Search

The advent of techniques enabling three-dimensional (3D) analysis of objects, defects, and fields has been key to discoveries and paradigm shifts in molecular biology, astrophysics, medicine, quantum physics, etc. In materials science, the 3D nature of materials microstructures remains largely hidden; leading to a fragmented understanding of microstructure-property linkages. Current tools cannot characterize large volumes of 3D microstructures at fine resolution. To this end, this study introduces a graph-theory-based framework to automatically extract 3D microstructures and statistics of electron-backscatter diffraction datasets. Further, leveraging network science, the study introduces a new approach to classify and compare microstructures; the keystone to materials taxonomy. The significance of this tool is demonstrated by studying deformation twin structures in Titanium. The study reveals extraordinarily complex and tortuous twin networks never observed via traditional two-dimensional analysis. This changes our perception of the ability of metals to withstand severe microstructure changes without failing.

Nickel-based alloys are extensively used in a wide range of extreme environments because of their exceptional mechanical properties. The excellent strength of these alloys is derived from the addition of long-range ordered precipitates, introduced by thermal aging. The interactions between the dislocations and LRO precipitates dictate the deformation modes and plastic response in these alloys. While the majority of studies have focused on L12-structured precipitate-strengthened Ni-based alloys, less work has considered the Ni-based alloys containing Pt2Mo-structured, Ni2(Cr,Mo)-typed precipitates. In these alloys, Pt2Mo-structured precipitates enable room-temperature deformation twinning in addition to slip, which increases strain hardenability measured from bulk mechanical testing. Although previous geometric-based model suggested that deformation twinning is favored over slip, the factors that influence the activation between twinning versus slip have not been thoroughly explored in this class of Ni-based alloys. In this work, molecular dynamics examined the possible types of dislocation and Pt2Mo-structured precipitate interactions at low temperature. Combined with in situ micromechanical testing, the role of resolved shear stresses on dislocation partials were shown to directly influence the activation of slip versus twinning. Additionally, using an energy-based approach, molecular dynamics results demonstrated a novel twin formation process, caused by the dislocation interaction with the Pt2Mo-structured precipitates.