High-resolution X-ray imaging of the mesoscale during dynamic loading
The capability of single-shot phase contrast imaging to capture the evolution of internal damage produced in a sample subjected to shock loading will be developed. A portable mesoscale gas gun, recently designed by the team at the Institute of Shock Physics, Imperial College, will be transported to the I12 high-energy beamline at the Diamond Light Source, and used to drive compression waves into solid and porous metal targets. X-ray pulses of up to 150 keV will be used to perform ultrafast phase contrast imaging to capture a snapshot of the internal microstructure during the deformation process. Time-resolved experiments on a variety of materials will result in some of the first glimpses of internal void nucleation in solids, and microjetting/vorticity in porous metals, thereby demonstrating a new diagnostic capability for the high-rate community.
The bulk mechanical response of materials subjected to dynamic loading has its origins in physical processes occurring at the underlying mesoscale. Standard time-resolved diagnostics, however, are almost exclusively based upon visible radiation, and thus suffer limited penetration into high-Z materials. Consequently, knowledge of dynamic material behaviour is based upon surface measurements, which are insufficient to reveal the early stages of damage such as void nucleation, twinning, microkinetic flow, or local phase transitions. The potential for revealing these finer processes lies in the use of synchrotron X-rays, as recently demonstrated at the Advanced Photon Source this past year. Using a small impact launcher, Luo et al. successfully performed single-shot phase contrast imaging to resolve internal features of deformation at the microscale [1-3]. Their work has since featured prominently at meetings on high-rate science and new experimental capabilities (i.e., SCCM1, APS2) and represents a pivotal development for the dynamic phenomena community. Such a capability will be brought to the UK, delivering a new tool to the high-rate and extreme conditions community, allowing subsurface imaging and eventually diffraction of transient states.
: S. N. Luo, B. J. Jensen, D. E. Hooks, K. Fezzaa, K. J. Ramos, J. D. Yeager, K. Kwiatkowski, and T. Shimada,
Review of Scientific Instruments 83, 073903 (2012).
: J. D. Yeager, S. N. Luo, B. J. Jensen, K. Fezzaa, D. S. Montgomery, and D. E. Hooks, Composites Part A 43,
: B. J. Jensen, S. N. Luo, D. E. Hooks, K. Fezzaa, K. J. Ramos, J. D. Yeager, K. Kwiatkowski, T. Shimada, and
D. M. Dattelbaum, AIP Advances 2, 012170 (2012)