Molecular Dynamics Study on the Characteristics of Edge and Screw Dislocations in Gamma/Gamma-Prime Microstructure of Ni-Based Superalloy

Abstract

Fundamental characteristics of edge and screw dislocations in the y/y′ microstructure of Ni-based superalloys are investigated by using molecular dynamics simulations. Edge/screw dislocations are nucleated and glide in a slab cell of the Ni matrix involving an apex of a cuboidal Ni3Al precipitate, that mimics a part of the idealized y/y′ microstructure. The edge dislocation decreases its velocity at the y′ precipitate, showing dislocation pinning there, then penetrates it under the force from following dislocations. The screw dislocation runs through the precipitate without slowdown by shrinking the width between its Shockley partials. Detailed investigation of the stress distribution suggests that the constriction is due to interactions between the stress field around the precipitate and the partials: the stress causes a repulsive Peach-Koehler force on the leading partial and an attractive force on the trailing one since their edge components have opposite Burgers vectors.KeywordsMolecular DynamicsEdge and Screw Dislocationy/y′ MicrostructureNi-Based SuperalloyEmbedded Atom Method