Atomistic mechanisms of fatigue in nanotwinned metals

被引：51

作者：

Zhou, Xiaoling ^{[1
]}

Li, Xiaoyan ^{[1
,2
]}

Chen, Changqing ^{[1
,3
]}

机构：

[1] Tsinghua Univ, Dept Engn Mech, Appl Mech Lab, Beijing 100084, Peoples R China

[2] Tsinghua Univ, Ctr Adv Mech & Mat, Beijing 100084, Peoples R China

[3] Tsinghua Univ, CNMM, Beijing 100084, Peoples R China

来源：

ACTA MATERIALIA | 2015年 / 99卷

基金：

中国国家自然科学基金;

关键词：

Fatigue crack; Nanoscale twins; Dislocation; Detwinning; Atomistic simulation; ULTRAHIGH-STRENGTH; MAXIMUM STRENGTH; DEFORMATION; ALUMINUM;

D O I：

10.1016/j.actamat.2015.07.045

中图分类号：

T [工业技术];

学科分类号：

08 ;

摘要：

We investigate the fatigue behavior of nanotwinned Cu using a combination of molecular statics and molecular dynamics simulations. The presence of nanoscale twins is found to enhance fatigue crack growth resistance. For the twin-free nanocrystalline samples, the fatigue crack propagates by linking the nanovoids that are formed ahead of the crack tip. In the case of the nanotwinned samples, however, it advances as the crack tip alternately blunts and re-sharpens due to dislocation emission and slip. Both detwinning and crack closure are observed in the path of the fatigue crack in nanotwinned samples with a high density of twin boundaries. As the twin number per grain (quantified by the ratio of the mean grain size to the twin boundary spacing d/lambda) increases, detwinning increases the dissipated energy of fatigue cracking, leading to enhanced fatigue resistance. The atomistic simulations show that fatigue crack growth in nanotwinned Cu conforms to Paris' law. In conjunction with the experimental results, we obtain a quantitative estimation of the Paris' law exponent (similar to 4.0), which is in agreement with the theoretical predictions from the damage accumulation model. (C) 2015 Acta Materialia Inc. Published by Elsevier Ltd. All rights reserved.

引用

页码：77 / 86

页数：10

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