MICROCRACK TOUGHENING IN BRITTLE MATERIALS CONTAINING WEAK AND STRONGINTERFACES

Microcracking in brittle materials combining weak and strong interface s is analyzed. A model for the width of the process zone and the assoc iated toughening in terms of interface toughness, elastic moduli, ther mal expansion coefficients and microstructural geometry is presented. Considerable zone widths and toughening are predicted in composites wi th low interface toughness, high residual stresses and high volume fra ction of microcracks. The model is verified using toughness data obtai ned from B4C-TiB2 composites where elemental carbon segregated to B4C- TiB2 phase boundaries supplies weak interfaces. Copyright (C) 1996 Act a Metallurgica Inc.