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Wednesday, January 02

Atomistic Modeling of Defects Evolution in
Advanced Materials for Energy Applications

Yue Fan, Massachusetts Institute of Technology, Cambridge
Materials Science and Techology Division Seminar
11:00 AM — 12:00 PM, Building 4500-S, Room A-177
Contact: Gene Ice (icege@ornl.gov), 865.574.4065

Abstract

The evolution of irradiated defects and their interaction with dislocations are considered one critical factor to the mechanical properties of nuclear structural materials, and have been widely studied by atomistic simulations. However, there is still a formidable challenge to computationally model and predict microstructural evolution over long times using conventional computational methods while retaining the atomistic fundamentals.

By developing an innovative computational technique, the Autonomous Basin Climbing (ABC) method, we are able to acquire a fundamental and predictive understanding of the long time scale evolution in irradiated materials. We demonstrate that the interaction between dislocation and obstacle can have two different mechanisms at different time scales: under high strain rate condition, the dislocation simply passes through the obstacle and defects get recovered; under low strain rate condition, however, the obstacle is absorbed by the dislocation associated with a jog formation. Our derived interaction mechanism map can well address the controversy between experiments and previous simulations. To generalize the understanding, we further proposed a theoretical framework to analytically demonstrate how the surrounding environments, e.g. applied strain rate, temperature, etc., can affect the metals strength.

The combination between simulation, theory derivation, and the benchmark against experiments streamlines a universal workflow from atomistic modeling to science and engineering projects. The prospective application of this framework to other important system, e.g. the glass materials, is also proposed.