Effect of filler morphology on mechanical behaviour of Mg/HA nanocomposites for degradable implant applications

Abstract Magnesium (Mg) alloys exhibit promising potential for biodegradable orthopaedic applications, with the incorporation of hydroxyapatite (HA), which offers a means to tailor their bioactivity and biodegradation behavior. In this study, the effect of filler morphology on mechanical behaviour and biocorrosion of the Mg/HA composites is analysed. Two distinct morphologies of nano-hydroxyapatite (nHA), needle-like and flake-shaped, were incorporated into Mg using a stir-casting technique. The incorporation of nHA led to a notable increase in hardness, with enhancements of 15% for needle-like nHA and 29% for flake-like nHA. Moreover, the ultimate compressive strength exhibited a significant improvement of 29% for the flake-shaped nHA and 12% for the needle-like nHA. Interestingly, the morphological variation did not impact the degradation behaviour of the composites. Based on these findings, it is proposed that Mg metal matrix composites utilizing bioactive flake-shaped nHA as a filler material hold promise for enhancing the mechanical properties of Mg/HA nanocomposites, particularly for load-bearing implant applications.