Experimental measurements of the interdiffusivities in fcc Co–rich Co–Ti, Co–W and Co–Ti–W systems

Abstract

Utilizing 8 bulk single–phase diffusion couples together with the electron probe microanalysis technique, the composition–distance profiles of fcc binary Co–Ti and Co–W systems as well as ternary Co–Ti–W system at 1373K were first measured. The measured composition profiles for Co–rich Co–Ti, Co–W and Co–Ti–W systems at 1373K were then adopted to evaluate the corresponding binary and ternary interdiffusivities by using the newly proposed pragmatic numerical inverse method. The comprehensive comparisons between various model–predicted diffusion properties based on the evaluated interdiffusivities due to the pragmatic numerical inverse method, including composition profiles, interdiffusion fluxes and diffusion paths, and the experimental data were conducted to validate their reliability. Moreover, the presently obtained binary and ternary interdiffusivities by the numerical inverse method were further validated by the literature data and the calculated results by using the traditional Sauer–Freise method and Matano–Kirkaldy method.