Thermodynamic properties of CrMnFeCoNi high entropy alloy at elevated electronic temperatures

TL;DR

This paper investigates the electronic thermodynamic properties of the CrMnFeCoNi high-entropy alloy at elevated temperatures, revealing nonthermal melting effects under ultrafast laser irradiation, crucial for modeling its laser ablation behavior.

Contribution

It introduces a combined computational approach to evaluate electronic heat capacity, thermal conductivity, and electron-phonon coupling at high temperatures for the alloy, highlighting nonthermal melting phenomena.

Findings

Electronic properties are significantly altered at ~24,000 K.

Nonthermal melting occurs without atomic temperature increase.

Damage threshold fluence varies across photon energies.

Abstract

The Cantor alloy (equiatomic CrMnFeCoNi) is a high-entropy alloy with unique physical properties and radiation resistance. To model its response to intense laser pulses, the parameters of the electronic ensemble are required. In this work, the electronic heat capacity, thermal conductivity, and electron-phonon coupling strength at elevated electronic temperatures are evaluated using a combined approach that incorporates tight-binding molecular dynamics and the Boltzmann equation. The damage threshold fluence is estimated for a wide range of photon energies, from XUV to hard X-rays. It is found that at the electronic temperatures ~24,000 K (absorbed dose ~6 eV/atom), the Cantor alloy experiences nonthermal melting due to modification of the interatomic potential induced by electronic excitation, even without the increase of the atomic temperature. This effect must be included in reliable models of CrMnFeCoNi ablation under ultrafast laser irradiation.