Microstructure and Properties of Al₂O₃/Fe-28Al-5Cr Composites Prepared by In-situ Reaction and Hot-Pressing Sintering

Fe-28Al-5Cr based composites with 10wt% and 20wt% in situ formed Al2O3 ceramic were produced by hot-pressing sintering method. Their phase, microstructure, mechanical properties and the friction and wear properties at room temperature, 200, 400, 600, 800 ℃ were investigated. In addition, as contrast materials, Al2O3/Fe-28Al-5Cr composite was produced by the method of adding Al2O3 ceramic directly. The results show that the composites in-situ formed Al2O3 ceramic were composed of Fe3Al and Al2O3 phases, and Al2O3 distributed predominately on the grain boundary of Fe3Al. The hardness of the composites increased gradually but the bending strength decreased dramatically with increasing Al2O3 content, and when the mass fraction of Al2O3 was 20%, the wear resistance of the composite was obviously improved. Compared with the composite prepared by directly adding 20% Al2O3, the composite in-situ formed Al2O3 ceramic possessed higher hardness and strength and lower wear rate at room temperature, 200 and 800 ℃.