Effect of different nanoparticles on microstructure, wetting and joint strength of Al–12Si–20Cu braze filler

The effect of nanoparticle additives (La₂O₃, SiC, and ZrO₂) on microstructure and brazing characteristics of Al–12Si–20Cu alloy produced by induction melting was studied. The morphology and composition of the samples was studied by x-ray diffraction (XRD), scanning electron microscopy (SEM), and energy dispersive spectroscopy (EDS) analysis. The melting point of the fillers was determined by differential thermal analysis (DTA). Filler wettability was studied in terms of spread ratio (SR) on Al 3003 substrate. The joint strength was assessed by tensile shear study in brazed lap-joints of Al 3003 sheets. The results demonstrated that addition of La₂O₃ in Al–12Si–20Cu showed best wetting (79.6%) and melting (531.2 °C), while the addition of SiC alloy showed moderate tensile shear strength (79.1 MPa) and lowest wettability (76.34%) among Al–12Si–20Cu–La₂O₃ and Al–12Si–20Cu–ZrO₂ and Al–12Si–20Cu–La₂O₃ SiC composites. The addition of ZrO₂ in Al–12Si–20Cu alloy showed moderate wetting (78.2%) and lowest tensile strength (78.3 MPa) compared to Al–12Si–20Cu–La₂O₃ and Al–12Si–20Cu–SiC. The mechanism behind the microstructural modification of Al–12Si–20Cu alloy in the presence of nanoparticle additives has also been discussed. (paper)