Magnesium-based bioceramic-enhanced composites fabricated via friction stir processing

Abstract

Improving the degradation performance and enhancing the biocompatibility are the main challenges of Mg-based biodegradable implants. In this study, a nano-hydroxyapatite-enhanced (nHA) Mg matrix composite was fabricated via friction stir processing and characterised, including microstructure, mechanical, in vitro degradation properties, and cytocompatibility. Hydroxyapatite is renowned for its superior bone compatibility, promoting healing responses and tissue growth. Friction stirring created a gradient grain structure in the alloy, with the stir zone exhibiting the highest grain refinement. The stir zone also contained most of the incorporated nHA and exhibited a strong texture with grains preferentially oriented along the [0001] direction. Immersion and polarisation experiments showed an increase in the FSPed WE43-nHA's corrosion resistance due to the refined microstructure. The treatment also caused a shift in the corrosion mode of the alloy from localized to uniform corrosion despite some localized corrosion associated with the nHA. Cytocompatibility tests in human osteoblast (HOB) cell lines indicated good biocompatibility in the Mg-nHA alloy, with cells exhibiting relatively healthy morphology and increased live cell count. Friction stir processing is a viable manufacturing option for creating Mg-based metal matrix composites with improved corrosion resistance and good biocompatibility.