Abstract Scope |
We demonstrate the capability of efficiently mapping the complete local strain and orientation tensor field at the sub-grain level in three dimensions inside a polycrystal, in a non-destructive way. Diffraction Contract Tomography can provide detailed 3D grain maps of moderately deformed polycrystals at the micrometre scale, utilising high-energy, monochromatic synchrotron X-rays. Using full-beam illumination and a single sample rotation enables fast and efficient scans. The ESRF source upgrade will bring scanning times of the order of minutes in in-situ experiments within reach. The highly convoluted experimental data pose a large-scale, 12-dimensional, ill-posed, non-linear reconstruction problem. A forward model and iterative solver has been developed to infer the grain shapes, sub-grain orientation and strain fields (order of 10-3 to 10-4). Furthermore, the single crystal elastic moduli are fitted from the strain data. The data acquisition and processing method, and experimental validation on a Gum metal sample under tensile load will be discussed. |