Phase evolution and magnetic properties of rapidly solidified Si-substituted CoCrFeMnNi high entropy alloy

High entropy alloys (HEAs) have shown good mechanical, electrical, and magnetic properties; thus, they are considered as next-generation structural–functional integration materials. Recent investigations have reported that the “negative mixing enthalpy solid solution” strategy can improve strength–ductility synergy in HEAs {An et al., Nature, 2024, 625(7996)}. However, its effects on magnetic properties remain unknown. Here, CoCrFeNiMn₁₀Si₁₀ HEA (Si10) with high negative mixing enthalpy was fabricated via gas atomization. In this study, the effects of Si substitution and rapid solidification on the magnetic properties of alloy were mainly investigated. Results indicated that most as-atomized Si10 particles exhibited a fine dendritic face-centered cubic phase, whereas a minor body-centered cubic (BCC) phase and a Cr₃Ni₅Si₂-type phase were found in ultrafine particles (less than 5 μm in diameter). Si substitution changed the magnetic transformation from Néel transformation (~50 K) in CoCrFeMnNi (Cantor) alloy to Curie transformation (~70 K) in Si10 alloy. The magnetization of the as-atomized Si10 powder was higher than that of the Cantor alloy and the as-homogenized Si10 powder, particularly at a temperature ranging from Curie temperature to ~800 K. The high magnetization of the as-atomized Si10 powder was primarily due to the presence of a metastable BCC phase and Cr₃Ni₅Si₂-type phase. Moreover, a modified model was proposed to explain the magnetism of multicomponent alloys based on Slater’s equation, which is in accordance with the reported experimental studies.