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...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.展开更多
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)+1 种基金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.
文摘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.
