Microstructure and magnetic behaviors of FeCoNi (Al) alloys with incoherent nanoprecipitates prepared by high-pressure solidification

In this work, we investigated the microstructure and magnetic properties of FeCoNi (Al) high-entropy alloys (HEAs) prepared by high-pressure solidification (HPS). The results show that incoherent nanoprecipitates distributed in uniaxial grain uniformly, which significantly reduces the average magnetic anisotropy of the alloys. The maximum permeability (μm) of alloys increased prominently (i.e. from 47800 to 169000 in FeCoNi alloy and 78000–205000 in FeCoNiAl alloy) and the intrinsic coercivity decreased by 43% in FeCoNiAl alloy after HPS. Nanoprecipitates were related with the double sluggish diffusion effect (DSDE), which is caused by the coupling of high-entropy and high-pressure during solidification process. DSDE not only ensures the retention of short-range ordering (SRO) structures in the liquid metal, but also inhibits the SRO structures’ growth during the solidification process. These SRO structures provide structural conditions to the nanoprecipitates. The molecular dynamics simulation results provide support to the crucial role of DSDE on short-range ordering structures. HPS can effectively reduce the volume fraction of grain boundary precipitates also due to DSDE. Thus, DSDE exhibited the great significance to understand the microstructure of FeCoNi (Al) HEAs by HPS. The perspective also provides a paradigm to enhance the magnetic property of soft magnetic alloys significantly.