Multiscale modelling of MgO plasticity
Multiscale modelling of MgO plasticity
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DOI：
10.1016/j.actamat.2010.12.020
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发表时间：
2011-04-01
期刊：
影响因子：
9.4
通讯作者：
Cordier, P.
中科院分区：
文献类型：
--
作者：
Amodeo, J.;Carrez, Ph.;Cordier, P.
我们提出了一个纯MgO单晶塑性的多尺度模型。用Peierls-Nabarro-Galerkin方法模拟了速率控制1/2螺旋位错的核心结构< 1 1 0 >。该模型依赖于针对{1 1 0}、{1 0 0}和{1 1 1}平面从头计算的y表面。1/2（1 1 0）螺位错主要分布在{1 1 0}面。在{1 1 0}面和{1 0 0}面滑动时，Peierls摩擦系数分别为15 0 MPa和1.6 GPa。应用扭结对理论来模拟低于非热温度T-a的佩尔斯势垒上位错滑动的热激活，并建立该区域的速度定律。根据Orowan定律，在T-a以下推导出临界分解剪应力。在T-a以上，从离散位错动力学模拟获得非热应力τ（μ），以考虑位错-位错相互作用。这个模型被发现令人满意地再现实验观察到的临界解析剪切应力，提供的贡献的杂质（在实验中不可避免的）被减去。(C)2010 Acta Materialia Inc.由爱思唯尔有限公司出版。保留所有权利。
We propose a multiscale model of plasticity of pure MgO single crystals. The core structure of the rate controlling 1/2 < 1 1 0 > screw dislocations has been modelled by the Peierls Nabarro Galerkin method. This model relies on y-surfaces calculated ab initio for the {1 1 0}, {1 0 0} and {1 1 1} planes. The 1/2 (1 1 0) screw dislocations spread mostly in the {1 1 0} planes. The Peierls friction values are 150 MPa and 1.6 GPa for glide on the {1 1 0} and {1 0 0} planes, respectively. The kink pair theory is applied to model thermal activation of dislocation glide over the Peierls barrier below the athermal temperature T-a and to build a velocity law for this regime. The critical resolved shear stresses are deduced below T-a from the Orowan law. Above T-a the athermal stress tau(mu) is obtained from discrete dislocation dynamics simulations to account for dislocation dislocation interactions. This model is found to satisfactorily reproduce the critical resolved shear stresses observed experimentally, provided the contribution of impurities (unavoidable in experiments) is subtracted. (C) 2010 Acta Materialia Inc. Published by Elsevier Ltd. All rights reserved.