Effects of coherency stress and vacancy sources/sinks on interdiffusion across coherent multilayer interfaces - Part II: Interface sharpening and intermixing rate

Haibo Wan, Yao Shen, Xuejun Jin, Youxing Chen, Jian Sun

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6 Scopus citations

Abstract

Vacancy-mediated interdiffusion in coherent Mo/V and Cu/Ni multilayers is simulated to evaluate the effects of coherency stress and vacancy sources/sinks on interface sharpening and the intermixing rate, using the phase field model developed in a previous paper for two limiting cases: ideal vacancy sources/sinks densely distributed or not present at all. Interface sharpening stems from a large diffusion coefficient asymmetry across the interface, which in turn originates from the large difference in vacancy formation and migration energies between the two constituent layers. Remarkable sharpening is found in Mo/V multilayers either with dense or without vacancy sources/sinks, but only in Cu/Ni with a high density of sources/sinks. Sharpening is suppressed by coherency stress in Cu/Ni regardless of the existence of vacancy sources/sinks, but only promoted in Mo/V with a high density of sources/sinks. The intermixing rate is suppressed in Mo/V by the introduction of a high density of vacancy sources/sinks that are parallel or perpendicular to the interfaces, or uniformly distributed in all orientations, but only promoted in Cu/Ni by the introduction of vacancy sources/sinks that are parallel to the interfaces. The intermixing rate is promoted in Mo/V by coherency stress regardless of the existence of vacancy sources/sinks, but promoted in Cu/Ni by coherency stress only when the vacancy sources/sinks are parallel to the interface or not present at all. The effects of that part of coherency stress induced by the mismatch in atomic volumes on interface sharpening and the intermixing rate are opposite to, but dominant over, those of the stress induced by lattice creation/annihilation in vacancy sources/sinks.

Original languageEnglish (US)
Pages (from-to)2539-2553
Number of pages15
JournalActa Materialia
Volume60
Issue number6-7
DOIs
StatePublished - Apr 2012

Bibliographical note

Funding Information:
This research was supported by the National Science Foundation of China under Project Nos. 50971090, 50601018 and 50890174. Critical comments and helpful discussions with Dr. J. Svoboda are gratefully acknowledged. Helpful discussions with Dr. Jian Wang and Profs. Yunzhi Wang, Max Lagally, and Hanchen Huang are also acknowledged. The authors are also grateful to Dr. Jian Wang for a critical review of the manuscript. The authors thank the reviewer for critical comments.

Copyright:
Copyright 2012 Elsevier B.V., All rights reserved.

Keywords

  • Coherency stress
  • Interface sharpening
  • Multilayers
  • Substitutional diffusion
  • Vacancies

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