Preferred orientation in α-uranium

Abstract

The preferred orientation of uranium rolled in the α-range has been investigated by X-ray diffraction using a spherical specimen in the Geiger counter spectrometer. Complete figures of the principal pole distributions have been obtained without absorption correction. At low rolling temperatures, a texture is obtained having principal pole maxima corresponding to a single unit cell orientation. The (001) and (100) pole maxima lie in the plane normal to the rolling direction at 30 and 60 degrees respectively to the compression axis; the (010) pole maximum is parallel to the rolling direction. At higher rolling temperatures near the recrystallization point a duplex texture is obtained, having a common (001) pole maximum at 20 degrees to the compression axis, and having the (010) and 110) poles parallel to the rolling direction. The unit cell probability distribution has been derived using two principal pole distributions, and from this the inverse pole figures have been calculated, giving the distributions of the compression axis and of the rolling direction over the unit cell. A direct comparison of the rolling figures predicted by Calnan and Clews is obtained from the inverse pole figures. Good agreement is obtained with the figures predicted for rolling at low temperatures where deformation occurs predominantly by twinning with a small amount of slip. The rolling figures obtained at high temperatures giving the duplex texture are not in agreement with Calnan and Clews. A treatment of the deformation of α-uranium during tension, compression and rolling is described, using the glide mechanisms determined by Cahn, which is compatible with both the low- and high-temperature textures. The reorientation of the (010) axial and the duplex (010)-(110) axial textures upon recrystallization has been investigated. The (010) texture is shown to be relatively stable under recrystallization. The duplex texture undergoes reorientation to give a single component texture having the (151) pole axial. A (100) pole maximum occurs along the rolling direction which is shown to be due to overlapping of four symmetric components.