Tribological property and wear mechanism of undercooled Ni-Pb monotectic alloys

The tribological properties of Ni-31. 44%Pb monotectic alloys were measured by using a SRV reciprocating tribo-tester. The effects of load, sliding speed and melt undercooling on wear rate of the sample were investigated. The worn surface of Ni-31. 44%Pb was examined using scanning electron microscope (SEM) and X-ray photoelectron spectroscope (XPS). The results show that the wear properties of the samples undercooled by 80 K and 310 K are obviously superior, which is attributed to more efficient transfer of Pb from the bulk material to the worn surface. The lubricating film is identified as a mixture of Ni₂O₃ and PbO by XPS analysis. At the same load and sliding speed, the predominant wear mechanisms can be identified as oxidative wear for the lower and larger undercooling, and plastic deformation and fracture for the medium undercooling.