CAREER:Quantifying Radiation Damage in Metals with Wigner Energy Spectral Fingerprints

Massachusetts Institute Of Technology, Cambridge MA

Investigators

Abstract

Non-Technical The concept of "damage" to a metal remains difficult to quantify. Metals are among our most important structural materials, providing the backbone to everything from buildings, to bridges, to nuclear reactors. If we had a universal way to measure damage, we would be able to better predict when metals would fail, measure their degradation during service, and design new metals to be both longer-lasting and more economical. The use of stored energy fingerprints is proposed as a way to quantify damage to metals from any damaging process. We focus on radiation damage as an ideal way to make all the types of defects found in metals. A two-pronged experimental and simulation approach will be used to quantify and understand these stored energy fingerprints, relating them directly to the defects created by damage. Immediate applications of this work range from reconciling the differences between ion and neutron irradiation, to predicting material property changes due to radiation damage, to verifying the historical usage of uranium enrichment centrifuges. This enhanced understanding will also be the key to lowering the barriers to its study, creating completely new opportunities for both hands-on instruction and inclusion of more underrepresented minority (URM) students into what is currently one of the least diverse fields in STEM. Technical 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 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.