Small angle scattering from cold-worked and fatigued metals

Abstract

Abstract Experiments have been made on the small angle scattering of x-rays from polycrystalline copper and single grains of aluminium deformed by cold work or fatigued by pulsating tension. The results confirm in a direct and conclusive way that almost all of the scattering is due to double Bragg reflections as proposed by Beeman et al.No surface scattering has been observed. Double Bragg reflections have been eliminated in small angle scattering experiments using cold neutrons: the results indicate the magnitude of the scattering from defects in the volume of the metal. The magnitude of the effect is consistent with scattering from dislocations. There was no observable effect from fatigued metals. Hence there is no direct evidence for the existence of cavities in metals as a result of small angle scattering experiments with either x-rays or neutrons.