Leonid A Bendersky is a Research Scientist at Materials Science and Engineering Laboratory of National Institute of Standards and Technology (NIST). He received his PhD degree in Materials Science from the Technion, Israel in 1982. From 1983 he has been with NIST working on a variety of advanced materials and technologies including rapid solidification, quasicrystals, structural intermetallics, functional oxides, hydrogen storage and Li-ion batteries. His research is focused on applying advanced transmission electron microscopy and crystallography to understand structural phase transitions and relation between properties and structures. He is the author of over 200 publications.
Besides being of technological interest, thin films of different battery components, especially active cathode materials, can be utilized for fundamental studies of the processes that govern the battery’s properties. Cathodes utilized in commercial lithium batteries are complex systems consisting of a polycrystalline active material in the form of a powder mixed with conductive carbon and a binding material. A simple system with no additives is desirable for use in the investigation of interfacial reactions, especially for local microstructural studies by transmission electron microscopy (TEM). Such systems, when synthesized in the form of a thin film, especially as a single (or pseudo-single) crystal epitaxial film, can provide powerful insight into the processes occurring on a well-described two-dimensional interface, as well as the film interior. In our recent works we successfully utilized LiCoO2 epitaxial films to study details of structural changes during electrochemical cycling. In the work presented here the similar approach was extended to other important cathode systems, as well as for studying some solid electrolytes.
K Wierzbanowski has his expertise in the field of mechanical properties of metals, residual stresses and crystallographic textures. He developed crystalline models for elastoplastic deformation and for recrystallization of metallic materials. He performed also analysis and interpretations of experimental results in the domain of X-ray diffraction, electron backscattering diffraction (EBSD) and mechanical testing. He gives academic lectures in the field of General Physics and Material Science. He is author of 180 publications and of numerous presentations in conferences dedicated to material science.
Asymmetric rolling process is a subject of many research works in the last years. In this kind of rolling some technological parameters can be modified, like: normal force and torque, sample shape (by bending) and power requirements. The material properties are also noticeably modified. An important shear deformation, characteristic for this process, leads to texture rotation, microstructure refinement and increase of material strength. Asymmetric rolling can be realized by a modification of existing rolling mills, therefore its industrial application is possible at a relatively low cost. The aim of the present study was to characterize this process and resulting material modifications of face centered cubic (fcc) and hexagonal close packed (hcp) metals: aluminum, copper and titanium. The cases of low and high deformations were examined. The electron backscatter diffraction (EBSD), X-ray diffraction (XRD), calorimetry and microhardness measurements were performed. Texture and mechanical characteristics were studied using a crystal deformation model and finite element method (FEM). The following material and process modifications were found as a result of asymmetric rolling: sample bending, which can be partly controlled; decrease of mill load and an increase of the average rolling torque; increase of microhardness mechanical strength; increase of energy released during recrystallization; texture rotation around transverse direction; decrease of the average grains size (persisting in some extent also after recrystallization) and formation of more fragmented grains and; modification of lattice misorientation distributions.