To assess the usefulness of high-entropy alloys based on equimolar FeCoCrNi for magnetic application at high temperature, magnetic and vibrational properties of such materials were measured using vibrating sample magnetometry and nuclear resonant inelastic X-ray scattering. The HPCAT experiments show that the Fe partial phonon density of states of FeCoCrNi is similar to that of FeNi which has the same fcc structure. By adding the heavier Pd to the alloy, the mode energy of iron is decreased. The high energy optical modes between 40-50meV in FeCoCrNiAl2 indicated chemical ordering and formation of an Al-rich sublattice, which also confirmed by XRD experiments. High-entropy alloys based on FeCoCrNi were found to be poor candidates for soft magnetic applications, especially at elevated temperatures.
Lucas et al. J. Appl. Phys. 109, 07E307 (2011)