A Novel Soft‐Magnetic B2‐Based Multiprincipal‐Element Alloy with a Uniform Distribution of Coherent Body‐Centered‐Cubic Nanoprecipitates

Multiprincipal-element alloys (MPEAs), including high-entropy alloys, are a new class of materials whose thermodynamical properties are mainly driven by configuration entropy, rather than enthalpy in the traditional alloys, especially at high temperatures. Herein, the design of a novel soft-magnetic nonequiatomic, quaternary MPEA is described, via tuning its chemical composition to deliberately manipulate its microstructure, such that it contains ultrafine ferromagnetic body-centered-cubic (BCC) coherent nanoprecipitates (3-7 nm) uniformly distributed in a B2-phase matrix. The new alloy Al_1.5 Co₄ Fe₂ Cr exhibits high saturation magnetization (M_S = 135.3 emu g^-1 ), low coercivity (H_C = 127.3 A m^-1 ), high Curie temperature (T_C = 1061 K), and high electrical resistivity (ρ = 244 μΩ cm), promising for soft magnets. More importantly, these prominent soft-magnetic properties are observed to be retained even after the alloy is thermally exposed at 873 K for 555 h, apparently attributable to the excellent stability of the coherent microstructure. The versatility of the magnetic properties of this new alloy is discussed in light of the microstructural change induced by tuning the chemical composition, and the enhanced performance of the alloy is compared directly with that of the traditional soft-magnetic alloys. The perspective is also addressed to design high-performance soft-magnetic alloys for high-temperature applications.