Improving the Wear Resistance of a Magnesium Alloy by Laser Melt Injection

Abstract

The objective of this study is to improve the sliding wear resistance of the AZ91 E magnesium alloy, by means of dispersion of hard particles on its surface. Two kinds of powder and injection methods were applied. SiC powder, fed by Ar gas stream, was injected directly into a melt pool formed by laser beam. And the hypereutectic aluminum-silicon alloy was also injected in order to crystallize the fine Mg 2 Si intermetallic compound. These modified surfaces were evaluated by sliding wear test. SiC powder is dispersed uniformly at the surface of the AZ91E alloy, in proportion to the powder feeding rate. In the case of hypereutectic aluminum-silicon alloy, fine dendritic Mg 2 Si compound is crystallized uniformly. The matrixes of the modified layers changes from Mg solid solution to Al solid solution according to the powder feeding rate. And hardness of the layers are also changed. The wear depth of the SiC injected layer is almost zero, while that of the pin is increased by the sliding wear test. The modified layer using Al-30Si powder with the high powder feeding rate shows shallow wear depth and wear depth in the pin is also low.