Micro structure-property relationship in high-strength MgO-Al2O3-SiO2-TiO2 glass-ceramics

An MgO-Al2O3-TiO2-SiO2 glass was exposed to various two-step heat treatments in order to produce high-strength glass-ceramics. The maximum fracture toughness of 4.3 MPa m(1/2) (accompanied by an elastic modulus of 139 GPa and a hardness of 9.5 GPa) was obtained after a two-hour pre-treatment at 800 degreesC followed by annealing at 1080 degreesC. Based on TEM imaging, energy-dispersive X-ray spectrometry, X-ray diffraction and dilatometry, an understanding of the microstructure-property relationship is developed. The high-quartz low-quartz phase transition is shown to play the key role for achieving high-strength glass-ceramics. (C) 2002 Elsevier Science B.V. All rights reserved.