Abstract
Diffusion coefficients of carbon in niobium and molybdenum have been determined by the residual activity method with radioactive tracer 14C in the temperature ranges between 1168 and 1567 K for niobium and between 1271 and 1669 K for molybdenum. The temperature dependences of the diffusion coefficient of carbon in niobium and molybdenum are expressed by D/m2 s−1 = 2.2 × 10−6 exp(−152 kJ mol−1/RT) and D/m2 s−1 = 5.2 × 10−6 exp(−163 kJ mol−1/RT), respectively. Since the solubility of carbon in molybdenum is very small, the diffusion of carbon in molybdenum is strongly influenced by carbide precipitation at lower temperatures.
