Wear behavior of nanocrystalline structured magnesium alloy induced by surface mechanical attrition treatment

An Mg-6Gd-3Y-0.5Zr (GW63K) magnesium (Mg) alloy with nanocrystalline surface layers was synthesized by using surface mechanical attrition treatment (SMAT). The wear behavior of the nanocrystalline structured alloy has been studied by dry sliding wear tests, 3D optical profiler, scanning electron microscope and energy-dispersive spectrometer. Together with the as-received alloy, a comparison between microcrystalline (MC) and nanocrystalline (NC) structured Mg alloys in wear behavior was performed. The result shows that the NC structured layer induced by SMAT exhibits worse wear resistance than MC alloy, which is related to the variation of wear mechanism under different sliding speeds. Under abrasive wear condition with sliding speed of 0.05 m/s, the poor wear resistance of NC layer is attributed to its low ductility and toughness, which leads to surface fracture. Under the high speed of 0.2 m/s, the wear mechanism transfers into oxidative wear leading to a low friction coefficient and wear mass loss. However, delamination mechanism performs simultaneously for the NC alloy, which greatly reduced wear resistance of the layer.