Creep Behavior Study for Ultra-Fine Grained Nano-Crystalline Metallic Systems Using Atomistic Simulation

Abstract

Molecular dynamics (MD) simulation based study of creep behaviour nano crystalline metal and nano joint between two different nano-crystalline metal have been performed. Simulation of creep behaviour of nano crystalline metal is performed taking nano crystalline Nickel as a representative system. On the other hand, creep behaviour of nano joint between two different nano-crystalline metallic systems is investigated taking nano joint of nano-crystalline (NC) Ni and Fe-Ni-Cr alloy (18 at% Cr, 8 at% Ni and rest Fe) as representative case. MD simulation has been carried out using EAM (Embedded Atomic Method) potential. Centro-symmetry parameter (CSP) analysis, common neighbour analysis (CNA), radial distribution function (RDF), Wigner-Seitz defect analysis and Voronoi cluster analysis (VCs) have been performed to study structural evolution during creep process. The MD study reveals that the grain boundary diffusion is the governing mechanism of creep deformation in ultra-fine grained (< 10 nm) nano crystalline metallic systems. In case nano joint between two nano metallic systems, the atoms are observed to be displaced more which are nearer to the interface during creep.