Effect of strong magnetic field on the microstructure and mechanical-magnetic properties of AlCoCrFeNi high-entropy alloy

While there have been multiple recent reports in the literature of exceptional mechanical properties in high-entropy alloys (HEAs) which tried to tackle the barrier of the “strength-ductility trade-off”, the research of how strong the magnetic field affects mechanical and magnetic properties of HEAs is still preliminary. This paper shows that applying strong magnetic field during heat treatment can tailor the microstructure and improve both mechanical and magnetic properties of AlCoCrFeNi HEAs compared with those without the magnetic field. After applying 6 T magnetic field, the magnetic difference between the product and parent phase would change the Gibbs free energy of phase transformation. The volume fraction of BCC phase would increase slightly and the volume fraction of FCC and σ phases would decrease subtly, leading to a slightly higher saturation magnetization, ultimate compressive strength and plastic strain. Therefore, an excellent combination of saturation magnetization (∼89 emu/g), electrical resistivity (∼188 μΩ/cm), yield strength (∼1231 MPa), ultimate compressive strength (∼2708 MPa) and compressive plastic strain (∼26%) was achieved when applying 6 T magnetic field at heat treatment temperature of 1200 °C. This work provides a potential approach for future development of soft magnetic materials, with more preferable mechanical, electrical and magnetic properties.