Unravelling densification during sintering by multiscale modelling of grain motion

TL;DR

This paper develops a multiscale model combining molecular dynamics and phase-field methods to accurately simulate grain motion during sintering, addressing previous limitations and capturing microstructural evolution.

Contribution

It introduces a novel phase-field model for sintering based on molecular dynamics insights, enabling realistic simulation of grain motion and microstructure development.

Findings

Model reproduces sintering rate dependence on particle size

Superposition principle for grain displacement during vacancy absorption

Model is valid for systems with 97 to 262 particles

Abstract

The resulting microstructure after the sintering process determines many materials properties of interest. In order to understand the microstructural evolution, simulations are often employed. One such simulation method is the phase-field method, which has garnered much interest in recent decades. However, the method lacks a complete model for sintering, as previous works could show unphysical effects and the inability to reach representative volume elements. Thus the present paper aims to close this gap by employing molecular dynamics and determining rules of motion which can be translated to a phase-field model. The key realization is that vacancy absorption induced motion of grains travels through a grain structure without resistance. Hence the total displacement field of a green body is simply the superposition of all grains reacting in isolation to local vacancy absorption events. The resulting phase-field model is shown to be representative starting from particle counts between 97 and 262 and contains the qualitative correct dependence of sintering rate on particle size.