I12 (JEEP) provides high-energy mono- or polychromatic X-rays for time-resolved in situ experiments. Two experimental hutches can accommodate large, medium, or small complex sample environments (chemical, mechanical and electrical processing equipment, engineering machinery, and all kinds of experimental apparatuses), which users can bring and install for their beamtime. As well as radiography and tomography techniques, JEEP offers monochromatic and dispersive diffraction techniques and Small Angle X-ray Scattering (SAXS).
| Cai B. et al. Time-resolved synchrotron tomographic quantification of deformation during indentation of an equiaxed semi-solid granular alloy. Acta Materialia 105, 338-346 (2016). |
Indentation is a well-established technique for measuring mechanical properties in solid materials. The technique involves pressing a hard indenter into the sample material, and on I12, timeresolved Micro-computed Tomography (microCT) can be used to observe the dynamic effects of this pressure on the sample’s microstructure. In this study, indentation was performed on a semisolid granular alloy with an equiaxed dendritic microstructure. The resulting microstructural effects were quantified using a novel thermo-mechanical setup combined with time-resolved microCT and digital volume correlation (DVC).
A bespoke in situ indentation rig with a resistance furnace was installed on I12 with support from the beamline team. A combination of time-resolved microCT and DVC was used to resolve the formation of deformation zones during indentation loading in 4D (three spatial dimensions plus time), offering a new perspective for micro mechanical testing of granular materials. Secondly, by indenting a semi-solid equiaxed dendritic Al–Cu alloy with a solid fraction of 72%, this study demonstrates that dilatancy is a direct response of localised deformation, leading in turn to liquid migration, solute-segregation, and solidification porosity.
The experiments not only revealed the multitude of deformation mechanisms occurring at a microstructural level (dilatancy, liquid flow, macrosegregation, shrinkage voids, and intra-granular deformation), but also allowed quantification of the evolution of the strain fields within the material. The study demonstrates the advantage of combining multiple complementary techniques to gain new insights into the mechanics of deforming semi-solid granular materials.
(a) to (d) Transverse slices at sample height of 360 μm, (e) to (h) Section view showing the distribution of liquid channel thickness at: (a) and (e) I = 0 μm; (b) and (f) I = 90 μm; (c) and (g) I = 360 μm; (d) and (h) I = 720 μm. © Acta Materialia Inc. Reused from Cai et al. under CC-BY 4.0; https://creativecommons.org/licenses/ by/4.0/.
“The scientists at JEEP go out of their way to understand the science we want to achieve, working with us to co-develop unique environmental cells that can replicate automotive manufacturing conditions. Coupled with JEEP’s time-resolved 3D imaging, this has allowed us to see inside metallic alloys to improve their properties.”
Professor Peter Lee, University of Manchester and Research Complex at Harwell
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