AZ31-calcium-deficient hydroxyapatite (CDHA) composites produced by friction stir processing: controlling the degradation by enhancing the biomineralisation

In the present work, calcium deficient hydroxyapatite (CDHA) was dispersed into the surface of AZ31 Mg alloy within the solid state by friction stir processing and the role of the refined microstructure and the presence of nano-CDHA on biomineralization and corrosion performance was investigated. Fine grains (1.6 ± 2.1 µm) have been produced in AZ31-CDHA composite compared with base alloy (41 ± 6.1 µm) and nano-CDHA was observed as reinforced into AZ31 matrix. X-ray diffraction analysis confirms the texture change due to FSP in the composite. Wettability studies carried out by measuring contact angles on the surface of the composites indicated increased surface energy (37.27 ± 5.1 mJ/m2) compared with the base alloy (20.55 ± 3.4 mJ/m2) . From the potentiodynamic polarization studies, lower corrosion current density (1.69 ± 1.13 × 10-5 A/cm2) was observed for the composite. From the immersion studies in simulated body fluids, higher level of biomineralization on the composite helped to decrease the degradation rate as reflected from the lower weight loss (7.5 ± 1.1 %) compared with the base alloy (12.1 ± 1.3 %). The results demonstrate the promising role of enhanced biomineralization on controlling the degradation of AZ31-CDHA composite..