Atomistic modeling of capillary-driven grain boundary motion in Cu-Ta alloys

R. K. Koju, K. A. Darling, Kiran Solanki, Y. Mishin

Research output: Contribution to journalArticlepeer-review

20 Scopus citations

Abstract

Nanocrystalline Cu-Ta alloys are emerging as a new class of structural materials preserving the nano-scale grain size up to the melting point of Cu. This extraordinary structural stability is caused by the strong pinning of grain boundaries (GBs) by Ta nano-clusters precipitating from the unstable solid solution after mechanical alloying. Many aspects of the Ta stabilization effect remain elusive and call for further experimental and simulation work. In previous atomistic computer simulations of stress-driven GB migration [JOM 68, 1596 (2016)], the GB–cluster interactions in Cu-Ta alloys have been studied for several different compositions and GB velocities. The results have pointed to the Zener pinning as the main mechanism responsible for the grain stabilization. This paper extends the previous work to the motion of individual GBs driven by capillary forces whose magnitude is similar to that in real nanocrystalline materials. Both the impingement of a moving GB on a set of Ta clusters and the GB unpinning from the clusters are studied as a function of temperature and alloy composition. The results demonstrate a quantitative agreement with the Zener pinning model and confirm the “unzip” mechanism of unpinning found in the previous work. In the random Cu-Ta solid solution, short-circuit Ta diffusion along stationary and moving GBs leads to the nucleation and growth of new GB clusters, which eventually stop the GB motion.

Original languageEnglish (US)
Pages (from-to)311-319
Number of pages9
JournalActa Materialia
Volume148
DOIs
StatePublished - Apr 15 2018

Keywords

  • Atomistic modeling
  • Cluster precipitation
  • Grain boundary
  • Zener pinning

ASJC Scopus subject areas

  • Electronic, Optical and Magnetic Materials
  • Ceramics and Composites
  • Polymers and Plastics
  • Metals and Alloys

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