TOUGHENING AND STRENGTHENING BY INCLINED LIGAMENT BRIDGING

In many materials, ligaments form upon crack extension and cause tough ening by a crack bridging mechanism. Such materials include composites , layered systems and certain single crystals. Analysis of the phenome non has revealed microstructural requirements fbr optimum combinations of toughening and strengthening. The preference is for ligaments that achieve high yield strength, exhibit high toughness, small size and l arge area fraction. Ligament plasticity amends these requirements to a preference for larger ligaments: unless there are uncharted effects o f the ligament size on their yield strength and rupture strain. These effects are discussed and quantified. (C) 1997 Acta Metallurgica Inc.