Diffusion studies in Hf-Mo, Zr-Mo, Cr-Nb, Cr-Ta and Th-Re systems above 1900 K

The paper describes an experimental procedure for carrying out high temperature diffusion studies involving liquid phase. The method has been successfully demonstrated for studying diffusion in binary refractory alloys in Hf-Mo, Zr-Mo, Cr-Nb, Cr-Ta and Th-Re systems at temperatures between 1930 K and 2360 K. The present method provides diffusion data for both solid solutions and the intermediate phases present in each of these systems. The paper reports the tracer diffusion coefficients for Hf and Zr in Mo and Cr in Nh and Ta at infinite dilution without using radio tracers. The values of interdiffusion coefficients using both concentration gradient and chemical potential gradient as the driving force have been determined. The advantages in using interdiffusion coefficient with chemical potential gradient as the driving force particularly in the intermediate phases are discussed. (C) 2000 Elsevier Science S.A. All rights reserved.