Interdiffusion in Binary Ni-Re Alloys

Processes of interdiffusion have been studied in the Ni-Re system. The method of electron-microprobe analysis was used to measure the interdiffusion coefficients D̃ in Ni4.4Re/Ni, Ni7Re/Ni Ni9Re/Ni, and Ni9Re/Ni4.4Re (wt %) diffusion pairs in the temperature range of 1050–1350°C. The averaged values of the preexponential factor and the activation energy for interdiffusion were found to be D 0 = 1.16 × 10−4 m2/s and Q = 317 kJ/mol, respectively. The value D 0 ∼ 10−4 m2/s is typical of substitutional alloying elements in fcc metals; the value of Q is determined to be close to that for W and is significantly higher than those that correspond to other alloying elements in nickel superalloys. No clearly pronounced concentration dependence of the coefficients of interdiffusion has been revealed at a rhenium concentration of 4.4–9 wt %.