Nanox: a miniature mechanical stress rig designed for near-field X-ray diffraction imaging techniques

N Gueninchault,H Proudhon,W Ludwig

doi:10.1107/s1600577516013850

Abstract

Multi-modal characterization of polycrystalline materials by combined use of three-dimensional (3D) X-ray diffraction and imaging techniques may be considered as the 3D equivalent of surface studies in the electron microscope combining diffraction and other imaging modalities. Since acquisition times at synchrotron sources are nowadays compatible with four-dimensional (time lapse) studies, suitable mechanical testing devices are needed which enable switching between these different imaging modalities over the course of a mechanical test. Here a specifically designed tensile device, fulfilling severe space constraints and permitting to switch between X-ray (holo)tomography, diffraction contrast tomography and topotomography, is presented. As a proof of concept the 3D characterization of an Al-Li alloy multicrystal by means of diffraction contrast tomography is presented, followed by repeated topotomography characterization of one selected grain at increasing levels of deformation. Signatures of slip bands and sudden lattice rotations inside the grain have been shown by means of in situ topography carried out during the load ramps, and diffraction spot peak broadening has been monitored throughout the experiment.

Highlights

After more than ten years of development, three-dimensional (3D) X-ray diffraction (3DXRD) techniques routinely provide orientation maps of polycrystalline materials
The majority of studies involving 3D grain mapping coupled with repeated observations of samples as they evolve as a function of strain (King et al, 2008) or load cycles (Herbig et al, 2011; King et al, 2011) were conducted in such a way that the grain microstructure of the sample was
In this paper we propose a design fully compatible with the 3DXRD microscope at the European Synchrotron Radiation Facility (ESRF) and fulfilling the abovementioned requirements for four-dimensional observations including phase contrast tomography, diffraction contrast tomography and topotomography imaging modalities

Summary

Introduction

After more than ten years of development, three-dimensional (3D) X-ray diffraction (3DXRD) techniques routinely provide orientation maps of polycrystalline materials. Employing two-dimensional diffraction detectors positioned some hundreds of millimeters behind the sample, they usually provide ample space for sample environment like stress rigs or furnaces and have been used for time-lapse studies of grain rotations (Margulies et al, 2001), evolution of strain tensors during tensile loading (Martins et al, 2004; Oddershede et al, 2011) or for the observation of grain coarsening processes (Wu & Jensen, 2012). Near-field diffraction imaging techniques, on the other hand, employ high-resolution X-ray imaging detector systems and provide access to spatially resolved orientation maps and 3D grain morphologies. The majority of studies involving 3D grain mapping coupled with repeated observations of samples as they evolve as a function of strain (King et al, 2008) or load cycles (Herbig et al, 2011; King et al, 2011) were conducted in such a way that the grain microstructure of the sample was

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