Nucleation of amorphous shear bands at nanotwins in boron suboxide

被引：74

作者：

An, Qi ^{[1
]}

Reddy, K. Madhav ^{[2
,3
]}

Qian, Jin ^{[1
]}

Hemker, Kevin J. ^{[3
]}

Chen, Ming-Wei ^{[2
]}

Goddard, William A., III ^{[1
]}

机构：

[1] CALTECH, Dept Chem, Mat & Proc Simulat Ctr, 1200 East Calif Blvd, Pasadena, CA 91125 USA

[2] Tohoku Univ, WPI Adv Inst Mat Res, Sendai, Miyagi 9808577, Japan

[3] Johns Hopkins Univ, Dept Mech Engn, Baltimore, MD 21218 USA

来源：

NATURE COMMUNICATIONS | 2016年 / 7卷

基金：

美国国家科学基金会;

关键词：

STACKING-FAULT ENERGIES; MECHANICAL-PROPERTIES; STRENGTH; CARBIDE; HARDNESS; MAXIMUM;

D O I：

10.1038/ncomms11001

中图分类号：

O [数理科学和化学]; P [天文学、地球科学]; Q [生物科学]; N [自然科学总论];

学科分类号：

07 ; 0710 ; 09 ;

摘要：

The roles of grain boundaries and twin boundaries in mechanical properties are well understood for metals and alloys. However, for covalent solids, their roles in deformation response to applied stress are not established. Here we characterize the nanotwins in boron suboxide (B6O) with twin boundaries along the {0 (1) over bar 11} planes using both scanning transmission electron microscopy and quantum mechanics. Then, we use quantum mechanics to determine the deformation mechanism for perfect and twinned B6O crystals for both pure shear and biaxial shear deformations. Quantum mechanics suggests that amorphous bands nucleate preferentially at the twin boundaries in B6O because the twinned structure has a lower maximum shear strength by 7.5% compared with perfect structure. These results, which are supported by experimental observations of the coordinated existence of nanotwins and amorphous shear bands in B6O, provide a plausible atomistic explanation for the influence of nanotwins on the deformation behaviour of superhard ceramics.

引用

页数：7

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