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)–Cr_xS_y 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)–Cr_xS_y 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)–Cr_xS_y 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.