Observation of the microstructure and characterization of local mechanical properties of AM50 using a micro-indentation technique

The microstructure of die cast magnesium alloys varies significantly with the depth from the casting surface. Optical and SEM metallography showed that grain size gradually increases with increase in depth from the casting surface. To characterize the local deformation behavior of the region adjacent to the casting surface, a micro-indentation technique has been used. The paper describes the time-dependent mechanical response of AM50 subjected to a shallow indentation made by a three-sided pyramidal (Berkovich) diamond indenter at room temperature. Both of hardness and composite modulus were obtained by measuring the change in penetration depth with time during testing. The creep behaviors were compared for the regions with different microstructures.