# Coupling of homogeneous and heterogeneous melting kinetics in polycrystalline materials

## TL;DR

This paper introduces a new model for polycrystalline melting kinetics that couples homogeneous and heterogeneous mechanisms, revealing a critical temperature for mechanism transition and its dependence on grain size.

## Contribution

It presents the first explicit coupling model for melting mechanisms in polycrystalline materials, accounting for grain size effects and mechanism competition.

## Key findings

- Identification of a three-part temperature-time-transformation diagram.
- Critical temperature increases as grain size decreases, following a negative power-law.
- Qualitative agreement with experimental observations.

## Abstract

Melting kinetics of polycrystalline materials is analyzed on the basis of a new model which explicitly couples homogeneous and heterogeneous melting mechanisms. The distinct feature of this approach lies in its ability to evaluate not only grain-size-distribution effects on the overall melting kinetics but also competitions between the two melting mechanisms. For the first time, we reveal the three-part structure of temperature-time-transformation diagrams for melting of polycrystalline materials, through which it is possible to determine a critical temperature across which the dominant melting mechanism switches. The critical temperature increases as the mean-grain-diameter decreases following a negative power-law. The results are qualitatively consistent with experimental observations.