The microstructure and tribological property of in-situ Al ₂O₃/Fe-25Al composites in argon atmosphere

In-situ 20 wt.%Al₂O₃/Fe-25Al composites were prepared by mechanical alloying (MA) inducing self-propagating reaction (SHS) with subsequent plasma activated sintering (PAS). The density and hardness of the composites were 99.2% and 56.9 HRC, respectively. The tribological properties of 20 wt.%Al₂O₃/Fe-25Al composites under dry sliding against GCr15 bearing steels from room temperature to 773 K in argon atmosphere were investigated. The results show that the friction coefficients of 20 wt.%Al ₂O₃/Fe-25Al composites are in the range of 0.47-0.88 at the given testing conditions, and they decrease with increasing temperature at first, then increase again at 773 K. Similarly, the wear rates of Al ₂O₃/Fe-25Al composites are much lower than that of Fe-25Al alloys. The wear rates of the composites are higher at room temperature but dramatically decrease with increasing temperature. At 773 K, the wear rates of the composites and the counterpart GCr15 bearing steel disk are on the order of 0.03 (10^-3 mm³/Nm). The dominant wear mechanism of 20 wt.%Al₂O₃/Fe-25Al composites is microploughing with a little oxidation wear and adhesive wear at room temperature. The main wear mechanism is transferred to adhesive wear with increasing temperature, especially at 773 K, the wear mechanism is mainly adhesive wear.