Phase-field study for the splitting mechanism of coherent misfitting precipitates in anisotropic elastic media

TL;DR

This paper uses phase-field modeling to investigate how elastic anisotropy and diffusion cause splitting of coherent misfitting precipitates, revealing interface instability as the key mechanism.

Contribution

It introduces a phase-field approach to elucidate the elastic anisotropy-driven splitting mechanism of coherent precipitates, aligning well with experimental observations.

Findings

Splitting is triggered by interface grooving due to elastic anisotropy.

The morphological evolution matches experimental patterns.

Elastic anisotropy and diffusion jointly induce precipitate splitting.

Abstract

Coherent misfitting precipitates in elastically stressed media such as $\gamma \prime$ particles in nickel-based super-alloys show various splitting patterns such as doublets, quartets, or octets due to their misfit strain energy. While it is an interesting instability phenomenon defying conventional surface thermodynamics, its mechanism is not completely clear. Through a phase-field study upon the splitting behavior and morphological evolution of coherent precipitates, we show that an interface instability driven by elastic anisotropy and a diffusion field can generate elastically induced splitting during diffusional phase transition. Particle splitting is triggered by interface grooving which advances by penetrating grooves into the interior of the particle. The sequential evolution of shapes during the splitting process is in good agreement with previous experiments.