Materials Transactions Online

Materials Transactions, Vol.53 No.01 (2012) pp.156-160
© 2012 The Japan Institute of Metals

Grain Size Dependence of Creep in Nanocrystalline Copper by Molecular Dynamics

Yun-Jiang Wang, Akio Ishii and Shigenobu Ogata

Department of Mechanical Science and Bioengineering, Graduate School of Engineering Science, Osaka University, Osaka 560-8531, Japan

The grain size dependence of creep is critical to understand the plastic deformation mechanism of nanoscale metals. Here we used molecular dynamics to study the stress-induced grain size exponent transition in creep of nanocrystalline copper. The grain size exponent was found to initially increase with increasing stress, then decrease after some critical stress. The derived grain size exponents are in agreement with experimental results for diffusional and grain boundary sliding creep at low stress. While, the founded decreasing grain size exponent with increasing stress for dislocation nucleation creep in nanocrystal is in contrast with conventional materials. We propose a constitutive equation for dislocation nucleation governed creep in nanocrystal to explain its grain size dependence transition with stress.

(Received 2011/07/29; Accepted 2011/09/05; Published 2011/12/25)

Keywords: creep, nanocrystal, grain size dependence, molecular dynamics

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