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

doi:10.1016/j.scriptamat.2018.08.002

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

Research output: Contribution to journal › Article › peer-review

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 language	English
Pages (from-to)	90-94
Number of pages	5
Journal	Scripta Materialia
Volume	157
DOIs	https://doi.org/10.1016/j.scriptamat.2018.08.002
Publication status	Published - 1 Dec 2018
Externally published	Yes

Keywords

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

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10.1016/j.scriptamat.2018.08.002

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title = "Mechanical softening of thermoelectric semiconductor Mg2Si from nanotwinning",

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.",

keywords = "Nanotwin-induced softening, Structure - property relation, Thermoelectric material MgSi, ab-initio calculation",

author = "Guodong Li and Qi An and Morozov, \{Sergey I.\} and Bo Duan and Goddard, \{William A.\} and Pengcheng Zhai and Qingjie Zhang and \{Jeffrey Snyder\}, G.",

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year = "2018",

month = dec,

day = "1",

doi = "10.1016/j.scriptamat.2018.08.002",

language = "English",

volume = "157",

pages = "90--94",

journal = "Scripta Materialia",

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TY - JOUR

T1 - Mechanical softening of thermoelectric semiconductor Mg2Si from nanotwinning

AU - Li, Guodong

AU - An, Qi

AU - Morozov, Sergey I.

AU - Duan, Bo

AU - Goddard, William A.

AU - Zhai, Pengcheng

AU - Zhang, Qingjie

AU - Jeffrey Snyder, G.

PY - 2018/12/1

Y1 - 2018/12/1

N2 - 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.

AB - 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.

KW - Nanotwin-induced softening

KW - Structure - property relation

KW - Thermoelectric material MgSi

KW - ab-initio calculation

UR - https://www.scopus.com/pages/publications/85051137835

U2 - 10.1016/j.scriptamat.2018.08.002

DO - 10.1016/j.scriptamat.2018.08.002

M3 - Article

AN - SCOPUS:85051137835

SN - 1359-6462

VL - 157

SP - 90

EP - 94

JO - Scripta Materialia

JF - Scripta Materialia

ER -

Mechanical softening of thermoelectric semiconductor Mg₂Si from nanotwinning

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Keywords

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