Toughening by Stress-Induced Microcracking in Two-Phase Ceramics

Two glass/alumina composites were examined as potential systems for stress-induced microcrack toughening. A borosilicate glass/alumina material having a thermal mismatch strain of approximately 0.8% demonstrated toughness up to twice that of an aluminosilicate glass/alumina composite and other reported glass/alumina composites. High-sensitivity density measurements confirmed a density reduction on application of a stress in the borosilicate glass/alumina system, providing indirect evidence for stress-induced microcracking.     

Computer Simulation of the Elastic and Fracture Behavior of Sodium Chloride Crystal

Molecular statics calculations of mechanical properties have been carried out for NaCI using the Born–Mayer–Huggins pair potential and periodic boundary conditions. Three truncation techniques are utilized. For each, calculations have been performed as a function of the truncation distance. The stress–strain curve, the fracture strength, and the fracture strain are found to be much more sensitive to the truncation technique and to variations in the truncation distance than other properties such as the elastic constants, the cohesive energy, or the lattice parameter.