Effect of micro alumina particles additions on the interfacial behavior and mechanical properties of Sn-9Zn-1Al2O3 nanoparticles on low temperature wetting and soldering of 6061 aluminum alloys

The effects of micro Al2O3 particles additions on microstructures and thermal and mechanical properties of the Sn-9Zn-1Al2O3 nanoparticles on low temperature wetting and soldering of 6061 aluminum alloys are investigated in this study. The results show that the melting temperature of the alloys firstly slightly decreases and then slightly increases with the increase in the micro Al2O3 particles concentration, while the pasty ranges of the alloys are simultaneously increased. The spreading coefficient of Sn-9Zn-1Al2O3-0.25microAl2O3 is about 13.75%, and is increased to about 41.5% of Sn-9Zn-1Al2O3-0.75microAl2O3. Both the surface diffusion, rapid adsorption and phase flow contribute to the formation of precursor film. When micro Al2O3 is added to the composite solder alloys, acicular Sn-Zn eutectic structures are smaller in size from acicular to acicular or circular spot. The strengthening mechanisms with bimodal size Al2O3 particles are on account of grain refinement and load transfer effect of bimodal sized Al2O3. The strength induced by particles is a very important part, which it can account for 21% of the total tensile strength of the solder.