Improving the hardness and wear resistance of magnesium alloys by TIG composite surfacing with Al+Al2O3

In the present study, an attempt has been made to improve the surface properties of magnesium alloys,AZ91D and AZ31, through formation of the surface composite layers with Al+Al2O3 (3:1) powder by using a Tungsten Inert Gas (TIG) process as a heat-generation source. Microstructures of composited layers were studied by optical microscope (OM) and scanning electron microscope (SEM), and phases were indicated by X-ray diffraction (XRD). The microhardness of the surface composite layers was measured and their wear behavior was also evaluated. Due to the presence of the intermetallic phase Mg17Al12 and almost uniform distribution of the ultra-hard Al2O3 ceramic particles in the grain refined Mg-rich matrix, the hardness and wear resistance of the composite coatingswere considerably improved as compared to the as-received specimens. The surface hardness increased from 80 HV0.1 and 55 HV0.1 for AZ91D and AZ31 magnesium alloys to as high as 214 HV0.1 and 230 HV0.1 for coated samples, respectively. The wear rates of composited layers were also reduced to almost 30% for both alloys

کلیدواژه ها:

magnesium alloys ، surface composite layer ، TIG ، Al ، Al2O3