During 2020 and 2021, the combination of pandemic-related closures and the ISIS long shutdown means that students may have experienced an unusually long time without being able to use ISIS for their research. Because of this, we are offering financial support for students travelling to other neutron or muon sources over this period.
One recipient of the grant was Anastasia Vrettou, a student at the University of Birmingham. Anastasia's research aims to replicate the conditions experienced by steel components during car manufacture with the aim to develop a way to test the resilience of new materials. Current standard testing only applies a stress in one direction, which is very different to what happens in real applications.
Understanding what happens to a material during manufacture is important when finding out whether more advanced, stronger, and tougher steels could survive the process without their structural integrity being compromised.
As part of her research project, Anastasia has designed a special rig that re-creates these industrial conditions. She takes samples of commercially available advanced steels and investigates their structure before and after they are put under stress. “It was an experiment like this that we would have done at ISIS," she says; “integrating mechanical testing with the neutron diffraction to study the changes to the structure. When I do experiments in the lab, I have to interrupt the stress testing to study the structure."
Her supervisor, Dr David Collins, has used ISIS multiple times in the past and is also a regular visitor to Diamond Light Source, where they had carried out complementary X-ray diffraction measurements. As they were unable to use ISIS, the team applied for, and were awarded, beamtime on the POLDI instrument at SINQ, The Swiss Spallation Neutron Source based at the Paul Scherrer Institut. They were able to use the ISIS student travel grant to support their trip.
The steel samples for this experiment were machined into shapes resembling crosses, called cruciforms, made from special grade steel produced by their industrial collaborator ThyssenKrupp that had undergone different deformation conditions. Each sample was 23 cm across and weighed over 2.5 kg, and so shipping them was a logistical challenge. “They were too big for us to take in our hand luggage!" explains Anastasia.
The samples are 10 mm thick at the edges, and then only 2 mm thick in the centre of the cross, which is the area of study. “Designing the shape of the samples was more challenging than if we had been going to ISIS," David adds; “there is no standard geometry for these tests, and we were not able to go and visit first, as we would have done if we had been doing the experiment in the UK." The image on the left shows a sample being deformed on the POLDI instrument.
But getting the samples right was only the start of the logistical challenges; “because the COVID restrictions were changing, we thought the experiment was going to be cancelled," explains Anastasia; “we actually cancelled the trip but were then able to rebook it at the last minute."
“But we made it, and the beamtime was very successful," she adds. “We are still analysing the data, but we did see that the internal structure of the steel is different if it has experienced different deformation conditions."
David adds; “Anastasia started her PhD in 2019 and the first year was very disrupted by the pandemic. The ISIS student travel grant was very welcome, as it leaves funds available for her to present her work at a conference in the future."
The scheme is still open for applications: information about how to apply can be found on the ISIS travel support scheme website.