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Prof. Zeng’s Team Made Important Progress in Mg Alloy Deformation

July 23, 2019      Author: Zhu Gaoming

Recently, the Materials Intelligent Design and Processing Laboratory of SJTU’s National Engineering Research Center for Light Alloy Precision Molding made important research progress in Mg alloy deformation.

The research results were published in the journal International Journal of Plasticity (IF = 5.800, SJTU A+ Journal) with the title "Improving ductility of a Mg alloy via non-basal < a> slip induced by Ca addition". The first author is Zhu Gaoming, a Ph.D. student, and the correspondence authors are Special Researcher Wang Leyun and Prof. Zeng Xiaoqin. Other collaborators come from Nanjing University of Science and Technology, Qinghai University, University of Michigan- Shanghai Jiao Tong University Joint Institute, and SJTU’s School of Materials Science and Engineering. This research is funded by the National Key R&D Program (2016YFB0701203) and the National Natural Science Foundation of China (51631006 and 51671127).

In recent years, with the strong support of Academician Ding Wenjiang, Prof. Zeng Xiaoqin’s team has made a series of important achievements in Mg alloy deformation and published many papers in the Acta Materialia, International Journal of Plasticity, the Scripta Materialia and other journals.

Abstract:

Addition of a small amount of Ca improves the ductility of Mg alloys. However, the mechanism underlying this effect is not well understood. In this work, tensile testing of an extruded Mg0.47 wt% Ca alloy was conducted inside a scanning electron microscope. Electron backscattered diffraction-based slip trace analysis was performed to study in-grain slip activities at 1%, 2%, 4%, 8%, and 16% tensile strain. While the majority of the grains were deformed by basal slip, slip lines from prismatic planes and pyramidal I planes were also frequently observed, and their fractions increased with strain. Ex situ transmission electron microscopy indicated that the pyramidal I slip lines were associated with <a> dislocations instead of <c+a> dislocations. From Schmid factor analysis, the critical resolved shear stresses of prismatic slip and pyramidal <a> slip are approximately twice that of basal slip in this Mg–Ca alloy. The enhanced activity of non-basal <a> slip improved the material's ductility. Our first-principles calculations found that solute Ca atoms would reduce the unstable stacking fault energy for all slip modes.

Translated by Chen Qianqian   Reviewed by Wang Bingyu