Ni3AI intermetallic particles as wear-resistant reinforcement for Al-base composites processed by powder metallurgy

The suitability of Ni3Al intermetallics as reinforcement for Al-base materials for tribological applications has been investigated. For this purpose, an Al/Ni3Al (5 vol pet) composite was prepared by powder metallurgy and tested in air against steel counterfaces at the load range of 45 to 178 N. For comparison, unreinforced Al specimens were processed and tested under the same conditions. Tribological behavior was evaluated by microstructural examination of wear-affected zones and weight-loss measurements of specimens and counterfaces. It was found that a significant amount of Fe-rich oxide particles become incorporated into the Al matrix during wear, forming a cracked tribolayer. The wear behavior of Al/Ni3Al composite as a function of the applied load was not accurately reflected by the weight loss of worn specimens. Results highlight the role of Ni3Al particles as loadbearing elements due to their excellent bonding to the Al matrix, their interfaces withstanding the wear stresses even at the highest applied load. Moreover, Ni3Al particles limited the incorporation of wear debris to the Al matrix and reduced wear damage occasioned to the steel counterfaces compared to that of pure aluminum specimens.