A novel low-density semi-hard magnetic Al_(20)Fe_(20)Mg_(20)Ni_(20)Ti_(20) high entropy alloy

摘要

A relatively low density nanocrystalline high entropy alloy (HEA) with a nominal composition of Al_(20)Fe_(20)Mg_(20)Ni_(20)Ti_(20) is synthesized through the mechanical alloying process. The synthesized HEA is comprised of the mixture of bcc and fcc solid solution with crystallite size of the order of 6 to 7 nm. To understand the phase stability, the synthesized HEA is annealed at 200 °C and 500°C for 2 hr. The 200°C annealed HEA does not show any significant change in the XRD pattern. However, annealing at 500 °C affects the relative volume fraction of the formed phases. The synthesized Al_(20)Fe_(20)Mg_(20)Ni_(20)Ti_(20) HEA showed better magnetic characteristics with Ms (54.28 emu/g) and Hc (43.4 Oe) as compared to the many of recently reported HEAs. Moreover, for 200°C annealed HEA, the found value of Ms (54.92 emu/g) and Hc (42.4 Oe) is similar to the as-synthesized HEA. An interesting change in magnetic behaviour has been observed after annealing at 500°C, which may be related to the change in the fcc to bcc phase volume and change in the lattice parameter of these phases.