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

Abstract

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°C. This was particularly true of the AlCrCuFeMnNi, Al0.8CrCuFeMnNi, and Al0.8CrCuFe 1.5MnNi alloys. These alloys may therefore have great potential for use in structural parts and tools operating up to 800°C. © Lavoisier.