Investigations on the surface topography, corrosion behavior, and biocompatibility of friction stir processed magnesium alloy AZ91D

Magnesium and its alloys have been identified as potential biodegradable implant materials for orthopaedic applications considering their bone equivalent density, biocompatibility, and biodegradability. However, the rapid corrosion rate of magnesium alloys in the physiological environment is a severe problem. This study attempts to simultaneously improve the microhardness and reduce the corrosion rate of AZ91D alloy by friction stir processing. Magnesium alloy AZ91D is friction stir processed by varying the process parameters namely tool rotation speed and tool traverse speed. The effects of friction stir processing parameters on the microstructural evolution, surface topography, microhardness, and corrosion rate of AZ91D alloy are investigated using the hybrid models, which are developed by integrating the quadratic function and radial basis function. The results indicate that the optimum process parameters for friction stir processing of AZ91D alloy is 750 rpm and 45 mm min−1. Cytotoxicity test revealed that the biocompatibility of friction stir processed AZ91D alloy is in good agreement with the biocompatibility of the AZ91D alloy.