Low-temperature diffusion of carbon in iron measured by SIMS technique

Depth profiling mode of MiniSIMS device was applied to diffusion measurement. As an example, carbon diffusion in BCC iron was studied. There are sparse experimental diffusion data at temperatures below the eutectic horizontal (996 K). This is caused by the fact that direct measurement of carbon diffusion coefficient in ferrite at low temperatures is complicated by very low solubility of carbon. For practical purposes, the extrapolation of high-temperature data to low temperature region is usually used for estimation of diffusioncontrolled kinetics in ferrite alloys. Present work has shown that the SIMS technique can be applied to the study of carbon diffusivity in iron. Special technique was developed, which avoids radio-tracer measurements with C-14. Obtained results are lower than the extrapolated values, which may be due to limited solubility of carbon in iron