Capturing Radiation-induced Microstructure Evolution In Situ Through Direct Property Monitoring

Cody Dennett, Massachusetts Institute of Technology

Photo of Cody Dennett

Advanced materials development for nuclear systems is a time- and resource-intensive process relying on many iterations of material exposure and destructive testing to determine performance. Techniques such as <em>in situ</em> TEM can provide local structural information during irradiation, but no current methods are able to continuously monitor bulk thermal and mechanical properties. A method with this ability would be transformational in pinpointing the onset of emergent irradiation-induced microstructural evolution - such as the transition from incubation to steady-state void swelling - on a much shorter time scale that traditional methods. For this purpose, we have adapted a time-resolved, non-destructive and non-contact photoacoustic technique known as transient grating spectroscopy (TGS). This method is able to extract elastic and thermal transport properties from a surface on the same length scale to which ion beams can impose damage. Following <em>ex situ</em> validation, we developed an <em>in situ</em> TGS beamline experiment for concurrent ion beam irradiation and property monitoring on the 6 MV tandem accelerator at the Ion Beam Laboratory at Sandia National Laboratories. This experiment is used to study radiation-induced evolution in metals and alloys at orders-of-magnitude finer resolution in applied dose than is possible with traditional methods. We are now able to provide the type of rapid, engineering-relevant data necessary to speed the innovation cycle in nuclear material development. Moving forward, these methods will be used as screening and down-selection tools to expedite the design and testing process for advanced nuclear materials.

Abstract Author(s): Cody A. Dennett, Khalid Hattar, Michael P. Short