Tuning phase-stability and short-range order through Al-doping in (CoCrFeMn)100-xAlx high entropy alloys

TL;DR

This study combines theoretical calculations and experiments to understand how aluminum doping influences phase stability and short-range order in high-entropy alloys, revealing a transition from FCC to BCC structures.

Contribution

It provides a comprehensive analysis of phase evolution and short-range order in Al-doped (CoCrFeMn) alloys using first-principles theory and experimental validation.

Findings

Al-doping induces FCC to BCC phase transition.

Predicted short-range order aligns with experimental data.

Al content controls phase stability and local ordering.

Abstract

For (CoCrFeMn)$_{100-x}$Al$_{x}$ high-entropy alloys, we investigate the phase evolution with increasing Al-content (0 $\le$ x $\le$ 20 at.%). From first-principles theory, the Al-doping drives the alloy structurally from FCC to BCC separated by a narrow two-phase region (FCC+BCC), which is well supported by our experiments. We highlight the effect of Al-doping on the formation enthalpy and electronic structure of (CoCrFeMn)$_{100-x}$Al$_{x}$ alloys. As chemical short-range order (SRO) in multicomponent alloys indicates the nascent local order (and entropy changes), as well as expected low-temperature ordering behavior, we use thermodynamic linear-response within density-functional theory to predict SRO and ordering transformation and temperatures inherent in (CoCrFeMn)$_{100-x}$Al$_{x}$. The predictions agree with our present experimental findings, and other reported ones.