Self-lubricating behavior of Fe22Co26Cr20Ni22Ta10 high-entropy alloy matrix composites
(State Key Laboratory of Powder Metallurgy, Central South University, Changsha 410083, China)
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.
Key words: eutectic high entropy alloy; self-lubricating composite; BaF2/CaF2 eutectic powder; tribological properties; microstructure