Mechanical softening of thermoelectric semiconductor Mg2Si from nanotwinning. (December 2018)

• Record Type: Journal Article
• Authors: Li, Guodong; An, Qi; Morozov, Sergey I.; Duan, Bo; Goddard, William A.; Zhai, Pengcheng; Zhang, Qingjie; Jeffrey Snyder, G.
• Is Part Of: Scripta materialia. Number 157(2018)
• Page Start: 90
• Page End: 94
• Publication Date: 2018-12
• Subjects: Nanotwin-induced softening -- Structure - property relation -- Thermoelectric material Mg2Si -- ab-initio calculation; Materials -- Periodicals; Metallurgy -- Periodicals; Metalen; Legeringen; Materiaalkunde; Metals, metalworking and machinery industries; Metals; Electronic journals; 620.11
• DOI: 10.1016/j.scriptamat.2018.08.002
• Languages: English
• ISSNs: 1359-6462

Abstract

Abstract: Nanotwinning exhibits strengthening effects in many metals, semiconductors, and ceramics. However, we show from ab - initio calculations that nanotwins significantly decrease the strength of thermoelectric semiconductor Mg2 Si. The theoretical shear strength of nanotwinned Mg2 Si is found to be 0.93 GPa, much lower than that (6.88 GPa) of flawless Mg2 Si. Stretching the MgSi bond under deformation leads to the structural softening and failure of flawless Mg2 Si. While in nanotwinned Mg2 Si, the MgSi bond at the twin boundary (TB) is expanded to accommodate the structural misfit, weakening the TB rigidity and leading to the low ideal shear strength. Graphical abstract: Unlabelled Image