Wear behaviour of AZ91D magnesium alloy with a nanocrystalline surface layer

The tribological behaviour of nanocrystalline surface layer with an average grain size of 30 ± 5 nm generated by surface mechanical attrition treatment on AZ91D Mg alloy samples has been investigated under dry sliding conditions. Compared with the alloy without SMAT, nano-grained surface layer showed lower friction coefficient. An improved wear resistance of the NC layer was found at the load ranges from 3 N to 9 N due to the grain refinement strengthening effect. Examination of the worn surface and the wear debris indicated that the wear mechanism of NC layer is similar to that of the coarse-grained alloy. Cooperative effects of cutting, plowing and oxidation govern the tribological behaviour of nanocrystalline AZ91D Mg alloys.