Recently, a significant progress in coordinating deformation behavior between magnesium alloys was made by Prof. Dong Jie’s team from SJTU Light Alloy Net Forming National Engineering Research Center. The paper titled “Towards high ductility in magnesium alloys - the role of intergranular deformation” was published in International Journal of Plasticity, an international top plastics magazine. Doctoral student Sun Jie is the first author. Prof. Jin Li from SJTU and Prof. Alan Luo from Ohio State University are co-corresponding authors.

In recent years, with the strong support of Academician Ding Wenjiang, Prof. Dong Jie’s team has made a series of achievements in the mechanism of magnesium alloy plastic deformation, and has published 4 papers in International Journal of Plasticity. The other 3 are: Prof. Jin Li’s in-situ study of three-point bending deformation mechanism of magnesium alloy titled “In-situ investigation on the microstructure evolution and plasticity of two magnesium alloys during three-point bending” （https://www.sciencedirect.com/science /article/pii/S0749641915000807）, Dr. Dong Shuai’s paper on cyclic deformation mechanism and fatigue damage of magnesium alloy titled “Magnetic cyclic plastic deformation in ZK60 magnesium alloy” (https://www.sciencedirect. Com/science/article/pii/S0749641916301681), and Dr. Liu Chuanlai’s study on mesoscopic model of plastic deformation of magnesium alloy titled

“An integrated crystal plasticity-phase field model for spatially resolved twin nucleation, propagation, and growth in hexagonal materials” (https://www.sciencedirect.com/science/article/pii/S0749641917307209).

Abstract

This paper investigates the intergranular deformation behavior and its effect on the overall ductility of a Mg-Gd-Y alloy, using in-situ tension in scanning electron microscopy (SEM) combined with electron backscattered diffraction (EBSD) and digital image correlation (DIC) techniques. At regions surrounding grain boundaries, the majority of activated dislocation slip traces were found to form in pairs across grain boundary, and the basal-to-basal (B-B) slip pair is the dominant type. Strain accommodation around the grain boundary interfaces is affected by both Schmid factor in the adjacent grains and the m’ value between these main slip systems. A mk value was proposed in this paper as the maximum value of the product of the Schmid factor and the m’ value of the adjacent grains to measure strain accommodation around the grain boundary interface, where a higher mk value would mean a larger local strain. It is suggested that the overall ductility of a Mg alloy could be evaluated by measuring its average mk value. As an evidence, the Mg-Gd-Y alloy tubes with higher mk value generally show higher elongations during tensile tests in this study.

Translated by Zhang Qianqian

Reviewed by Wang Bingyu