Mechanical softening of thermoelectric semiconductor Mg2Si from nanotwinning

Guodong Li*, Qi An, Sergey I. Morozov, Bo Duan, William A. Goddard, Pengcheng Zhai, Qingjie Zhang, G. Jeffrey Snyder

*Corresponding author for this work

Research output: Contribution to journalArticle

7 Scopus citations

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 Mg2Si. The theoretical shear strength of nanotwinned Mg2Si is found to be 0.93 GPa, much lower than that (6.88 GPa) of flawless Mg2Si. Stretching the Mg–Si bond under deformation leads to the structural softening and failure of flawless Mg2Si. While in nanotwinned Mg2Si, the Mg–Si 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.

Original languageEnglish (US)
Pages (from-to)90-94
Number of pages5
JournalScripta Materialia
Volume157
DOIs
StatePublished - Dec 2018

Keywords

  • Nanotwin-induced softening
  • Structure - property relation
  • Thermoelectric material MgSi
  • ab-initio calculation

ASJC Scopus subject areas

  • Materials Science(all)
  • Condensed Matter Physics
  • Mechanics of Materials
  • Mechanical Engineering
  • Metals and Alloys

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