Interdiffusion in Ni-Rich, Ni-Cr-Al alloys at 1100 and 1200 °C: Part I. Diffusion paths and microstructures

TLDR: In this article, after annealing at 1100 and 1200 °C, the diffusion coefficient of Ni-Cr-Al diffusion couples was studied and the location of maxima and minima in the concentration profiles of several of the diffusion couples indicated that both cross-term diffusion coefficients for Cr and Al are positive and that DCrAl has a greater effect on the diffusion of Cr than does DA1Cr on diffusion of Al.

Abstract: Interdiffusion in Ni-rich, Ni-Cr-Al diffusion couples was studied after annealing at 1100 and 1200 °C. Recession of γ′ (Ni3Al structure), β (NiAl structure), or α (bcc) phases was also measured. Aluminum and chromium concentration profiles were measured in the γ (fcc) phase for most of the diffusion couples. The amount and location of Kirkendall porosity suggests that Al diffuses more rapidly than Cr which diffuses more rapidly than Ni in the γ phase of Ni-Cr-Al alloys. The location of maxima and minima in the concentration profiles of several of the diffusion couples indicates that both cross-term diffusion coefficients for Cr and Al are positive and that DCrAl has a greater effect on the diffusion of Cr than does DA1Cr on the diffusion of Al. The γ/γ + β phase boundary has also been determined for 1200 °C through the use of numerous γ/γ+ β diffusion couples.