Role of crystal defects on brittleness of C15 Cr2Nb Laves phase

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	Role of crystal defects on brittleness of C15 Cr2Nb Laves phase
	Z. Q. Yang; M. F. Chisholm; B. Yang; X. L. Ma; Y. J. Wang; M. J. Zhuo; S. J. Pennycook
	2012
发表期刊	Acta Materialia
ISSN	1359-6454
卷号	60 期号:6-7 页码:2637-2646
摘要	First-principles calculations, high-resolution transmission electron microscopy (HRTEM) investigations and geometrical phase analysis of lattice strain based on HRTEM images have been carried out on C15 Cr2Nb Laves phase. Asymmetrical nanoscale regions with severe lattice distortion were observed in the vicinity of Shockley partial dislocation cores. These disturbed regions are the result of synchroshear inside the Nb-Cr-Nb triple layers. Reactions of dislocations with twin boundaries (TBs) also result in severe lattice distortion. The resulting local lattice distortion and perturbed strain field deleteriously impact dislocation-governed plasticity. First-principles calculations show that cleavage occurs preferentially between the single Cr layer and the Nb-Cr-Nb triple layer in these materials. TBs, which are on single Cr layers, nucleate and propagate cracks readily in Cr2Nb, as evidenced by the lattice dilatation along a TB interacting with one 60 degrees dislocation. The present study shows atomic level evidence on how crystal defects and their interactions influence the mechanical properties, especially the poor toughness at low temperatures, of C15 Cr2Nb. This provides new insights into the origin of low temperature brittleness of Laves compounds with complex structures. (C) 2012 Acta Materialia Inc. Published by Elsevier Ltd. All rights reserved.
部门归属	[yang, z. q.; yang, b.; ma, x. l.; wang, y. j.; zhuo, m. j.] chinese acad sci, inst met res, shenyang natl lab mat sci, shenyang 110016, peoples r china. [yang, z. q.; chisholm, m. f.; pennycook, s. j.] oak ridge natl lab, div mat sci & technol, oak ridge, tn 37831 usa.;yang, zq (reprint author), chinese acad sci, inst met res, shenyang natl lab mat sci, shenyang 110016, peoples r china.;yangzq34@yahoo.com
关键词	Laves Phase Dislocation Twin Boundary Fracture Brittleness Resolution Electron-microscopy Density-functional Theory Single-crystals Deformation Microstructures Intermetallic Compounds Mechanical-behavior High-temperatures 1st-principles Fracture Nbcr2
URL	查看原文
文献类型	期刊论文
条目标识符	http://ir.imr.ac.cn/handle/321006/60409
专题	中国科学院金属研究所
推荐引用方式 GB/T 7714	Z. Q. Yang,M. F. Chisholm,B. Yang,et al. Role of crystal defects on brittleness of C15 Cr2Nb Laves phase[J]. Acta Materialia,2012,60(6-7):2637-2646.
APA	Z. Q. Yang.,M. F. Chisholm.,B. Yang.,X. L. Ma.,Y. J. Wang.,...&S. J. Pennycook.(2012).Role of crystal defects on brittleness of C15 Cr2Nb Laves phase.Acta Materialia,60(6-7),2637-2646.
MLA	Z. Q. Yang,et al."Role of crystal defects on brittleness of C15 Cr2Nb Laves phase".Acta Materialia 60.6-7(2012):2637-2646.