Studies on Bio-acceptability of Thermo-Mechanically Processed Mg-4Li-0.5Ca Alloy and Its Microstructural Correlation

In this study, in vitro corrosion behavior of rolled Mg-4Li-0.5Ca (wt.%) alloy at three temperatures (250, 300 and 350 °C) with 75% reduction and subsequent short annealing at 200 °C for 10 min was systematically investigated. Microstructural evaluation, Mg₂Ca precipitation and defects like twins were characterized by an optical microscope, scanning electron microscope and x-ray diffraction. Micrographs reveal an increase in grain size and comparatively reduction in twins density population with an increase in hot rolling temperature and subsequent short annealing. In vitro corrosion tests like dynamic bio-corrosion immersion test, hydrogen evolution test and electrochemical linear polarization test were carried out in simulated body fluid. From in vitro corrosion tests, it is observed that the alloy rolled at 350 °C and subsequently short-annealed shows better bio-corrosion resistance than other hot-rolled and short-annealed alloys. This is due to low twins density and uniformly dispersed Mg₂Ca compound throughout the matrix.