Strengthening mechanism of SiC-particulate reinforced Sn-3.7Ag-0.9Zn lead-free solder

Mechanically mixing was adopted to prepare SiC-particulate reinforced Sn-33Ag-0.9Zn composite solders and the effects of SiC addition on the solidification behavior, melting behavior and the corresponding microhardness of air-cooled composite solders were explored. It is found that the addition of SiC particles into the Sn-3.7Ag-0.9Zn alloy melt prompts the formation of primary beta-Sn phase in the solidified structure. For the SiC particles serve as additional nucleation sites for the formation of primary beta-Sn phase, the sizes of both the beta-Sn dendrites and the intermetallic compounds (IMCs) decrease gradually with the SiC particles increasing. The hard SiC particles and refined beta-Sn dendrites and IMCs could obstruct the dislocation slipping and thus lead to a strong strengthening effect in the composite solder. (C) 2009 Elsevier B.V. All rights reserved.