Effect of decomposition of the Cr–Fe–Co rich phase of AlCoCrCuFeNi high entropy alloy on magnetic properties

Splat-quenched, as-cast and aged (2 h at 600 °C after casting) AlCoCrCuFeNi high entropy alloys were investigated by means of transmission electron microscopy and three-dimensional atom probe (3D-AP). 3D-AP revealed anti-correlated fluctuations of the Cr and Fe–Co compositions in Cr–Fe–Co-rich regions of the as-cast alloy. The ferromagnetic behavior of AlCoCrCuFeNi high entropy alloy was correlated with the decomposition of the Cr–Fe–Co-rich regions into ferromagnetic Fe–Co-rich and antiferromagnetic Cr-rich domains, the size of which was determined by statistical analysis of 3D-AP data. The splat-quenched alloy showed a softer magnetic behavior as compared to the as-cast and aged alloys. The aged alloy possessed a higher saturation magnetization and coercivity as compared to the as-cast alloy.

Research highlights
► Anti-correlated fluctuations of the Cr and Fe–Co compositions in Cr–Fe–Co-rich regions of the as-cast high entropy (HE) alloy were observed.
► Ferromagnetic behavior was correlated with decomposition in Fe–Co–Cr rich regions.
► Splat-quenched HE alloy shows a soft magnetic behavior.
► Aged HE alloy possessed higher saturation magnetization and coercivity as compared to the as-cast alloy.