On the core structure and mobility of the $\langle100\rangle \{010\}$ and $\langle100\rangle\{01\overline{1}$}$ dislocations in B2 structure YAg and YCu
Wu Xiao-Zhi(吴小志)†, Wang Shao-Feng(王少峰), and Liu Rui-Ping(刘瑞萍)
Institute for Structure and Function, Chongqing University, Chongqing 400044, China
AbstractDislocations are thought to be the principal mechanism of high ductility of the novel B2 structure intermetallic compounds YAg and YCu. In this paper, the edge dislocation core structures of two primary slip systems $\langle100\rangle${010} and $\langle100\rangle${01$\bar{1}$} for YAg and YCu are presented theoretically within the lattice theory of dislocation. The governing dislocation equation is a nonlinear integro-differential equation and the variational method is applied to solve the equation. Peierls stresses for $\langle100\rangle${010} and $\langle100\rangle${01$\bar{1}$} slip systems are calculated taking into consideration the contribution of the elastic strain energy. The core width and Peierls stress of a typical transition-metal aluminide NiAl is also reported for the purpose of verification and comparison. The Peierls stress of NiAl obtained here is in agreement with numerical results, which verifies the correctness of the results obtained for YAg and YCu. Peierls stresses of the $\langle100\rangle${01$\bar{1}$} slip system are smaller than those of $\langle100\rangle${010} for the same intermetallic compounds originating from the smaller unstable stacking fault energy. The obvious high unstable stacking fault energy of NiAl results in a larger Peierls stress than those of YAg and YCu although they have the same B2 structure. The results show that the core structure and Peierls stress depend monotonically on the unstable stacking fault energy.
Received: 01 August 2008
Revised: 29 October 2008
Accepted manuscript online:
PACS:
61.72.Hh
(Indirect evidence of dislocations and other defects (resistivity, slip, creep, strains, internal friction, EPR, NMR, etc.))
(Stacking faults and other planar or extended defects)
Fund: Project
supported by the National Natural Science Foundation of China (Grant
No 10774196) and by Science Foundation Project of CQ Chongqing
Science \& Technology Commission (CSTC) (Grant No 2006BB4156),
Chongqing University Postgraduates' Science and
Innovation Fund (Grant No 200707A1A0030240).
Cite this article:
Wu Xiao-Zhi(吴小志), Wang Shao-Feng(王少峰), and Liu Rui-Ping(刘瑞萍) On the core structure and mobility of the $\langle100\rangle \{010\}$ and $\langle100\rangle\{01\overline{1}$}$ dislocations in B2 structure YAg and YCu 2009 Chin. Phys. B 18 2905
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