SYNTHESIS, CHARACTERIZATION AND WEAR BEHAVIOR OF CO0.5 CR CU0.5 FE NI1.5 AL TI0.4 AND CO CR FE NI AL0.25 TI0.75 HIGH ENTROPY ALLOY (HEA) PREPARED BY MECHANICAL ALLOYING

Structure-tribological property relations have been studied for two high entropy alloys (HEAs). Microhardness, room temperature sliding friction coefficients and wear rates were determined for two HEAs: Co0.5CrCu0.5Fe Ni1.5AlTi0.4 and Co Cr Fe Ni Al0.25 Ti0.75. Wear surfaces were characterized with scanning electron microscopy and micro-Raman spectroscopy to determine the wear mechanisms and tribochemical phases, respectively. It was determined that the both HEAs exhibit an excellent balance of high hardness and lower wear rates compared to 440C stainless steel, a currently used bearing steel. This was attributed to their more ductile body centered cubic (BCC) solid solution phase along with the formation of tribochemical Cr oxide and Ti oxide phases, respectively, in the wear surfaces. This study provides guidelines for fabricating novel, low-friction, and wear-resistant HEAs for potential use at room and elevated temperatures, which will help reduce energy and material losses in friction and wear applications.