Biodegradable magnesium alloys and magnesium metal matrix composites (Mg/MMCs) in biomedical applications: a comprehensive state-of-the-art review based on materials, processing techniques, design, and application perspective

Magnesium (Mg)- based alloys and their composites have recently gained significant interest in the biomedical field as potential biodegradable materials due to their unique mechanical properties, bioresorbability, biocompatibility, and biological activity. Nevertheless, the widespread biomedical applications of Mg-based alloys and composites are still limited mostly by their superior corrosion rates and subsequent loss in mechanical integrity. In recent years, numerous research studies have been conducted to develop biodegradable Mg-based alloys and magnesium-based metal matrix composites (Mg/MMCs) with enhanced corrosion resistance and mechanical properties. In this paper, an effort has been made to discuss the various methodologies for processing biodegradable Mg/MMCs for important clinical applications. The major processing technologies for biodegradable Mg/MMCs, including liquid-state processing (e.g., stir casting), solid-state processing (e.g., powder metallurgy (PM)), in-situ processing, and modern additive manufacturing (e.g., powder bed fusion (PBF), selective laser melting (SLM), and wire arc additive manufacturing (WAAM)), are first briefly introduced. Subsequently, biodegradable Mg-based alloying designs and the current trend in biodegradable Mg-based alloys, including Mg/Ca, Mg/Zn, Mg/Cu, Mg/Sr, and Mg/RE, essential for biomedical applications, are reviewed in detail. This review article also comprehensively discusses the design of reinforcement materials for producing biodegradable Mg/MMCs for clinical applications. The current trends on biodegradable Mg/MMCs, including calcium phosphate (CaP)-based bioceramics, Si-containing bioceramics, biodegradable magnesium oxide (MgO), and carbon materials reinforced Mg/MMCs, are discussed. Special emphasis has been placed on the production techniques and various behaviors (e.g., mechanical properties, microstructure, biocompatibility, and corrosion behaviors) displayed by micro/nano-sized particles reinforced Mg/MMCs. The potential engineering applications of Mg/MMCs are also introduced. Ultimately, this review highlights the prospects of biodegradable Mg-based alloys and Mg/MMCs biomaterials in various biomedical applications. This review will serve as a valuable reference for young researchers and industry personnel with a comprehensive understanding of biodegradable Mg/MMCs utilized in biomedical applications.