Microstructural characterization, oxidation behavior, and properties of a new Al–Cu–Ni–Mn–Si non-BCC high entropy alloy at 600, 700, and 800 °C

Non-BCC high entropy alloys have been created and characterized in their as-cast and oxidized condition. The effect of Si on the microstructures in Al–Cu–Ni–Mn alloy has also been explored. The microstructure remained unaltered by the addition of Si. It has been observed that the addition of Si only changes the composition of the three phases that have been identified. Three phases with elements rich in: (a) Ni, (b) Mn, and (c) either Al–Cu–Ni in quaternary alloy or Al–Cu–Mn in Si alloy have been observed. It is suggested that Si draws Ni out of solution for Al–Cu–Ni rich phase in preference for Mn. Macrohardness (HRB) of the two alloys and microhardness (HV) of the three phases were found to be HRB 74 for the Al–Cu–Ni–Mn alloy and HRB 114 for the Al–Cu–Ni–Mn–Si alloy; and HV 265 to HV 271 for the Al–Cu–Ni-Mn alloy phases and HV 411 to 968 for the Al–Cu–N–Mn–Si alloy phases.