Rapid solidification of undercooled FeCoNiCu multi-principal element alloy: Mechanical and tribological properties

Abstract

A FeCoNiCu multi-principal element alloy (MPEA) was undercooled and its microstructures, mechanical and tribological performance were investigated for different solidification conditions. All the microstructures were consisted of two phases, i.e., the primary Cu-depleted phase and the secondary Cu-rich phase. With the increase of undercooling, a transition of the primary phase from coarse dendrites to fine equiaxed grains happened and the volume fraction of the secondary phase decreased considerably. The primary phase was supersaturated by Cu at high undercooling and segregation of Cu was inhibited considerably by rapid solidification. Consequently, the hardness and yield strength were improved remarkably due to grain refinement strengthening and solution strengthening, and the wear volume was decreased significantly due to both improved mechanical properties and oxidation induced by friction. For the largest undercooling obtained in this study, (i.e., ΔT = 226 K), the yield strength was increased by about 50% and the wear volume was decreased by about 45% as compared with the as-cast case. The current work shows rapid solidification could be an effective way to modulate both mechanical and tribological properties of MPEAs and hence is helpful for their potential applications as engineering materials.