The plastic behaviour of natural sphalerite single crystals between 473 and 873 K

Abstract

Natural single crystals of sphalerite were strained by creep or by constant-strain-rate compression tests with [110] parallel to the compression axis and between 473 and 873 K. Transmission electron microscopy observations showed that the dislocation structure was mainly formed with 60° and edge dipoles and multipoles. The dislocations were widely dissociated and the stacking fault energy was determined from dark-field weak-beam images. The variations in the flow stress as a function of temperature revealed that the plastic deformation was thermally activated. Differential creep and stress relaxation tests allowed computation of the apparent activation area and enthalpy. The experimental results showed that two domains could be defined: below 600 and above 640 K. The possible deformation mechanisms are discussed in view of the experimental results.