Microstructure and texture formation in extruded lead sulfide (galena)

Lead sulfide (galena) of different purity and grain size was extruded throu gh a round and rectangular die at temperatures between 773 and 923 K. Globa l and local lattice preferred orientations (here referred to as textures) w ere measured by neutron and electron back-scattering diffraction. Tension l eads to a < 100 > < 111 > double fibre texture. Pure shear deformation yiel ds texture components near the ideal face-centered cubic metal brass, coppe r, Goss and cube positions. The intensity of the components depends on the purity and/or grain size. The microstructure is partially recrystallized. E lectron back-scattering diffraction indicates that in tension the < 100 > a nd in pure shear the Goss and cube components are associated with dynamic r ecrystallization. The deformation texture can be qualitatively explained by the full and relaxed constraints Taylor model using slip on {100}< 110 >, {110}< 110 > and {111}< 110 > systems. The texture formation in lead sulfid e compares well with that observed for other ionic crystals with the NaCl-s tructure as well as for face-centered cubic metals with a high stacking fau lt energy. (C) 2000 Elsevier Science Ltd. All rights reserved.