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The tribological properties of Fe3Al-20 wt% Al2O3 composites, prepared by means of mechanical alloying and plasma-activated sintering, were investigated under air atmosphere against GCr15 bearing steels from room temperature to 500 °C. It was found that the friction coefficient of the composites (at 200 °C/350 °C) decreased with increasing temperature and the value was lower than that of Fe3Al alloys at the same temperature, and the friction coefficient increased again at 500 °C. Moreover, the wear rates of all the pins and discs were low at the medium/high temperatures. The dominant wear mechanism of the composites is microplowing and a little oxidation wear at room temperature. However, at elevated temperatures, oxidation wear and a little microplowing are found to be the main wear mechanism. There is also spalling induced by microfracture at 500 °C. The in situ Fe3Al-20 wt% Al2O3 composites have excellent wear resistance at a wide temperature range. [ABSTRACT FROM AUTHOR]

The article studies on the effect of slippage rate on frictional wear behaviors of high-tungsten high-speed steel (HTHSS) under high-pressure contact by using a self-made ring-on-ring wear machine. The microstructure of HTHSS is characterized by dual-scale tungsten carbides, including microscale eutectic M 6 C carbide [(Fe 0.55 W 0.30 Cr 0.08 Mo 0.07) 6 C] and nanoscale secondary M 6 C carbide. Slippage rate has a significant effect on frictional wear behaviors. The peak value of friction coefficient occurs at the slippage rate of 5.5%. The friction coefficient will reduce whether the slippage rate increases or decreases. However, the increase in slippage rate makes wear failure mechanism change from fatigue to scratch, causing continuously significant increase in wear weight loss. The roles of different scale M 6 C carbides in resisting wear were also discussed. Image 1 • Sliding-rolling frictional wear behaviors of HSS with micro-nano scales M 6 C were studied. • Slippage rate decides wear failure mode and therefore affects wear property of HSS. • High stress contact caused martensite transformation, contributing in delaying wear failure. • Micro-nano scales M 6 C play a different role under different slippage rate. [ABSTRACT FROM AUTHOR]