Modeling grain size dependent optimal twin spacing for achieving ultimate high strength and related high ductility in nanotwinned metals
Modeling grain size dependent optimal twin spacing for achieving ultimate high strength and related high ductility in nanotwinned metals
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DOI：
10.1016/j.actamat.2011.05.027
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发表时间：
2011-08-01
期刊：
影响因子：
9.4
通讯作者：
Lu, Jian
中科院分区：
文献类型：
--
作者：
Zhu, Linli;Ruan, Haihui;Lu, Jian
为了研究纳米孪晶间距对材料强度、延展性和加工硬化率的影响，建立了纳米孪晶金属的塑性模型。特别是，在孪晶和晶界附近的位错堆积区以及孪晶部分位错在强化和加工硬化中的独特作用被纳入模型。在评估纳米孪晶金属的拉伸延展性时，考虑了与孪晶片和/或晶界相关的不同局部破坏机制之间的竞争。本研究提供了一个定量连续塑性模型，能够描述纳米孪晶金属的强度、延展性和加工硬化率随孪晶间距的变化。对于晶粒尺寸为500 nm的纳米孪晶铜，该模型预测最大强度的临界孪晶间距为13 nm，与实验观察结果非常吻合。发现临界孪晶间距与晶粒尺寸成线性关系，这与最近的分子动力学模拟结果一致。(C) 2011材料学报Elsevier Ltd.出版。版权所有。
We have developed a mechanism-based plasticity model of nanotwinned metals to investigate the effect of twin spacing on strength, ductility and work hardening rate of such materials. In particular, the unique roles of dislocation pile-up zones near twin and grain boundaries, as well as twinning partial dislocations, in strengthening and work hardening are incorporated in the model. Competition between different local failure mechanisms associated with twin lamellae and/or grain boundaries is considered in evaluating the tensile ductility of nanotwinned metals. The present study provides a quantitative continuum plasticity model capable of describing the variations in strength, ductility and work hardening rate of nanotwinned metals with the twin spacing. For nanotwinned copper a grain size of 500 nm, the model predicts a critical twin spacing for the maximum strength at 13 nm, in excellent agreement with experimental observations. The critical twin spacing is found to be linearly proportional to the grain size, which is consistent with recent molecular dynamics simulations. (C) 2011 Acta Materialia Inc. Published by Elsevier Ltd. All rights reserved.