Unraveling laser-induced non-equilibrium transformation pathways in glasses
Abstract
Research Problem and Objectives: Glasses such as fused silica, soda-lime, boro-silicate glasses are widely used in military and space applications such as ballistic penetrators, aircraft and spacecraft shielding, and thus can be subjected to high-energy ballistic impacts and high-speed debris. These high energy impacts cause extreme loading conditions such as high pressure andstrain rate, which can result in material damage, deformation and failure. In order to efficiently design high-performance glasses which can withstand these extreme environments, understanding the fundamental mechanisms underlying shock loading, deformation and failure is critically needed. However, creating such high pressure, strain rate and temperature conditions in lab settingare challenging. Additionally, most of the studies have focused on characterizing the material behavior ex situ, after the shock loading cycle is complete. Thus, understanding the failure mechanism gets complicated due to different material response during initial shock, post-shock and subsequent reverberations. In this proposal, I will utilize laser-induced dynamical loading conditions to elucidate structural evolution and deformation behavior at ultrafast timescales.Technical Approach: I will combine two approaches, ultrafast laser excitation and x-ray scattering techniques, to unravel the fundamental mechanism underlying the deformation dynamics in soda-lime float glasses. Ultrafast optical lasers provide a unique way to access dynamical loading conditions in the lab environment by achieving pressure range of 10-200 GPa and strain rate of 104/s to 107/s. Time-resolved x-ray scattering techniques will be utilized to investigate laser-driven material behavior in-situ (during initial and post-shock) at femtosecondnanosecond timescales. This method will allow us to characterize structural dynamics and phase transformation, as the material is undergoing shock loading and unloading. These studies are now feasible due to development of x-ray free electron facilities which provide fast and high intensityx-rays required for such experiments. The strong background of PI in ultrafast control of electronic materials and advanced x-ray techniques will ensure successful outcome of the project.Anticipated Outcome: Proposed time-resolved x-ray studies will provide in-situ measurements of structural dynamics, nanoscale behavior and phase transition, which cannot be accessed by typically utilized optical techniques. The atomistic understanding from these studies will be critical for understanding failure mechanisms and polymorphic behavior in glasses. Unveiling the laserdriven shock loading at relevant timescales and lengthscales will add an important piece to the puzzle of transformation pathways of glasses. The microscopic understanding developed by these studies including strain behavior, shock front evolution, nucleation and growth pathways, will leadto refinement of existing theoretical models to accurately describe materials in extreme conditions. Impact on DoD capabilities: The fundamental understanding provide by these studies will enable development of high-performance glasses for shields and protections which can endure extreme shock-loading conditions. The advances in design of material structure implemented from outcomes of these studies will allow for reduced life-cycle costs and higher strength glasses.Additionally, the characterization tools developed here can be extended to understanding shock physics in other Navy-relevant materials such as polymers, composites and other glassy systems. Thus, the outcomes of our studies directly aligns to the goals of Naval R&D framework and ONRMaterials and Structures under Extreme Conditions program under Code 33 and Division 332.
Document Details
- Document Type
- DoD Grant Award
- Publication Date
- Apr 24, 2019
- Source ID
- N000141912074
Entities
People
- Roopali Kukreja
Organizations
- Office of Naval Research
- United States Navy
- University of California, Davis