Neutron Strain Measurement of Internal Strain in Metal and Ceramic Matrix Composites

Stresses can arise in a composite on a range of distance scales and can have many origins. Differences in thermal expansion and elastic constants, the plastic deformation of one phase relative to another, a structural transformation of one phase, all lead to internal stresses between the phases and have important consequences for the performance of the composite. As a result, understanding the evolution and interaction between these stresses is pivotal to an intelligent development of this important class of engineering materials. Neutron diffraction has grown to be an invaluable tool in this respect. In this review the fundamental basis of the technique is laid out before presenting an examination of the state of the art. This latter objective is achieved through a series of examples including work on metal-fibre, ceramic monofilament, particle, and whisker reinforced metal, intermetallic and ceramic composites, as well as cemented carbides and laminated materials.