X-ray tomography as a new tool to analyse the voids in RRP Nb3Sn wires

Scientists have developed a new tool to investigate the internal features of Nb3Sn superconducting wires, combining X-ray tomographic data acquired at beamline ID19 with an unsupervised machine-learning algorithm. The method provides new insights for enhancing wire performance.

Interest in niobium-tin (Nb3Sn) as a material for superconducting wires has recently been renewed because this material has been selected to replace niobium-titanium as the next step in accelerator magnet technology [1]. The design of these magnets relies on the availability of advanced Nb3Sn wires capable of withstanding extreme mechanical and thermal loads. The Restacked Rod Process (RRP) is considered the most promising technology to produce Nb3Sn wires at industrial scale for future accelerator magnets.

Nb3Sn is a brittle superconducting compound that cannot be drawn directly in the form of a wire. Instead, ductile precursor components are embedded in a copper matrix, drawn, brought to the final shape and then heat-treated, so that Nb3Sn forms in a reactive diffusion process. The result is a composite wire with several Nb3Sn sub-elements surrounded by copper. However, the diffusion process can lead to voids, which can play a role in the electro-mechanical and thermal behaviour of the wire. A team of scientists have developed a novel, non-destructive and non-invasive method to investigate the voids in high-performance RRP Nb3Sn superconducting wires, combining X-ray microtomography data at beamline ID19 with an unsupervised machine-learning algorithm, with a view to providing new insights into the development of these wires.

Read more on the ESRF website

Image:Fig. 1: a) 3D cross-section of a RRP Nb3Sn wire: Nb3Sn sub-elements (red), sub-element voids (light blue), copper voids (white), copper matrix (grey). b) Longitudinal cross-section of a void generated by Sn diffusion due to a leak in the sub-element. The void is highlighted in red inside the sub-element and in blue in the copper matrix, showing the sub-element failure point.

First glimpse of intricate details of Little Foot’s life

In June 2019, an international team brought the complete skull of the 3.67-million-year-old ‘Little Foot’ Australopithecus skeleton, from South Africa to the UK and achieved unprecedented imaging resolution of its bony structures and dentition in an X-ray synchrotron-based investigation at Diamond. The X-ray work is highlighted in a new paper in e-Life, published today focusing on the inner craniodental features of ‘Little Foot’. The remarkable completeness and great age of the ‘Little Foot’ skeleton makes it a crucially important specimen in human origins research and a prime candidate for exploring human evolution through high-resolution virtual analysis.

To recover the smallest possible details from a fairly large and very fragile fossil, the team decided to image the skull using synchrotron X-ray micro computed tomography at the I12 beamline at Diamond, revealing new information about human evolution and origins. This paper outlines preliminary results of the X-ray synchrotron-based investigation of the dentition and bones of the skull (i.e., cranial vault and mandible).

Read more on the Diamond website

Image: Fossil skull in Diamond’s beamline I12

Credit: Diamond Light Source

Graphite electrodes for rechargeable batteries investigated

Rechargeable graphite dual ion batteries are inexpensive and powerful.

A team of the Technical University of Berlin has investigated at the EDDI Beamline of BESSY II how the morphology of the graphite electrodes changes reversibly during cycling (operando).

The 3D X-ray tomography images combined with simultaneous diffraction now allow a precise evaluation of the processes, especially of changes in the volume of the electrodes. This can help to further optimise graphite electrodes.

Read more on the HZB website

Image: The tomogram during the charging process shows the spatially resolved changes in the graphite electrode thickness of a rechargeable aluminium ion battery in a discharged and charged state.

Credit: © HZB