Influence of TiO2 nanoparticles addition on the microstructural and mechanical properties of Sn0.7Cu nano-composite solder

Composites of SC solder reinforced with 0,0.25,0.5 and 1 wt.% of TiO2 nanoparticles were fabricated using a mechanical technique. With increased addition of TiO2 nanoparticles, the SC nano-composite solder was found to have a slightly lower melting temperature. The addition of TiO2 nanoparticles can also effectively refine the microstructure as so beta-Sn and Cu6Sn5, and increase the percentage of eutectic area. The mechanical properties (microhardness, 0.2% YS and UTS) increase with the increasing presence of reinforcement, far exceeding the strength of the eutectic SC solder. The yield strength improvement was attributed to (i) the Hall-Petch effect due to beta-Sn grain size refinement. (ii) Orowan strengthening, (iii) generation of geometrically necessary dislocations to accommodate CTE mismatch between the matrix and the second phase (Cu6Sn5 and TiO2), and (iv) the load-bearing effects due to the presence of nano-sized reinforcements. (c) 2012 Elsevier B.V. All rights reserved.