Deviatoric stress measurement under uniaxial compression by a powder x-ray diffraction method

Abstract

The complete stress field in a polycrystalline sample compressed in a modified Drickamer-type apparatus was determined from x-ray diffraction data. The incident x rays, from a synchrotron source, were perpendicular to the compression axis, and the diffracted energy-dispersive signals were simultaneously determined for two directions relative to the compression axis. The two sets of d values measured by this system were analyzed by making use of a new equation derived by Singh, and the uniaxial stress component σ1−σ3 and the parameter α, which describes the stress and strain conditions across the grain boundaries of the sample, were obtained. This method was applied to NaCl and the results give the important information on the stress state and the pressure determination method under direct compression of a solid sample.