Synergistic enhancement of strength and ductility of friction stir welded 6061 aluminium alloy butt joints reinforced with Al-Cu-Fe-La quasicrystal particles

The synergistic enhancement of strength and ductility represents a key objective in the development of engineering structural materials. However, these two properties often proceed in opposing directions, making it difficult to achieve both simultaneously. In this work, a strategy for fabricating Al-Cu-Fe-La quasicrystal particle-reinforced 6061 aluminium alloy butt joints is proposed by the conjunctive use of plasma spraying and friction stir welding. Compared to conventional FSW joints without PS, the PS + FSW joints exhibit finer grains and higher geometric dislocation density in the stir zone. The optimized joint achieves a tensile strength of 177.63 ± 3.54 MPa and an elongation of 17.73 ± 0.86%, which are higher than those of the unreinforced joint, demonstrating a favorable strength-ductility synergy. The findings of this research indicate that the combined PS + FSW process effectively enhances both the strength and ductility of butt joints, while simultaneously broadening the scope of quasicrystalline alloys for industrial applications.