Enhancing hardness and transmittance of high-aluminum glass-ceramics through nucleating agent content regulation

In this work, a series of high-alumina glass and glass-ceramic species were successfully prepared and the effects of nucleating agent content on glass structure, nucleation mechanism and crystallization behavior were decoded by combining experiments and molecular dynamics simulations. The results show that ZrO 2 and TiO 2 remain in the residual glass to form a strong network connection structure when the nucleating agent content is low, which is conducive to the homogeneous nucleation of LiAlSi 2 O 6 and (MgAl 2 Si 3 O 10 ) 6 crystals. However, TiO 2 and ZrO 2 would exhibit nucleation ability and induce the formation of small scale ZrO 2 -rich clusters in glass with the increase of nucleating agent content, which is more conducive to the heterogeneous nucleation of ZnAl 2 O 4 and MgAl 2 O 4 crystals. Besides, molecular dynamics simulations were used for the first time to investigate the structure and phase separation behavior of complex multi-component oxide glasses at the microscopic level, confirming the key conclusion that structural similarities between the parent glass and the final crystal play a key role in the selection of nucleation mechanisms. Furthermore, the desirable crystal phase was controlled by nucleating agent content regulation. The obtained glass-ceramic containing 5.46 mol% nucleating agent exhibited excellent overall properties, with a microhardness of 9.03 GPa and a transmittance of 81.3 % in the visible light range.