Achieving strength–ductility trade-off of brittle soft magnetic multi-principal element alloy via metastability engineering.

This article focuses on the development of a soft magnetic multi-principal element alloy (SMMPEA), specifically Fe37Co36Ni15Al6Ti3Ta3, that achieves a balance between high mechanical strength, ductility, and soft magnetic properties through a metastability engineering strategy utilizing transformation-induced plasticity (TRIP). The alloy exhibits a tensile strength of 1.65 GPa, 15% elongation, saturation magnetization of 131 emu/g, and low coercivity of 12.5 Oe, attributed to the elimination of large non-magnetic body-centered cubic (BCC) phases and the presence of nanoscale L12 precipitates within a face-centered cubic (FCC) matrix. During deformation, a stress-induced FCC-to-BCC phase transformation enhances plasticity and work hardening without significantly increasing coercivity due to the semi-coherent FCC–BCC interfaces and precipitate sizes smaller than the magnetic domain wall width. This work demonstrates that the TRIP mechanism can effectively improve the strength–ductility synergy in SMMPEAs while maintaining desirable soft magnetic characteristics, offering a promising approach for high-performance magnetic components.