minimized critical resolved shear stress(CRSS)ratio of non-basal<c+a>to basaldislocations.In ad-dition,more shearable precipitates can further improve the ductility via lengthening the mean free path of dislocation glide.The present work demonstrates that an excellent strength-ductility synergy at sub-zero temperatures can be achieved by introducing a high dislocation density and shearable precipitates in high-strength Mg alloys.

关 键 词：Magnesium alloys Strength-ductility synergy Dislocation density Critical resolved shear stress Shearable precipitate 

分 类 号：TG139[一般工业技术—材料科学与工程]