First-principles study of the order-disorder transition in the AlCrTiV high entropy alloy

TL;DR

This study uses first-principles simulations to analyze the temperature-driven order-disorder transition in the AlCrTiV high entropy alloy, providing insights into its thermodynamic and magnetic properties.

Contribution

It presents a detailed first-principles modeling approach to understand the order-disorder transition and magnetic behavior in AlCrTiV alloy, including entropy contributions.

Findings

Transition from B2 to A2 structure with temperature

Presence of compensated ferrimagnetism in structures

Fermi level in a pseudogap

Abstract

The AlCrTiV high entropy alloy undergoes an order-disorder transition from body centered cubic (Strukturbericht A2) at high temperatures to the CsCl structure (B2) at intermediate temperatures. We model this transition using first principles Monte Carlo/molecular dynamics simulations. Simulation results yield the temperature-dependent energy, entropy, heat capacity, occupancy fluctuations, and diffraction patterns. The contribution of chemical disorder to the entropy is calculated on the basis of point and pair cluster frequencies. The simulated structures exhibit compensated ferrimagnetism, and the Fermi level lies in a pseudogap. Sensitivity of structure and magnetism to the exchange-correlation functional is discussed, and neutron diffraction experiments are proposed to help resolve the true chemical order.