Effect of Zr addition on creep properties of ultra-fine grained nanocrystalline Ni studied by molecular dynamics simulations

Abstract

Molecular dynamics (MD) simulation has been carried out using embedded atom method potential to assay the variation of creep behaviour of nanocrystalline (NC) Ni and Ni–Zr alloy (Zr addition of 3at.%, 6at.% and 12at.%) having grain size ∼6nm due to the Zr addition. In this study, the creep process is evaluated at constant temperature of 1209K and constant applied load of 1.0GPa with Zr additions both randomly distributed in the NC Ni sample and segregated at the grain boundaries. Centro-symmetry parameter analysis, radial distribution function evolution, Wigner-Seitz defect analysis and Voronoi cluster analysis have been performed to provide the insight of underlying mechanism for accounting the deviation in creep properties owing to Zr addition in NC Ni. In this work the underlying mechanism based on structure property correlation is evaluated for accounting the improved creep properties of NC Ni-Zr alloy having segregated Zr atoms at grain boundaries compared to that of NC Ni and Ni–Zr alloy containing randomly distributed Zr atoms.