Experimental Research on Microhardness and Wear Resistance of MB8 Magnesium Alloy Treated by Ultrasonic Impact

The surface of MB8 wrought magnesium alloy was treated by HJ-III type ultrasonic impact treating (UIT) machine. The microstructures of the treated surface were analyzed by an optical microscope, and the grain refining mechanism of UIT was investigated by High Resolution Transmission Electron Microscopy (HRTEM). The wear resistance of MB8 wrought magnesium alloy was experimentally researched both with the treated and untreated specimens. The effect of UIT process on the microstructure and microhardness were also investigated using scanning electron microscope (SEM) and microhardness tester. The results indicate that the grains on the top surfaces of MB8 are highly refined. The severe plastic deformation is formed by UIT, and the thickness of the plastic deformation layer is approximately 180 µm. The microhardness and wear resistance of the treated surface layer of MB8 can be enhanced significantly compared to that of the untreated specimens. The longer the UIT time, the greater of the microhardness and wear resistance the treated surface layer of MB8 will be. When the impact current is 1.2 A and impact time is 6 min, the microhardness and wear resistance of the treated sample is about 102.8% and 51.83% higher than that of the untreated specimen, respectively.