Interstitialcy-based reordering kinetics of Ni$_3$Al precipitates in irradiated Ni-based super alloys

TL;DR

This study investigates how self-interstitial atoms promote reordering in Ni3Al precipitates within irradiated Ni-based superalloys, using atomistic simulations and a mean-field model to understand the kinetics at various temperatures.

Contribution

It introduces a mean-field rate theory model for interstitialcy-based reordering, validated by atomistic simulations, revealing reordering mechanisms at low temperatures.

Findings

Self-interstitial atoms act as reordering agents in Ni3Al.

The model predicts reordering at temperatures as low as 500 K.

Simulation data supports the proposed reordering mechanism.

Abstract

Neutron irradiation tends to promote disorder in ordered alloys through the action of the thermal spikes that it generates, while simultaneously introducing point defects and defect clusters. As they migrate, these point defects will promote reordering of the alloys, acting against irradiation-induced disordering. In this study, classical molecular dynamics and a highly parallel accelerated sampling method are used to study the reordering kinetics of Ni$_3$Al under the diffusion of self-interstitial atoms (SIA). By monitoring the order parameter and potential energy from atomistic simulations, we show that the SIA acts as a reordering agent in Ni$_3$Al. A mean-field rate theory model of the interstitialcy-based reordering kinetics is introduced, which reproduces simulation data and predicts reordering at temperatures as low as 500 K.