New Microscopes to Visualize 3D Dynamics in Subsurface Defects New Microscopes to Visualize 3D Dynamics in Subsurface Defects 

Materials strengthen or shatter as they respond to their surroundings via multiscale dynamics from defects at the atomic scale. For centuries, scientists and engineers have struggled to connect a material’s fundamental properties directly to its structure. Today, we understand that dislocations pattern into 3D hierarchical networks that dictate the microstructure, setting the properties and dynamics of the system. However, our understanding of these dynamics is limited by a lack of experiments to directly resolve how dislocation pattern deep beneath a material’s surface.

My group has developed time-resolved dark-field X-ray microscopy (DFXM) to directly image dislocations and their collective dynamics in real-time, hundreds of micrometers beneath any surface. In this talk, will describe the optical, theory, and analytical frameworks that we developed to image and interpret these subsurface dynamics from ms-fs timescales. Using this new framework, I will then present results showing a new view of how dislocation boundaries evolve in single-crystal aluminum at temperatures that have long been inaccessible to theory and experiments. Zooming in on the dislocations that comprise a tilt boundary, I will show how the stochastic motion of the boundary dislocations over 10 minutes reveal how it loses its inherent stability at 0.99 Tm. This new capability opens new opportunities to establish the fundamental science underlying our understanding and control of defects, for applications in sustainable manufacturing – including new work exploring sustainable ironmaking and metal 3D printing.

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