Chemical Diffusion and Phase Equilibria in the Vanadium‐Carbon System Above 1900°C

Abstract

Direct reaction of liquid vanadium and graphite resulted in the carbon‐diffusion‐controlled formation of V 2 C (below approximately 2160°C) and VC scales below 2670° C. Parabolic growth behavior for both phases was observed; the growth constant for VC was expressible as K, V”= 2.13 exp ‐ (67,000/RT) cm2/sec. The growth rate of V 2 C was lower at 2000” than at 1900°C. The chemical diffusivity of carbon in VC above 2160°C was estimated to be Dcv”= 0.26 exp ‐ (58,300/RT) cm2/sec. Several contributions to the vanadium‐carbon binary diagram are presented. The VC + C = liquid eutectic point was determined to be at C/V = 1.15 ± 0.05 at 2670°± 50°C.