Cermets having transformation-toughening properties and method of heat- treating to improve such properties

摘要

A powder metallurgy composite material comprising grains of a relatively hard material and a binder for binding the grains together, the binder being metastable and transformable at ambient temperature by the application of mechanical force from an initial state in which the major phase of the binder is austentic to a second state in which the major phase of the binder is martensitic, whereby the binder, while undergoing this transformation, absorbs mechanical energy applied to the composite material for increasing its fracture toughness and resistance to fatigue crack nucleation and propagation. Also disclosed is a method of heat-treating the composite materials to improve their transformation- toughening characteristics. A heat-treatable composite material having such improved transformation-toughening properties is also disclosed.