Young׳s modulus, Vickers hardness and indentation fracture toughness of alumino silicate glasses

A wide range of alumino silicate glasses with different network modifier ions (Li, Mg, Na, Ca, Zn, La, Ba, Sr, and Pb) was prepared. The glasses were studied with respect to their mechanical properties: Poisson׳s ratio, Young׳s modulus, Vickers hardness and indentation fracture toughness. These properties were mostly affected by the field strength of network modifier ions. All determined properties increase with increasing field strength of the network modifier ions. The mixed modifier alumino silicate glasses with zinc and magnesium show a positive deviation from linearity with two maxima. Lanthanum containing glasses show larger values of mechanical properties for higher lanthanum concentrations. For magnesium alumino silicate glasses the mechanical properties get smaller with increasing SiO2 concentration; an effect of the magnesium concentration is not observed. Furthermore, if up to 9 mol% MgO is replaced by MgF2 the mechanical properties are not significantly affected. Compared to models predicting Young׳s moduli of all studied glass compositions, significant deviations are found.