Grain boundary migration and Zener pinning in a nanocrystalline Cu-Ag alloy
RJ Li and J Zhou and Y Li and YH Liu and BB Zhao and FZ Ren, MODELLING AND SIMULATION IN MATERIALS SCIENCE AND ENGINEERING, 28, 065017 (2020).
Grain boundary (GB) migration and Zener pinning, i.e. retardment of migrating GBs by second-phase particles, in a nanocrystalline Cu-Ag alloy have been investigated via molecular dynamics simulation. Among 86 GBs of different rotation axes and misorientation angles, about half of the GBs either did not move for an obvious distance within limited simulation time or underwent unsteady migration, and the other GBs exhibited steady migration. For the motionless and unsteady-migration GBs, boundary faceting was frequently observed. In particular, as found in experiments, all low angle GBs and several high angle GBs became faceted. For the steady-migration GBs, rotation-axis and misorientation dependences of GB energy, GB mobility and particle pinning effects have been systematically revealed. It is found that both the energy and mobility of low angle GBs were generally lower than those of high angle GBs, GBs of distinct rotation axes differed in mobility by as large as three orders of magnitude, and the maximum pinning force always agreed well with the theoretical prediction proposed by Ashbyet al1. Moreover, pinning efficiency obtained via comparisons between boundary migration with and without the pinning indicates that the efficiency is not related to the GB mobility or the maximum pinning force and a nanosized second phase particle seems to have a limited effect on retarding GB motion in very fine nanograins.
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