Microstructural development on crystallizing hot-pressed pellets of cordierite melt-derived glass containing B2O3 and P2O5

Comparing the crystallization mechanism of stoichiometric and B2O3 and P2O5 containing glass reveals that the additives extend the gap between the glass transition and crystallization temperatures and suppress formation of μ cordierite while promoting direct crystallization of α cordierite. Detailed TEM analysis of nucleation and growth of crystals in hot-pressed pellets of B2O3/P2O5-containing glass particles shows that nucleation occurs on unidentified heterogeneous nuclei at the sites of the previous particle surfaces. Growth of α cordierite with a cellular morphology or μ cordierite with a dendritic morphology is most likely controlled by the glass composition directly ahead of the growth front