Interdiffusivity in the Ir-rich solid solutions of Ir-X (X = Pt, Rh and Re) binary alloys was investigated in the temperature range of 2073-2373 K. The interdiffusion coefficients within the solute concentration range up to 10 at.% were evaluated through conventional diffusion-couple experiments. The composition dependence of the interdiffusion coefficient was negligible in the Ir-Rh and Ir-Re solid solutions. On the other hand, some composition dependence was evident in the interdiffusion coefficient of the Ir-Pt solid solution, which increased with increasing Pt content. In comparison with the tracer self-diffusivity of pure Ir, the interdiffusivity in the Ir-Rh and Ir-Pt solid solutions was higher, but that in Ir-Re was lower within the temperature range studied.
- Boltzmann-Matano analysis
- diffusivity measurements
- electron probe microanalysis (EPMA)