Diffusion of vanadium in the Fe–V system

The diffusion coefficients D of vanadium in Fe–V solid solutions in the concentration interval 0 to 90 wt% V and in the temperature range 839 to 1320 °C are determined by the residual activity method using the isotope V-48. The measured residual activity values are evaluated by the least squares method on a ZPA-600 computer. All the D-values satisfy the Arrhenius relation enabling the calculation of the diffusion characteristics D0 and ΔH. Analogously to the f.c.c. solid solutions an attempt is made to develop unique equations describing the temperature and concentration dependences of the V-diffusion in Fe–V solid solutions. The analysis of present results shows that at a given temperature the variation of In D(cV) is linear in the primary Fe–V solid solutions (1.6 to 28% V) and parabolic in the vanadium rich solutions (65 to 100% V). In both the cases the diffusivity of V decreases with the increasing vanadium concentration cV. The peaks in the In D0(cV) and ΔH(cV) variations found at 24% V are interpreted in terms of the Fe3V ordered structure. Similar peaks occurring at 75% V recall the results given by Šiňjajev in the Fe–Cr-system. An unambiguous interpretation of these peaks is not found.