Toughening Behavior in Whisker‐Reinforced Ceramic Matrix Composites

TLDR

Whisker‑reinforced ceramics toughen through a bridging zone immediately behind the crack tip. Microscopy and analytical models confirm that intact whisker bridging behind the crack tip, governed by whisker size, strength, and interface properties, drives toughness in SiC‑whisker‑reinforced ceramics.

Abstract

The toughening behavior of whisker‐reinforced ceramics is analyzed in terms of a whisker bridging zone immediately behind the crack tip. This approach is consistent with microscopy observations which reveal that intact bridging whiskers exist behind the crack tip as a result of debonding of the whisker‐matrix interface. The theoretical results based on both the stress intensity and the energy change introduced by bridging whiskers reveal the dependence of toughening upon the composition and matrix, interface, and whisker properties. Furthermore, the analytical models of whisker bridging accompanied by very limited pullout accurately describe experimental observations of the toughening behavior in several SiC‐whisker‐reinforced ceramics. Such analytical descriptions also indicate that increases in whisker size and strength and modification of interface properties will result in further increases in toughness by whisker reinforcement.