Dark-field X-ray microscopy for multiscale structural characterization.

H Simons,A King,W Pantleon,W Ludwig,F Stöhr,H F Poulsen,C Detlefs,S Schmidt,A Snigirev,I Snigireva

doi:10.1038/ncomms7098

Abstract

Many physical and mechanical properties of crystalline materials depend strongly on their internal structure, which is typically organized into grains and domains on several length scales. Here we present dark-field X-ray microscopy; a non-destructive microscopy technique for the three-dimensional mapping of orientations and stresses on lengths scales from 100 nm to 1 mm within embedded sampling volumes. The technique, which allows ‘zooming’ in and out in both direct and angular space, is demonstrated by an annealing study of plastically deformed aluminium. Facilitating the direct study of the interactions between crystalline elements is a key step towards the formulation and validation of multiscale models that account for the entire heterogeneity of a material. Furthermore, dark-field X-ray microscopy is well suited to applied topics, where the structural evolution of internal nanoscale elements (for example, positioned at interfaces) is crucial to the performance and lifetime of macro-scale devices and components thereof.

Highlights

Many physical and mechanical properties of crystalline materials depend strongly on their internal structure, which is typically organized into grains and domains on several length scales
X-ray diffraction tomography methods such as 3D X-ray Diffraction (3DXRD)[6,7,8,9,10] and Diffraction Contrast Tomography (DCT)[11,12] are capable of mapping of up to 20,000 grains in a sample, but are limited by the detector to a spatial resolution of B1 mm. 3D methods based on scanning X-ray nano-beams can provide resolutions of 100 nm, but are slow, and the mapped volume is relatively small[13,14,15]
The entire specimen is initially mapped on a coarse scale using 3DXRD or DCT and, if necessary, classical X-ray tomography

Summary

Introduction

Many physical and mechanical properties of crystalline materials depend strongly on their internal structure, which is typically organized into grains and domains on several length scales. To map the entire grain, the sample was tilted in small steps around two orthogonal axes by the angles a and b (see Fig. 1). The sample was rotated about the diffraction vector by 360°, enabling a 3D volume of the grain to be reconstructed in a manner analogous with tomography (c.f. Supplementary Note 3).

Results

Conclusion