Compression behaviour of elastically anisotropic polycrystals using energy-dispersive X-ray diffraction

The compression behaviour of a foil of Cu3Au in a pressure medium of NaCl has been studied by energy-dispersive X-ray diffraction in a diamond-anvil cell. Evidence from stress analysis and peak broadening of the foil (the most extreme example of a non-ideal powder) throws light on the compression of powders under non-hydrostatic conditions. A complete pressure cycle, including re-pressurization after pressure release, shows that significant plastic deformation takes place which results in large deviations from a (hydrostatic) equation of state. The origin of the deformations is traced to shear stresses transmitted to the sample through the pressure medium.