افزایش خواص مکانیکی و تریبولوژیکی آلیاژهای آلومینیوم غنی از Mg2Si توسط پردازش اصطکاک چند پاس

Particle strengthening of in-situ Al-Mg₂Si composites hinges on effective geometrical parameters (size, distribution, morphology, and volume fraction) of the inherent primary Mg₂Si particles. The use of solid-state friction stir processing (FSP) in a multi-pass mode is recognized as a secondary processing route capable of achieving desirable geometrical parameters of Mg₂Si particles in Al-Mg₂Si composites as compared to other routes. This paper thus studies the microstructure, mechanical properties, and tribological behavior of the multi-pass FSPed in-situ Al-25Mg₂Si composite with a threaded triangular pin tool. The FSP was conducted at constant tool rotational and traverse speeds of 1000 rpm and 80 mm/min for 1–6 passes. The results showed a decline in the average Mg₂Si size (115–3.25 μm), porosity content (5.8–0.14%), and primary Mg₂Si particle-depleted region as the FSP passes are increased (0–6). Improved geometrical parameters of the primary Mg₂Si particles enhance microhardness (178–272 HV), tensile strength (102–233 MPa) and wear resistance of the Al-25%Mg₂Si composite via particle dispersion and dislocation strengthening effects, grain refinement, and microstructural densification. Multi-pass FSP can be adopted as a better substitute to element addition, casting modification, heat treatment and electromagnetic stirring in effectively controlling the geometrical parameters of the primary Mg₂Si in in-situ Al-Mg₂Si composites for improved mechanical and tribological properties.