Enhancement of thermal stability by microstructural refinement in nanocomposite materials

The enhancement of thermal stability in nanocrystalline-amorphous (NC–a) materials was investigated by a modified Monte Carlo Potts method. The thermal stability, including the grain size stability and amorphous distribution stability, was found to be controlled by the amorphous fraction f and the energy ratio (Jgb/Jint) of the NC–NC grain boundary energy to the NC–a interfacial energy. The best thermal stability for temperatures up to 1550 K was observed with f = 0.279 and Jgb/Jint = 12, where finer grains are surrounded by thin and coherent NC–a boundaries.