Coarsening Rate of M23C6 and MC Particles in a High Chromium Creep Resistant Steel

The experimental coarsening rate of M23C6 particles at 800°C was about three times greater than that calculated from the slightly modified Lifshitz–Slyozov–Wagner equation. Applying a simplified relation, the coarsening rate was deduced for M23C6 particles in range 800–550°C. The calculated coarsening rates are compared to data in references. The coarsening rate of carbide particles at 800°C is determined experimentally and calculated. By substituting in LSW equation molar carbide content with atom content of chromium in solid solution, the difference of both rates is lower by 2 orders of magnitude. It is confirmed that the smaller difference is due to the shorter diffusion time for chromium atoms from solid solution than from decomposing carbide particles.