Self-lubricating behavior of Fe22Co26Cr20Ni22Ta10 high-entropy alloy matrix composites

Abstract

Eutectic high entropy alloys (EHEAs) have high temperature stability, good mechanical properties, and are promising for tribological applications at high temperatures. To study the high temperature lubrication behavior, Fe22Co26Cr20Ni22Ta10−(BaF2/CaF2)x (x=3−20, wt.%) composites were prepared by spark plasma sintering (SPS), with BaF2/CaF2 eutectic powder used as solid lubricant. The lubrication behavior and mechanical properties were studied at both room and high temperatures. With the increase of the content of BaF2/CaF2 eutectic powder, the friction coefficients and the wear rates of the composites at 600 and 800 °C decrease significantly. The composites with eutectic powder content of 15 and 20 wt.% have the best lubricating performance at 600 °C, with low friction coefficient and wear rates, mainly due to the good mechanical properties of EHEA matrix, the lubrication effect of BaF2/CaF2 phase and the oxides formed on the worn surface.