Mixed alkali effect on Vickers hardness and cracking

• Published in: Journal of non-crystalline solids 2012-07, Vol.358 (12-13), p.1474-1479
• Main Authors: Mohajerani, A., Zwanziger, J.W.
• Format: Article
• Language: English
• Subjects: Condensed matter: structure, mechanical and thermal properties; Cross-disciplinary physics: materials science; rheology; Deformation and plasticity (including yield, ductility, and superplasticity); Exact sciences and technology; Glasses (including metallic glasses); Materials science; Mechanical and acoustical properties of condensed matter; Mechanical properties of solids; Mixed alkali effect; Physics; Radial crack; Residual stresses hardness; Specific materials; Tribology and hardness; Vickers indentation
• ISSN: 0022-3093; 1873-4812
• DOI: 10.1016/j.jnoncrysol.2012.03.029

Vickers indentation measurements were carried out on borate, silicate and aluminophosphate glasses, each series comprised of samples of different relative alkali ratios (Na/Na+Li). All the glass series exhibited nonlinear variations of hardness with relative alkali ratio, which was attributed to the reduced plastic flow of mixed alkali glasses. The mixed alkali effect was also present in the length of radial cracks although less strongly than in hardness. Using a semi-empirical model, the variations of residual stresses and fracture toughness were estimated. ► The mixed alkali effect is a general feature of Vickers hardness. ► Crack length is less affected by the mixed alkali effect. ► Residual stress shows a system dependent mixed alkali effect. ► Fracture toughness also shows a system dependent mixed alkali effect.