The scratch behaviour of AlxCoCrFeNi (x=0.3 and 1.0) high entropy alloys

The wear behaviour of as-cast Al1.0CoCrFeNi with a body-centred cubic (BCC) structure and Al 0.3CoCrFeNi with a face-centred cubic (FCC) structure in the as-cast, homogenized and recrystallized conditions was studied by determining the intrinsic response to abrasive scratch testing. For the FCC material, the wear mechanism was qualitatively the same for the as-cast, homogenized and recrystallized conditions. The wear rate increased with increasing load, and the fraction of material removed from the groove (f) fell in the range of 0.2-0.7. The wear rate for the as-cast BCC material was significantly lower, which was ascribed to its high hardness. The f value for the BCC material lay in the range of 0.7-0.9, which implies dominance of the cutting wear mechanism. A wear map was constructed to enable comparison of the wear performance of materials under different loading conditions. It was found that the importance of hardness in wear is dependent on load. At high loads the wear performance of alloys highly depends on the scratch hardness. For low loads, however, the combination of scratch hardness and scratch ductility dictates total material loss.