| Abstract: | The microstructures of the Sn-8.55Zn-0.5Ag-xBi lead-free alloys (x = 7.5, 10, 15 and 20 wt%) after aging treatment were investigated. Microstructure of the Sn-Zn-0.5Ag alloy consists of the AgZn3 compound, the needle-like Primary-Zn phase (P-Zn), and hypo-eutectis Sn-Zn phase. With adding 7.5wt%~15wt% Bi to Sn-8.55Zn-0.5Ag lead-free alloys, the shape of the P-Zn phase becomes rod-like from needle-like. When the Bi addition added up to 20wt%, the coarse P-Zn phase becomes into the thicker needle-like one. After long-term aging at 120℃, the shape of both the P-Zn phase and Bi-rich phase distributing uniformly with ball-like in matrix.
For the XRD analysis, the Bragg peaks corresponding to Sn(200), Sn(101), Sn(211), Sn(301), Zn(002), Zn(100), Zn(101), AgZn3 (102), Bi(104), Bi(110), Bi(006), Bi(202), Bi(024), and Bi(107) are observed in the Sn-8.55Zn-0.5Ag-xBi alloys. Then, the results of XRD analysis indicate that it does not effect significantly on the crystal structure of the Sn-8.55Zn-0.5Ag-xBi alloys by aging treatment. |
