Nanostructuring of AlSiCrMnFeNiCu High-Entropy Alloy via Cryomilling: Exploring Structural, Magnetic, and Thermoelectric Properties

Abstract

Efforts are made to understand the influence of milling intensity on structure, morphology, magnetic and thermoelectric properties of nonequiatomic nanostructured AlSiCrMnFeNiCu high-entropy alloy (HEA) powders prepared by cryomilling. These powders are cryomilled with different ball-to-powder ratios (BPR) and present a dual-phase structure containing a major B2-type and a minor Cr5Si3-type phase. An increase in BPR enhances the refinement of crystallite size, grain size, and particle size accompanied by a decrease in the phase fraction of the minor Cr5Si3-type phase. Magnetic measurements revealed that at room temperature, sufficient increase in BPR leads to a transition from multi-domain behavior to single-domain behavior which leads to enhancement in soft magnetic properties. Thermal measurements show the presence of different magnetic phase transitions which vary with an increase in BPR. A change of charge carrier type from p to n-type was observed as the grain size is reduced. The figure of merit decreases with the decrease in grain size from 2 × 10–5 for as-cast powders and is lowest for the smallest grain-sized sample due to a decrease in electrical conductivity. This study shows the possibility of exploring nonequiatomic low-density HEAs whose functional properties can be tailored, offering flexibility in material design for specific applications. © 2024 Wiley-VCH GmbH.