Silver nanoparticle-assisted diffusion brazing of 3003 Al alloy for microchannel applications

In the current study, we investigated the effect of braze filler particle size and various processing parameters on vacuum diffusion brazing of thin foils of 3003 Al using a Ag nanoparticle (AgNPs) interlayer. All samples were brazed at 550 °C and 570 °C at heating rates of 5 °C/min and 25 °C/min under a pressure of 1 MPa. Differential scanning calorimetric results, involving 5 nm AgNPs, showed significant reduction in phase transformation temperature. Microstructures of brazed cross-sections revealed that nanoparticles aid formation of the joint at temperatures below the Al–Ag eutectic temperature of 567 °C. X-ray diffraction analysis of the interface showed the presence of δ-phase (Ag2Al) and μ-phase (Ag3Al). This was confirmed with energy dispersive spectroscopic analysis. A tensile strength of 69.7 MPa was achieved for a sample brazed at 570 °C with an interlayer of approximately 7 μm in thickness.