| Differential scanning calorimetry, X-ray diffraction, and scanning electron microscopy et al. have been employed to study the melting point, wettability, and microstructure of Ag-49Cu-xGa (x=5, 7, 10) brazing material. Thermodynamic calculations and analysis are also carried out using the Miedema model and the Toop model. The results indicate that, the Ga element in the brazing material is completely dissolved in the Ag matrix and Cu matrix, and due to the lower chemical potential of Ga element in the Cu rich phase, Ga element tends to be dissolved more in the Cu rich phase. With the increase of Ga content, both the solidus and liquidus of the alloy decrease, but the temperature difference between them increases. At 810 ℃, the spreading area of AgCuGa solder on the surface of oxygen free copper and nickel sheets increases, the wetting angle decreases, and the spreading coefficient increases with the increase of Ga content, so the wettability is improved. Ag-49Cu-10Ga has the best wettability on oxygen free copper and nickel sheets. After the wettability experiment, the edge of the brazing material is dendritic structure, and the proportion of coarse and approximately circular Cu rich phases in the central area of the brazing material is relatively large. With the increase of Ga content, the proportion of Cu rich phases in the central area of the brazing material and the average ar0ea of a single Cu rich phase show an increasing trend. |
