Effect of the substitution of Co by Mn in Al-Cr-Cu-Fe-Co-Ni high-entropy alloys

In order to determine whether more cost effective alloys with equivalent, or possibly superior, properties can be developed, Co shall be replaced by less-expensive Mn in the Al-Co-Cr-Cu-Fe-Ni alloy system. The addition of Mn was found to enhance the formation of a BCC structure and inhibit Cu segregation to the interdendrite region. These changes, particularly the formation of a stronger BCC phase, led to a hardness increase of about 100 to 200 HV for the Mn-containing alloys. Moreover, the ordering of the B2 phase that occurs for Co-containing alloys was suppressed when using Mn, which in turn improved the toughness. The Mn-containing alloys were also found to exhibit an excellent age hardening phenomenon at 800 degrees C. This was particularly true of the AlCrCuFeMnNi, Al0.8CrCuFeMnNi, and Al0.8CrCuFe1.5MnNi alloys. These alloys may therefore have great potential for use in structural parts and tools operating up to 800 degrees C.