Wear properties of NiAl based materials

The NiAl based materials including NiAl–TiC–Al2O3 composite, NiAl–Cr(Mo)–Hf–Ho eutectic alloy and NiAl–Cr(Mo)–CrxSy in situ composite were fabricated and their wear properties were tested at different temperatures. The results revealed that the NiAl–TiC–Al2O3 composite, NiAl–Cr(Mo)–Hf–Ho eutectic alloy and NiAl–Cr(Mo)–CrxSy in situ composite exhibited the excellent wear properties between 700 °C and 900 °C. The microstructure observations exhibited that the self-lubricant films formed on the worn surfaces during the dry sliding test at high temperature, which decreased the wear rate and friction coefficient significantly. TEM observation on the self-lubricant film revealed that it was mainly comprised by ceramic amorphous and nanocrystalline. Compared with the NiAl–TiC–Al2O3 composite, the NiAl–Cr(Mo)–CrxSy in situ composite has lower friction coefficient at low temperature. Such phenomena may be ascribed to the addition of sulfide which contributes much to the formation of self-lubricant, and moreover the TiC addition increase the strength of NiAl based material and its wear resistance.