Coarsening of precipitates in an advanced creep resistant 9% chromium steel—quantitative microscopy and simulations

Coarsening of MX and M23C6 particles is studied experimentally using energy filtered transmission electron microscopy (EFTEM), and with simulations obtained with the dictra software. dictra takes into account the multicomponent aspects of thermodynamics and diffusion. Both the EFTEM measurements as well as the simulations indicate very low coarsening rates for both kinds of precipitate. The influence of a change in composition on the coarsening rate is investigated by simulations. For MX the coarsening rate is almost independent of the V/Nb ratio, but highly dependent on the N-content. For M23C6 the coarsening rate decreased slightly if Mo was exchanged to some extent with W.