Cation Interdiffusion in Polycrystalline Cubic C‐Type Yttria–Zirconia–Hafnia Solid Solutions

Cation inter diffusion in cubic C‐type solid solutions was investigated for the polycrystalline systems Y 2 O 3 —Zr x Hf 1 ‐ x‐1 O 2 and Y 2 O 3 –ZrO 2 in the small‐grain, deep‐penetration condition at 1615° to 1822°C. Lattice and grain‐boundary diffusion parameters were calculated from cation concentration distributions by using Oishi and Ichimura's grain‐boundary diffusion equation. The results indicated that Zr–Y and Zr–Hf interdiffusion coefficients decreased with an increase in Y content. The cation diffusivities were lower than anion diffusivities, and the interdiffusion parameters were lower in the C‐type cubic than in fluorite‐type cubic solid solutions. The results were compared with diffusivities in other C‐type cubic oxides.