Wear mechanism of AZ31 magnesium alloy irradiated by high-intensity pulsed ion beam

The wear resistance and wear mechanism of AZ31 magnesium alloy irradiated by high-intensity pulsed ion beam (HIPIB) at an ion current density of 100 A/cm2 with shot number from one to ten are investigated by dry sliding wear tests. The cross-sectional microstructure and surface microhardness of the irradiated AZ31 magnesium alloys are examined by optical microscopy (OM) and Vickers tester, respectively. It is found that surface hardness increased with increasing shot number, from an original value of 570 MPa to a maximal value of 820 MPa with ten shots, and the wear rate of the samples irradiated with five and ten shots was about one order of magnitude less than that of the original sample. The transition from severe metallic wear to mild oxidative wear induced by HIPIB irradiation was identified through a combined analysis in surface morphology and chemical composition of wear tracks, mechanically mixed materials, wear debris and wear scars of counterface steel ball by using scanning electron microscopy (SEM) and electron probe microanalysis (EPMA), which is mainly attributed to the significant increase in microhardness resulting from grain refinement on the irradiated surface.