Twin nucleation mechanisms at a crack tip in an hcp material: Molecular simulation

被引：49

作者：

Kucherov, L. ^{[1
]}

Tadmor, E. B. ^{[1
]}

机构：

[1] Technion Israel Inst Technol, Dept Mech Engn, IL-32000 Haifa, Israel

来源：

ACTA MATERIALIA | 2007年 / 55卷 / 06期

关键词：

twinning; fracture; dislocations; nucleation of phase transformations; molecular dynamics;

D O I：

10.1016/j.actamat.2006.10.056

中图分类号：

T [工业技术];

学科分类号：

08 ;

摘要：

Twinning is an important deformation mode in hexagonal close-packed (hcp) materials that can strongly affect fracture toughness. In order to clarify the early stages of twin nucleation, lattice statics simulations of zirconium crystals containing mixed-mode basal cracks with [(1) over bar2 (1) over bar0] and [1 (1) over bar 00] front orientations were carried out using an embedded-atom method potential. The simulations show that crack tip twin nucleation is a two-stage process: (I) initial plastic deformation occurs within a thin layer ahead of the crack, possibly involving basal slip, crack tip blunting by the formation of Frank partials or an hcp-face-centered cubic (fcc) transformation produced by Shockley partials emitted from the crack tip and (II) a twin forms in the surrounding hcp matrix. In this second stage, either a {11 (2) over bar1} twin is nucleated homogeneously or a {10 (1) over bar1} twin is nucleated heterogeneously by Shockley partials that nucleate inside the fec region and penetrate the hcp matrix. (c) 2007 Acta Materialia Inc. Published by Elsevier Ltd. All rights reserved.

引用

页码：2065 / 2074

页数：10