Dr. Mike Short
Massachusetts Institute of Technology

Abstract

Our ability to understand how materials respond to damage is limited by our lack of understanding about the precise populations of microstructural defects created during damage processes. Nowhere is this issue more prevalent than in the field of radiation materials science, where the lack of a measurable unit of radiation damage continues to obfuscate the quantitative mechanisms responsible for the degradation of material properties under ionizing irradiation. Were the full populations of every defect in a damaged material to be known, then its material properties could be predicted with existing structure-property relations.

We propose to use stored energy fingerprints to visualize the full plethora of defects resulting from damage of any kind, particularly irradiation. We draw inspiration from a long-neglected idea from the Manhattan project, stating that radiation damage should store energy like amorphization or cold work. This idea is extended to describe all forms of microstructural damage in metals, in a measurable way which reveals the defects responsible. Using time-accelerated parallel replica dynamics simulations and ultra-fast nanocalorimetric measurements, we will directly link simulated and measured stored energy releases at the mesoscale, with atomistic understanding. This will enable a posteriori measurements of stored energy fingerprints of damaged metals, revealing the atomic configurations and quantities of defects responsible. Thus we seek to provide the full picture of defects resulting from damage, demonstrate a method to measure them, explain their evolution using atomistic simulations, and create unifying theories to predict the defect structures and resultant material properties resulting from damage in metals.

Immediate applications of this work range from reconciling the differences between ion and neutron irradiation, to predicting material property changes due to radiation damage (especially with regards to LWRS, or Light Water Reactor Sustainability), to verifying the historical usage of uranium enrichment centrifuges. We will focus on experimental results for two of these applications: (1) Using stored energy fingerprints and irradiation-induced magnetism to quantify dose to austenitic stainless steels after irradiation, and (2) Using stored energy fingerprints to determine the usage time of aluminum alloy 7075-T6 uranium enrichment centrifuges.

Biography

Michael Short joined the faculty in the Department of Nuclear Science and Engineering in July, 2013. He brings 15 years of research experience in the field of nuclear materials, microstructural characterization, and alloy development. His group’s research is a mixture of large-scale experiments, micro/nanoscale characterization, and multiphysics modeling & simulation. The main areas of Short’s research focus on 1) Non-contact, non-destructive measurement of irradiated material properties using transient grating spectroscopy (TGS) (see more), 2) Preventing the deposition of deleterious phases, such as CRUD in nuclear reactors, as fouling deposits in energy systems (see more), and 3) Quantification of radiation damage by stored energy fingerprints (see more). This last project was recently selected for an NSF CAREER award.