The effect of temperature and deformation on the recrystallization of doped tungsten wires

The influence on the recrystallization texture and crystal size of three different dopes in tungsten wires were studied with X-ray diffraction and microscopically. Two main types of preferred orientation are produced, the [110], [320], etc., type (A), and the [531] or [421] type (B). The ratio in which those types occur and the crystal size depend with each dope on the annealing temperature and, as proved for the normal K-Si-Al dope, also on the degree of deformation of the wire. At temperatures of about 2000°C a [110]-type recrystallization texture is always found; at higher temperatures the ratio A B changes in favour of the B-type. The decrease in diameter of the wire is only of influence if it results from mechanical deformation. With diameters larger than 250 μ, type A dominates; the maximum of B-type orientations is found in (K, Si, A1) doped wires of 180 μ. This behaviour can be explained by the theory of the "damaged dope-skins" and by the relatively difficult deformation of the crystals with B-type orientation.