Interdiffusion and atomic mobility in FCC Ag–Cu–Ni alloys

In the present work, the diffusion behavior of the Ag–Cu–Ni alloys was comprehensively studied for the first time. Twelve solid-solid diffusion couples were prepared and annealed at 1023, 1123, and 1223K, respectively. Based on the measured composition-distance profiles, the interdiffusion coefficients in FCC Ag–Cu–Ni alloys at different temperatures were then calculated by both the Matano-Kirkaldy (MK) and numerical inversion (NI) methods. The atomic mobilities of the Ag–Cu–Ni alloys were also optimized. The results indicate that the model-predicted diffusion behavior shows reasonable agreement with the experimental data, validating the reliability of the two versions of atomic mobility obtained in this work and demonstrating the accuracy and efficiency of the NI method. Ag diffuses faster than Ni in the Cu matrix alloy. The pre-exponential factor D_0Ag and the activation energy Q_AgAg^Cu show a slight change with the Ag, but significantly increase with the Ni. The variation of the pre-exponential factor D_0Ni and the activation energy Q_NiNi^Cu with the concentration of Ag and Ni were presented with a 3-D planes and discussed in detail. The accurate diffusivities and atomic mobilities of FCC Ag–Cu–Ni alloys obtained in this work will provide crucial input for the development and design of multi-component low-Ag brazing filler metals.