Ageing on mechanical and microstructural properties of aluminum-silicon metal matrix a: A review

This review examines the impact of ageing on the mechanical and microstructural properties of Aluminum-Silicon (Al-Si) Metal Matrix Composites (MMCs), extracting broader perspectives from experimental and theoretical studies. Al-Si MMCs have gained significant attention in various industries as a pivotal material in advanced engineering applications due to their excellent strength, exceptional thermal stability, corrosion resistance, lightweight nature and wear resistance properties. Nevertheless, the long-term performance of the composites is significantly influenced by thermal and mechanical ageing phenomena, which alter their microstructural configuration and mechanical integrity.  Thus, fundamental ageing mechanisms such as precipitation hardening, coarsening of reinforcement particles, matrix-reinforcement, interfacial reactions and micro-crack initiation are explored in relation to ageing conditions, percentage volume fractions of reinforcement and alloying elements. Further emphasis is placed on the correlation between microstructural evolutions; including grain refinement, intermetallics phase transformation and particles distribution, noting their influences on the tensile strength, hardness, wear resistance and fatigue behaviour of the composites. More so, various ageing treatments such as natural, laboratory accelerated (artificial) and over-ageing influence dislocation movements and interfacial bonding; thereby affecting overall performance of the material. In addition, emerging trends in nano-structured MMCs and advanced ageing models for prediction of materials’ performance are discussed. Thus, this review provides a foundational understanding for materials engineers and researchers aiming to tailor Al-Si MMCs through controlled ageing for improved service performance and lifecycle efficiency; as the findings herein underscore the critical role of optimized ageing treatments in enhancing the reliability and longevity of Al-Si MMC components in automotive, aerospace and structural applications. Future research directions are proposed, focusing on hybrid reinforcement systems and real-time monitoring of ageing-induced degradation in engineering systems.