Microstructure and mechanical properties of Sn-9Zn-xAl2O3 nanoparticles (x=0-1) lead-free solder alloy: First-principles calculation and experimental research

This paper studies microstructure and mechanical properties of Sn-9Zn-x Al2O3 nanoparticles (x=0-1) lead-free solder alloy. The interface structure, interface energy and electronic properties of Al2O3/Sn9Zn interface are investigated by first-principle calculation. On the experimental part, in comparison with the plain Sn-9Zn solder, the Al2O3 nanoparticles incorporated into the solder matrix can inhibit the growth of coarse dendrite Sn-Zn eutectic structure and refine grains of the composite solders during the solidification process of the alloys. Moreover, the microhardness and average tensile strength of the solders with addition of Al2O3 nanoparticles increased with the increasing weight percentages of Al2O3 nanoparticles. These improved mechanical properties can be attributed to the microstructure developments and the dispersed Al2O3 nanoparticles.