Metal matrix composites (MMCs) are a family of strong yet lightweight materials that have many industrial uses, particularly in the automotive, aerospace, and thermal management industries. By choosing the best combinations of matrix, reinforcement, and manufacturing techniques, the structural and functional features of MMCs may be adjusted to meet the requirements of diverse industrial applications. The matrix, the interaction between them, and the reinforcement all affect how MMCs behave. Yet, there is still a significant problem in developing a large-scale, costeffective MMC production method with the necessary geometrical and operational flexibility. This chapter provides an overview of Metal Matrix Composites (MMCs), their historical development, properties of MMCs, classification of MMCs, diverse applications, and the relevance of MMCs to sustainable industries.
The current work takes the benefit of utilizing a composite approach by reinforcing Mg with Zn, Cerium oxide - a rare earth and bone-friendly ceramic, and bioactive hydroxyapatite to develop magnesium-based MMCs for high structural integrity and low degradation inside the human body via stir casting technique in a protective Ar-SF6 environment. The friction stir processing (FSP) technique was employed to tailor the properties of as-cast Mg composites, resulting in further grain refinement and better dispersion of reinforced materials. Phase and microstructure analysis were analyzed via XRD, FESEM, and optical microscopy. During tensile tests, as-cast Mg-5Zn-1HA-1.5CeO2 improved 68.6% in yield strength and 16.3% in ultimate tensile strength. After FSP, the same composite resulted in an overall improvement of 114.6% in yield strength and 31.9% in ultimate strength compared to as-cast pure Mg. Dispersion of inert bioceramics within the Mg matrix results in higher polarization resistance as per Electrochemical impedance spectroscopy (EIS). At the same time, a remarkable 81.6% reduction in H2 emission and an 84.4% decrement in corrosion rate were found during the immersion study for Mg-5Zn-1HA-1.5CeO2 composites. All Mg-based composites exhibited no cytotoxicity as cell viability evaluated via MTT assay was found to be greater than 80% for 50% and 25% extract concentrations. The composite's hemolysis rate was below 5%, indicating acceptable hemocompatibility. This work provides insight into developing rare earth oxide-incorporated Mg composites with better mechanical capabilities and degradation resistance while avoiding the long-term cytotoxicity of rare-earth materials.
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