This publication has been led by Stacy Moore and colleagues from the University of Bristol's Interface Analysis Centre, in collaboration with the National Nuclear Laboratory and Bristol Nano Dynamics. The HS-AFM technology developed by Dr Loren Picco and Dr Oliver Payton at the University of Bristol has won multiple awards, most notably the National Nuclear Laboratory innovation award in 2015 for the instrument’s outstanding capabilities for the characterisation of steel.

The University of Bristol HS-AFM

Stress corrosion cracking is an important failure mode in many metal systems, but it has a complicated mechanism that makes failure difficult to predict. As well as using HS-AFM, other techniques such as focussed ion beam milling and atom probe tomography were utilised to gain valuable insights into stress corrosion cracking mechanisms.

This research, funded by the National Nuclear Laboratory and EPSRC, has many  potential applications to the nuclear industry.  By being able to take in situ measurements of materials such as graphite, steels and other alloys, the cracking process can be understood in real time rather than post-event. This work shows the power of both real-time measurements and correlative microscopy. The high frame rate of the HS-AFM showed new detail on cracks propagation in Type 304 stainless steel during SCC, whilst post-cracking characterisation using focused ion beam and atom probe tomography identified subsurface voids and chemical segregation along grain boundaries, adding to the mechanistic understanding of this important failure mechanism.