SOW for the project: acoustoplasticity is a class of phenomenon where softening of metallic structures is induced by quasi-static and dynamic elastic waves. They have been proven to be useful in several manufacturing applications including ultrasonic extrusion, welding, wire-bonding, flip-chip bond, wire drawing, and so on. Despite the large body of work on the use of this phenomenon for several novel applications, there is also a lack of fundamental understanding of the mechanics behind acoustoplasticity. This can be attributed to three main reasons: (1) Acoustic excitation occurs in the macroscale, but its effects can be spread over 6 orders of magnitude in the spatio-temporal scale; (2) Single-scale models/techniques smear out many characteristic length scales and cannot address the full complexity of it; (3) probing the acoustic-affected dislocation plasticity is non-trivial due to the fast time scale of the events. Without a quantitative understanding of acoustoplasticity, there will be no adequate scientific basis for wider application of this phenomenon. The goal of this proposal is to develop a bottom-up understanding of acoustoplasticity through an integrated multiscale computational and experimental analysis.

Certain solid oxides, such as SrTiO3/MgO, contain defects like dislocations, grain boundaries (GBs), phase boundaries (PBs), and can be plastically deformed without cracking. These defects carry high local stresses and can severely deform the materials locally. This may be utilized to enhance the ion mobility and in turn, the material's ionic conductivity, but is at a "trial and error" stage up to date. The level of a strain-induced ionic transport enhancement is currently not converged yet due to the lack of a commonly agreed explanation on how ions hop nearby the complex defects in solid oxides under deformation. To meet this need, this proposal presents a plan to probe the coupled dynamics between the defect structure evolution and the ion diffusion in solid oxides under deformation through multiscale computer simulations. One goal of this project is to find methods of generating fast ionic transport channels through patterning the defects in plastically deformed materials. To achieve this goal, the research objective is to determine: (i) the connection between the defect-induced high local stresses, structure distortion, and the ion mobility; (ii) the decisive factors, such as dislocation configurations, grain sizes, layer thickness, lattice mismatch strain, among several, that dictate the ion transport in solid oxides with a complex microstructure; and (iii) the link between the applied loading, the strain/stress localization, and the theoretical limit of a strain-induced ionic transport enhancement. The gained knowledge may provide a preliminary guidance on how to use a well-controlled mechanical deformation to improve the material's ionic conductivity. It can support the rational development of high-performance materials with a wide range of applications in fuel cells, bio-chemical sensors, perovskite solar cells, Li-, and Na-ion batteries.