Face-centered-cubic-structured (Co0.4Fe0.3Ni0.3)100-x(Al0.4Mn0.6)x high-entropy alloy with enhanced soft magnetic properties and tensile ductility

High saturation induction (B_s), low coercivity (H_C), and good formability are very important for the application of magnetic high-entropy alloys (MHEAs). Unfortunately, the coercivity (H_C) of these MHEAs is often located between ∼ 100 and 10,000 A/m, making them semi-hard rather than soft magnetic materials. In addition, most previous MHEAs have a body-centered-cubic (BCC) crystallographic structure or a mixture of BCC and face-centered cubic (FCC) structures and thus do not possess a high tensile ductility. Here, we report FCC-structured (Co_0.4Fe_0.3Ni_0.3)_100-x(Al_0.4Mn_0.6)_x MHEAs with excellent soft magnetic properties and high tensile ductility. Our as-cast FCC (Co_0.4Fe_0.3Ni_0.3)₉₅(Al_0.4Mn_0.6)₅ MHEA has B_S of 1.44 T, H_C of 44.8 A/m, and total tensile elongation of 52 %. After annealing at 1200 °C, the B_S increases to 1.51 T, the H_C decreases to 40.6 A/m, and the total elongation slightly increases to 54 %. Such an outstanding combination of high B_S (∼1.5 T), low H_C (∼40 A/m), and exceptional tensile ductility (∼54 %) is much superior to that achieved in previous MHEAs. The structure-property relations are analyzed to explain the good magnetic and mechanical performances achieved in the present FCC-structured MHEAs. The present study should help design a new type of magnetic materials with both attractive magnetic properties and superior processability.