A thermally stable FeCoNiAlSi multi-principal element alloy with excellent soft magnetic and mechanical properties

Multi-principal element alloys have attracted considerable research interest owing to their innovative compositional design theory and outstanding properties. In this work, Fe40Co(40-x)Ni10Al10Six (x = 0, 2, 4, 6, 8, 10) multi-principal element alloys are designed and fabricated. The microstructures, mechanical properties, and magnetic properties are investigated. Among these compositions, the Fe40Co30Ni10Al10Si10 multi-principal element alloy exhibits outstanding comprehensive properties, which shows a low coercivity of 1.80 Oe, a high saturation magnetization of 166 emu/g, and a high electrical resistivity of 136.93 mu Omega & sdot;cm, meanwhile, it exhibits outstanding mechanical properties, with the hardness value of 534 HV, yield strength of 1132 MPa, fracture strength of 1409 MPa and strain rate of 10.71 %. More importantly, its soft-magnetic properties are further enhanced after being thermally exposed at 1223 K for a duration of 24 h, achieving a coercivity as low as 0.99 Oe. The microstructural analysis results indicate that the alloy shows an excellent thermal stability with the crystal structure remaining unchanged, and no significant grain growth is observed following heat treatment. Its magnetic properties surpass most soft magnetic multi-principal element alloys reported so far, making it an ideal candidate for application as magnetic functional materials, especially in high temperature area.