A Combinatorial Study of Diffusion Path, Mechanical Strength, and Kinetic Assessment of γ-FeNiCu Alloys at 1000 °C

A single-phase Fe–Ni–Cu diffusion couple was studied at 1000 °C in γ (FCC)-phase region. The diffusion path of the couple was represented by empirical method based on relative concentration variable and diffusion path slope, as originally proposed by Dayananda and Kim. The empirical representation closely matches with the experimental diffusion path with a minor deviation at higher concentrations of Ni. Quantitatively, the maximum deviation on predicted diffusion path was found to be 0.05 and 0.13 on the two sides of the cross-over composition \({(Y}_{c})\) ${(Y}_c)$ . To determine the mechanical strength along the diffusion zone, nanoindentation has been performed and it is observed that the nano-hardness increases with increasing solute contents in Ni. The average effective interdiffusion coefficients ( \({\widetilde{D}}_{i,L}\) ${\tilde{D}}_{i,L}$ and \({\widetilde{D}}_{i,R}\) ${\tilde{D}}_{i,R}$ ) vary significantly, indicating that the interdiffusivity is a strong function of composition in the diffusion zone. The total effective penetration depth ( \(\overline{x }\) $\overline{x}$ ) was found to be lowest for Cu and highest for Fe.