Mechanical properties of molybdenum-sealing glass-ceramics

Elastic constants, thermal expansion, strength, and fracture toughness were determined for a glass-ceramic which bonds to molybdenum and matches its thermal expansion. Mechanical properties of the glass-ceramic were related to microstructure following two different crystallization treatments and moderate changes in composition. Crystallization increases the toughness and modulus of the parent glass even while the residual glass properties decline. Fracture toughness of the composite is shown to depend primarily upon properties of the separate phases; however, internal stresses are shown to decrease toughness without decreasing Young's modulus.