From oxide disruption to strength-ductility optimization: a review of sintering methods, microstructural evolution and mechanical properties of Al alloys

Al powder metallurgy offers a promising route for producing lightweight, near-net-shape components with controlled composition and microstructure; however, its wider structural application is restricted by the stable native Al₂O₃ film, incomplete densification and weak interparticle bonding. This review critically examines how conventional, pressure-assisted, field-assisted, microwave, flash, induction and hybrid sintering routes influence oxide-film disruption, liquid-phase formation, pore elimination, grain evolution, precipitation behaviour and interface development in Al and its alloys. Special emphasis is placed on the processing-microstructure-property relationship governing hardness, tensile strength, ductility, fatigue, wear resistance and fracture behaviour. The review compares pure and low-alloyed Al, Al-Cu/2xxx, Al-Mg-Si/6xxx, Al-Zn-Mg-Cu/7xxx, Al-Si/hypereutectic systems and Al-based composites to show that the optimum sintering route is alloy-system dependent rather than universal. A unified processing-structure-property framework is proposed to link sintering strategy with densification mechanism, microstructural control and mechanical response. Finally, key research gaps are identified, including limited oxide-network characterization, weak ductility/fatigue correlation, poor standardization of sintering parameters and the need for data-driven process maps for next-generation sintered Al alloys. Comprehensive comparison of conventional, pressure-assisted, field-assisted, microwave, flash and hybrid sintering routes for Al powder metallurgy. Critical evaluation of oxide-film disruption mechanisms governing densification and interparticle bonding. Correlation of sintering route, microstructural evolution and mechanical properties across major Al alloy systems. Identification of alloy-specific processing strategies for optimizing strength, ductility and densification. Mechanistic insights are provided to enable rational selection of sintering routes for targeted Al alloy applications.