Tuning the hardness and crack resistance through liquid-liquid phase separation in an aluminosilicate glass

Here, spinodal decomposition is used as a strategy to enhance the mechanical properties of the 30Al₂O₃·70SiO₂ glass. The melt-quenched 30Al₂O₃·70SiO₂ glass exhibited a liquid-liquid phase separation with an interconnected snake-like nano-structure. Through further heat treatment at 850 °C for different durations of up to 40 hours, we observed a continuous increase of up to about 0.90 GPa in hardness (H_v) together with a drop in the slope for H_v rise at 4 hours. However, the crack resistance (C_R) achieved a maximum value of 13.6 N when the heat treatment time was 2 hours. Detailed calorimetric, morphological and compositional analyses were conducted to elucidate the effect of tuning the thermal treatment time on hardness and crack resistance. These findings pave the way to utilize the spinodal phase-separated phenomena to enhance the mechanical properties of glasses.