Wetting kinetics of the AgCuTi filler metal on pure molybdenum substrate

Spreading of the AgCuTi filler metal over a pure molybdenum substrate under a high-purity argon atmosphere was studied at elevated temperatures, within the range of 1283~1373K. Real-time in situ observations and quantitative measurements assisted by hot-stage microscopy were used to analyze the kinetics of the triple-line movement. The state of the interface between the substrate and the resolidified alloy and in the neighborhood of the triple line was considered. The empirical data indicate that wetting of AgCuTi alloy on the pure molybdenum substrate features a similar trend of the triple-line kinetics. The triple-line equivalent radius of the front during spreading increases initially, with a large spreading rate, and subsequently changes gradually the rate approaching to an asymptotic value. Kinetics of the triple-line movement throughout the spreading process shows that the wetting follows the power law, Rⁿ~t, n~8. During spreading, Ag-based solid solution, AgCu eutectic phase, and CuTi binary phase were formed along the interface within the joint zone, hence the spreading evolves under weak reactive conditions.