The accurate, absolute, and non-destructive measurement of residual stress fields within metallic, ceramic, and composite engineering components has been one of the major problems facing engineers for many years, and so the extension of X-ray methods to the use of neutrons represents a major advance. The technique utilizes the unique penetrating power of the neutron into most engineering materials, combined with the sensitivity of diffraction, to measure the separation of lattice planes within grains of polycrystalline engineering materials, thus providing an internal strain gauge. The strain...