Experimental observations of amorphization in stoichiometric and boron-rich boron carbide
Experimental observations of amorphization in stoichiometric and boron-rich boron carbide
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DOI：
10.1016/j.actamat.2019.09.052
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发表时间：
2019-12-01
期刊：
影响因子：
9.4
通讯作者：
Hemker, Kevin J.
中科院分区：
文献类型：
--
作者：
Chauhan, Ankur;Schaefer, Mark C.;Hemker, Kevin J.
碳化硼非常硬，但已经显示出当受到大的非流体静力应力时会发生应力诱导的非晶化。这种局部非晶化与其剪切强度的突然损失和不良的弹道性能有关。最近的量子力学预测表明，硼富集可用于减轻碳化硼中的非晶化。作为检验这一假设的手段，研究了化学计量的碳化硼（名义上为B4C）和富B的碳化硼（名义上为B6.3C）的新组合物。纳米压痕后的拉曼光谱显示，在拉曼峰与非晶化的富B材料中的明显减少。透射电子显微镜观察nanoindents下面的区域促进直接观察非晶化，证实了拉曼发现，非晶化减少在富B标本，并提供了额外的洞察变形机制。据推测，富硼合金提供了一种途径，以减少局部非晶化的碳化硼。(C)2019 Acta Materialia Inc.由爱思唯尔有限公司出版。保留所有权利。
Boron carbide is extremely hard but has been shown to undergo stress-induced amorphization when subjected to large nonhydrostatic stresses. This localized amorphization has been associated with the sudden loss of its shear strength and poor ballistic performance. Recent quantum mechanics predictions suggest that boron-enrichment may be used to mitigate amorphization in boron carbide. As a means to test this hypothesis, stoichiometric boron carbide (nominally B4C) and a novel composition of B-rich boron carbide (nominally B6.3C) were investigated. Nanoindentation followed by Raman spectroscopy revealed an obvious reduction in the Raman peaks associated with amorphization in the B-rich material. Transmission electron microscopy observations of the region below the nanoindents facilitated direct observation of amorphization, confirmed the Raman finding that amorphization is reduced in the B-rich specimens, and provided additional insight into deformation mechanisms. It is surmised that boron-rich alloys offer a path to reducing local amorphization in boron carbide. (C) 2019 Acta Materialia Inc. Published by Elsevier Ltd. All rights reserved.