Influence of micro-sized Al2O3 particles on microstructure, mechanical, and wear behavior of dissimilar composite joint of AA6061/AA7075 by friction stirprocessing/welding

In the present study, the fabrication of dissimilar composite joints of AA6061/AA7075 incorporated with micro-sized Al 2 O 3 particles was carried out using friction stir welding. The impact of the dispersion pattern of different volume fractions of Al 2 O 3 micro-particles (Al 2 O 3 mp) under various combinations of tool rotational speed (RS) and traverse speed (TS) on the weld quality was studied. The composite joints were tested for tensile strength, micro-hardness, wear, and microstructural development. The results demonstrated that higher grain refinement due to dynamic recrystallization (DRX) and pinning effect of Al 2 O 3 mp considerably improved the weld quality. Higher improvements in the mechanical properties of the composite joints were also observed as the volume fraction of Al 2 O 3 mp increased. Consequently, the composite joint processed at RS of 1100 rpm, TS of 40 mm/min with 10% volume fraction of Al 2 O 3 mp exhibits the higher tensile strength of 241.35 MPa with joint efficiency of 83.80% and maximum micro-hardness of 157.5 HV. In comparison with base materials, the incorporation of Al 2 O 3 mp also improved the wear resistance of the composite joints.