Three-dimensional maps of grain boundaries and the stress state of individual grains in polycrystals and powders

A fast and non-destructive method for generating three-dimensional maps of the grain boundaries in undeformed polycrystals is presented. The method re lies on tracking of micro-focused high-energy X-rays. It is verified by com paring an electron microscopy map of the orientations on the 2.5 x 2.5 mm s urface of an aluminium polycrystal with tracking data produced at the 3DXRD microscope at the European Synchrotron Radiation Facility. The average dif ference in grain boundary position between the two techniques is 26 mum, co mparable with the spatial resolution of the 3DXRD microscope. As another ex tension of the tracking concept, algorithms for determining the stress stat e of the individual grains are derived. As a case study, 3DXRD results are presented for the tensile deformation of a copper specimen. The strain tens or for one embedded grain is determined as a function of load. The accuracy on the strain is Delta epsilon similar or equal to 10(-4).