Creep Behavior Study of Join of Nano Crystalline Stainless Steel and Nanocrystalline Nickel Using Molecular Dynamics Simulation

Abstract

Creep properties of a join between fine grained (grain size ~ 6 nm) nano crystalline (NC) dissimilar materials such as 304 stainless steel and Ni is studied using molecular dynamics (MD) simulation for a constant stress 1 GPa and different temperatures (e.g. 1209K ,1309K, and 1409 K) using embedded atom method (EAM) potential. This join between two dissimilar nano-crystalline materials is prepared by heating the interfacial region to 500K and hold at that temperature for 50 ps, then cooled to room temperature (i.e. 300K). Uniaxial tensile creep simulation has been carried out up till 200ps. All the simulated creep curves have extensive and significant tertiary creep regime but primary creep and steady state creep deformation are very short. Mean square displacement (MSD) is also determined for different temperatures (e.g. 1209K, 1309K, and 1409 K) for estimating diffusivity. This MD simulation work shows that the creep deformation of the join of NC materials is significantly governed by atomic diffusion. Diffusivity of Nickel is observed to be more compared to iron and Chromium. The joined sample becomes amorphous at the end stage of tertiary regime of creep deformation.