Mechanical deformation and failure processes such as ductile fracture under quasistatic loading conditions and spall at high strain rates are inherently multiscale processes, ranging from nanoscale void nucleation mechanisms to collective dislocation interactions ranging across hundreds of microns. These interactions are heavily influenced by microstructure features such as grain boundaries and second phase particles. Understanding these processes requires multiscale characterization approaches that reflect the nature of the processes and that are capable of quantifying both the local microstructure and deformation state. Advances in electron detector technology, including the advent of direct-electron detectors, and increases in computational processing capacity have transformed electron microscopy-based characterization into a big-data analytics tool capable of multimodal image acquisition and high-resolution property mapping. This includes the ability map out the three-dimensional elastic strain tensor, crystal rotations, and dislocation density at length scales ranging from nanometers to hundreds of microns.
In this talk, I will discuss the work my group is doing in applying advanced multiscale electron-microscopy based characterization techniques to understand mechanical deformation and failure mechanisms in two systems: spall failure in high strain rate deformation of additive manufactured stainless steel and understanding the influence of second phase particles in ductile failure of Al alloys. I will discuss the role of microstructure and loading conditions in inducing twin nucleation and dislocation accumulation as well as the unexpected degree of highly localized grain refinement present in both systems.