Highly tunable magnetic and mechanical properties in an Al_0.3CoFeNi complex concentrated alloy

Electrical rotating machines, including motors, account for a significant portion of total energy consumption in the world. Improving the magnetic materials used in motors is a key challenge to increase their performance. Specifically, higher rotation frequency requires appropriate site specific magnetic properties as well as good mechanical properties. Hence, we studied both the magnetic and mechanical properties of an Al_0.3CoFeNi complex concentrated alloy (CCA). Heat treatment, guided by phase diagram modeling, was employed to develop a novel eutectoid-like nano-lamellar (FCC+L1₂) / (BCC+B2) microstructure as well as a coarser FCC+B2 microstructure. The coarser microstructure exhibits soft magnetic properties with saturation magnetization (Ms) of ~127 emu/g, coercivity (Hc) of ~151 A/m and microhardness of ~ 195 VHN. On the other hand, the semi-hard nano-lamellar microstructure exhibits Ms ~138 emu/g, a high Hc ~12,732 A/m and a very high microhardness ~ 513 VHN. This corresponds to more than eighty times increase in Hc and double the hardness in the same alloy. These results demonstrate the feasibility of producing a range of mechanical and magnetic properties by thermo-mechanical treatment of a single CCA composition, making them potential candidates for metamorphic manufacturing.