# Atomic-Scale Interfacial Dynamics and Twin Formation in Cu/Al2Cu/Al Layered Composites During Cooling: Insights from Molecular Dynamics Simulations

## TL;DR

This study uses simulations to explore how cooling affects the structure and properties of a Cu/Al2Cu/Al composite material at the atomic level.

## Contribution

The study provides new insights into atomic-scale interfacial dynamics and twin formation during cooling in Cu/Al2Cu/Al composites.

## Key findings

- Cu atoms show limited diffusion near the Cu/Al2Cu interface, while Al atoms diffuse in all directions at the Al/Al2Cu interface.
- A twin crystal forms due to symmetrical lattice distribution during Al2Cu growth towards the Al side.
- Cooling to 650 K initiates 1/6<112> Shockley incomplete dislocations in the Al layer.

## Abstract

This study investigates the cooling process of the Cu/Al2Cu/Al system following high-temperature diffusion using molecular dynamics (MD) simulations based on an embedded atom method potential. The analysis focused on various characteristics to determine the structural and property changes within the Cu/Al2Cu/Al system during cooling. The findings reveal that only a small number of Cu atoms diffused along the Z-axis near the Cu/Al2Cu interface, while significant diffusion of Al atoms occurs in all directions at the Al/Al2Cu interface. Moreover, 673 K is identified as a crucial temperature for the crystal transformation of the Cu/Al2Cu/Al system during cooling. The Cu/Al2Cu interface exhibited migration behavior along the positive Z-axis. Additionally, the growth of Al2Cu towards the Al side resulted in a symmetrical lattice distribution along the Al/Al2Cu interface, leading to the formation of a twin crystal. In the AI layer, locally disordered atoms transform into vacancies under stress, accumulating as the temperature drops, thereby providing favorable conditions for dislocation initiation. Notably, cooling of the Al layer to 650 K led to the initial generation of 1/6<112> Shockley incomplete dislocations.