Coarsening Rate of M sub(23)C sub(6) and MC Particles in a High Chromium Creep Resistant Steel

The experimental coarsening rate of M sub(23)C sub(6) particles at 800 degree 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 M sub(23)C sub(6) particles in range 800-550 degree C. The calculated coarsening rates are compared to data in references. The coarsening rate of carbide particles at 800 degree 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.