Role of deformation assisted processing in tailoring the microstructure and strength of Al–Mg–alumina composites

Al–Mg matrix composites reinforced with alumina particles were fabricated via deformation-driven metallurgy (DDM) to clarify the effects of reinforcement content and severe deformation on microstructure and performance. AA5083 alloy chips were consolidated with 0–18 wt.% Al2O3 at an optimised rotational speed of 700 rpm, achieving full densification and complete metallurgical bonding in all conditions. Grain size decreased with increasing alumina content up to 9 wt.% due to deformation-induced dynamic recrystallization, followed by partial coarsening at higher contents as a result of enhanced thermal exposure and particle agglomeration. Microhardness increased continuously from 128.4 ± 2.1 HV0.1 to 228.9 ± 9.2 HV0.1 with increasing Al2O3 addition. Tensile properties reached an optimum at 9 wt.% Al2O3, where yield strength and ultimate tensile strength increased to 259.2 and 361.8 MPa, respectively, while maintaining 15.4% elongation. Tribological performance was also maximised at this reinforcement level, yielding a minimum friction coefficient of 0.44 ± 0.03 and wear rate of 4.7 ± 0.2 µg/m. The novelty of this study lies in systematically examining the interplay between rapid DDM processing, Al2O3 particle distribution, and microstructural evolution in Al–Mg matrix composites, providing new insights into optimising mechanical and tribological properties for high-performance applications.