Vanadium self-diffusion in pure vanadium and in dilute vanadium-iron and vanadium-tantalum alloys

Abstract

Abstract Measurements of vanadium self-diffusion have been made over the temperature range 1050–1874°C. The solute enhancement factor b for vanadium self-diffusion has also been measured in dilute vanadium-iron and vanadium-tantalum alloys. These results, together with the authors' previously published results on iron impurity diffusion in vanadium, are analysed using the vacancy models of Le Claire (1970) and Jones and Le Claire (1972) to calculate the isotope effect parameters fi , which are then compared with the measured values of fiδK of Coleman. Wert and Peart (1968). Our results confirm the existence of three regimes: (1) free single vacancy migration between 1200 and 1550°C, (2) divacancy contribution at higher temperatures and (3) acceleration of diffusion due to other defects such as dislocations, subgrain boundaries and/or vacancy-interstitial impurity pairs at low temperatures.