Nucleation of amorphous shear bands at nanotwins in boron suboxide.,Nature Communications

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Nucleation of amorphous shear bands at nanotwins in boron suboxide.
Nature Communications ( IF 14.7 ) Pub Date : 2016-Mar-22 , DOI: 10.1038/ncomms11001
Qi An ₁ , K Madhav Reddy _{2,

3} , Jin Qian ₁ , Kevin J Hemker ₃ , Ming-Wei Chen ₂ , William A Goddard ₁

Affiliation

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 {0111} 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.

中文翻译：

亚氧化硼中纳米孪晶处无定形剪切带的成核。

对于金属和合金，晶界和孪晶界在机械性能中的作用是众所周知的。但是，对于共价固体，尚未确定它们在对施加应力的变形响应中的作用。在这里，我们使用扫描透射电子显微镜和量子力学，表征了沿{0111}平面具有双边界的低氧化硼（B6O）中的纳米孪晶。然后，我们使用量子力学来确定完美的和孪生的B6O晶体的纯剪切变形和双轴剪切变形的变形机理。量子力学表明，非晶态带优先在B6O的孪晶边界处成核，因为孪晶结构的最大剪切强度比理想结构低7.5％。这些结果，

更新日期：2016-04-01

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