Microstructure and wear performance of Ni-20 wt.% Pb hypomonotectic alloys

The tribological properties of Ni-20 wt.% Pb alloys were measured by using a ball-on-disc 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-20 wt.% Pb was examined using scanning electron microscopy (SEM) and X-ray photoelectron spectroscopy (XPS). The results show that the wear properties of the samples undercooled by 85 and 390 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 Ni ₂O₃ and lead oxide by XPS analysis. At the same load or sliding speed, the predominant wear mechanisms can be identified as oxidative wear for the lower and larger undercooling and plastic deformation for the medium undercooling.