Alignment of sample position and rotation during in situ synchrotron X‐ray micro‐diffraction experiments using a Laue cross‐correlation approach

Laue micro‐diffraction has proven to be able to reveal material properties at the sub‐grain scale for many polycrystalline materials and is now routinely available at several synchrotron facilities, providing an approach for nondestructive three‐dimensional probing of the microstructures and mechanical states of materials. However, for in situ experiments, maintaining the positioning of the sample throughout the experiment, to achieve a good alignment of the characterized volumes, is a challenging issue. The aim of the present work is to address this problem by developing an approach based on digital image correlation of focused‐beam Laue diffraction patterns. The method uses small changes in the diffraction signal as a focused X‐ray beam is scanned over a surface region to allow corrections to be made for both sample lateral movement and rotation. The method is demonstrated using a tensile deformation experiment on an Al sample with 2.5 µm average grain size. The results demonstrate an accuracy of 0.5 µm for sample position registration and a precision in sample rotation of ∼0.01°. The proposed method is fast to implement and does not require the use of additional surface markers.