Because of the light weight of magnesium, it has got potential applications in automobile industry. But magnesium has many limitations and due to that it cannot be used directly as a replacement of aluminium and steel. In past, different alloys of magnesium have been developed to overcome the limitations of magnesium without losing other physical and mechanical properties. One of the most important magnesium alloys is AZ91, which gives better properties than magnesium. In the present investigation, commercially available rectangular block of as cast AZ91 magnesium alloy of size 10×10×10? mm3 was heat treated at 390°C for 48?h in air and then water quenched to dissolve all the precipitates into matrix. Electron back scattered diffraction (EBSD) analysis of heat-treated sample was done on a field emission scanning electron microscope to know the crystallographic orientations of the individual grains present in the heat treated AZ91 magnesium alloy. Hardness and scratch resistance for the three different crystallographic orientations such as basal, prismatic and pyramidal orientations of AZ91 magnesium alloy grains was measured using an universal nanomechanical tester having Berkovich diamond indenter. Hardness and scratch resistance are found to vary with the variation in crystallographic orientations of the grains. Further wear resistance of these three different grains having basal, prismatic and pyramidal orientations, respectively were measured by atomic force microscopy and correlated with their measured hardness value.
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