Laser Ablation of Al-Ni Alloys and Al-Ni Layer Systems simulated with Molecular Dynamics and the Two-Temperature Model

TL;DR

This study uses molecular dynamics combined with a two-temperature model to simulate laser ablation of Al-Ni alloys and layered systems, revealing different ablation mechanisms and alloying effects depending on laser fluence and film thickness.

Contribution

It introduces a modified MD simulation approach for inhomogeneous layered systems and provides insights into ablation mechanisms and alloying behavior under laser irradiation.

Findings

Ablation occurs as a whole for 8 nm Al films but only partially for 24 nm films.

High fluences induce a transition from phase explosion to vaporization in Al-Ni compounds.

Below threshold, alloying with a gradient is observed in thin layered systems.

Abstract

Laser ablation of Al-Ni alloys and Al films on Ni substrates has been studied by molecular dynamics simulations (MD). The MD method was combined with a two-temperature model to describe the interaction between the laser beam, the electrons and the atoms. The challenge for alloys and mixtures is to find the electronic parameters: electron heat conductivity, electron heat capacity and electron-phonon coupling parameter. The challenge for layered systems is to run simulations of an inhomogeneous system which requires modification of the simulation code. Ablation and laser-induced melting was studied for several Al-Ni compounds. At low fluences above the threshold ordinary ablation behavior occurred while at high fluences the ablation mechanism changed in Al$_3$Ni and AlNi$_3$ from phase explosion to vaporization. Al films of various thicknesses on a Ni substrate have also been simulated. Above threshold, 8 nm Al films are ablated as a whole while 24 nm Al films are only partially removed. Below threshold, alloying with a mixture gradient has been observed in the thin layer system.