Effect of nanovoid on grain boundary migration and disclinated cracking in nanocrystalline materials

INTERNATIONAL JOURNAL OF SOLIDS AND STRUCTURES

卷:155

Article

Li, Qifeng¹  Zhao, Yingxin^1,2  Xu, Lianyong² 

[1] Tianjin Univ Technol, Sch Mat Sci & Engn, Tianjin 300384, Peoples R China

[2] Tianjin Univ, Sch Mat Sci & Engn, Tianjin 300072, Peoples R China

关键词: Nanovoid induced stresses;    Grain boundary migration;    Disclinated cracking;    Analytical solution;    Critical condition;   

DOI  :  10.1016/j.ijsolstr.2018.07.016

来源: Elsevier

【 摘 要 】

The greatest objective in the design of nanocrystalline materials (NCMs) is to improve their strength while maintain ductility. Therefore, from both fundamental and applied viewpoints, to reveal the causes of the improved damage tolerance of NCMs, there is large interest in the advancement of an understanding of the fundamental micromechanisms for the competition/interaction between plastic deformation and fracture process in NCMs. In doing so, this paper develops a theoretical model to describe the energy and critical conditions of the tilt GB migration and then the disclinated TJ nanocrack nucleation and growth processes near a nanovoid at the triple junctions (TJs) of GBs in plastically deformed NCM. The analytic solutions of the total energy changes that characterize these processes are derived quantitatively by the complex variable method. The results show that the stress-driven tilt GB migration near a nanovoid is energetically favorable and effective in relieving high local stresses near a nanovoid, which is crucially significant for stopping further nanovoid growth and enhancing the ductility of the plastically deformed NCMs. On the other hand, GB disclination storage is capable of causing the stress concentration, and consequent generation and growth of nanocracks at the TJs near a nanovoid, thereby decreasing their ductility. The predominant mechanism controlling plasticity deformation and fracture process in NCMs is closely related with nanovoid, GB configuration and geometry. (C) 2018 Published by Elsevier Ltd.

【 授权许可】

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