Capturing metal failure on film

Materials World magazine
,
13 Oct 2020

By combining laser light, an ultra-fast camera and a theoretical model, researchers are exploring what happens to metal alloys when they are stretched to breaking point.

The team from Aalto University, Finland, is focused on solving the Portevin-Le Chatelier (PLC) effect – when bands of deformation in a material move as it stretches. This causes unpredictable deformation – as seen in materials such as aluminium alloys often used in cars and aircraft. The researchers want to improve understanding of how the bands move to better predict materials deformation.

Once the team had gathered data using the high-speed cameras and laser light for illumination, they applied an evolved version of the ABBM model – used for the behaviour of magnets – which they discovered could successfully predict the behaviour of materials as they deform.

‘The art of the theory of this work was realising which parameters of the material aligned with the parameters in an evolved version of the ABBM model,’ says Professor Mikko Alava, Leader of the research group at Aalto.

Tero Mäkinen, Doctoral Candidate at the University, adds, ‘Until now the time resolution of the experiments has not been sufficient for comparison with this type of model. The movement of the deformation bands has been studied previously, particularly in the material science community, but one really needs to see the fine detail to be able to show that the bands behave – in some sense – similarly to magnets.’

The team believes that the model can be applied to the PLC effect in aluminium alloys and will further test a wider range of metal alloys.