Small Angle Intensities from Double Bragg Reflections in Cold?Worked Metals

Abstract

The small angle intensity from a cold-worked polygrained metal is treated in terms of double Bragg reflections. It is assumed that cold work breaks up the original grains into subgrains with varying orientations, such that a first reflection in one subgrain can be followed by a second reflection in another subgrain of the original grain. For an initial sample which is polygrained with random orientation, the small angle intensity resulting from cold work is given in absolute units in terms of two parameters; an average initial grain size G, and a subgrain correlation function p( ep) giving the distribution in orientation of subgrains with respect to any average subgrain of the original grain. Under favourable conditions, both of these quantities can be obtained from the small angle intensity curve. For polygrained metals, small angle scattering is a useful tool -for obtaining the subgrain correlation function peep), a quantity not obtainable from the usual high angle measurements.