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.