Structure of a Deformed Metallic Grain

Abstract

A NUMBER of years ago, Wood¹ suggested that the circumferential spreading of the sharp X-ray diffraction spots from annealed grains into continuous arcs along the Debye circle on deformation could be best accounted for by supposing that the grains break down into a number of fragments oriented at small angles to each other. Experiments on the deformation of polycrystalline aluminium at elevated temperatures under creep conditions have confirmed that the individual grains break down into more or less perfect crystalline elements, the degree of perfection and size of which increase with increasing temperature and decreasing strain-rate^2,3. It appears that the continuity of the Debye arcs from aluminium deformed rapidly at room temperature is due to the smallness of the fragment size. Further direct confirmation of this view has been obtained recently by a micro-beam X-ray technique⁴.