Materials Engineering Research and Design
- Clyde Briant
- Professor Briant's research interests center on mechanical properties of materials and how these properties can be explained by various microstructural elements. Grain boundaries constitute one of the most important features of a microstructure, and one research program examines the structure of grain boundaries at the atomic level, using this structural information to interpret grain boundary fracture, deformation, and sliding. Another important area of his research is microstructure evolution during deformation. This work examines both single crystals and polycrystals and considers the formation of the initial dislocation structure and the organization of this structure into cells or tangles. This research also considers the texture that can develop in a material after extensive deformation or after recrystallization of a worked material. Another important factor in the study of the deformation is the strain rate. Equipment is available in Professor Briant's laboratory to test samples at strain rates between 10-4 to 104 sec-1. Finally, Professor Briant has a keen interest in the environmental cracking of metals. Programs are underway to examine hydrogen embrittlement of titanium and stress corrosion cracking of aluminum alloys. The focus of this work is to change the composition and heat treatment of these materials to improve their resistance to environmental cracking.
- Eric Chason
- Professor Chason's research focuses on the evolution of surfaces and thin films during materials processing. A major component of this research has been the development of real-time diagnostics that allow materials to be monitor during processing. A laser-based technique, for instance, enables stress in thin films to be measured while the films are being deposited. Stress can cause failure in thin films by cracking or de-adhesion, and being able to measure the stress while the films are growing makes it possible to explore new ways to minimize it. Other techniques have been developed to measure surface roughness, buried interfaces, film thickness and surface clustering utilizing laser beams, X-ray's, electron beams or other light sources. These techniques have been applied to understand fundamental problems of surface morphology evolution and stress relaxation in thin film structures. Current areas of research include spontaneous pattern formation during low energy ion bombardment, quantum dot formation in strained layers and Monte Carlo computer simulations of growth processes.
- K. Sharvan Kumar
- Professor Kumar's research interests include structure-property relationships in structural metals and alloys, intermetallics, metal-matrix composites, physical metallurgy, phase transformations in metallic materials, and deformation behavior. Current research activities focus primarily on intermetallic materials, refractory alloys and nanostructured materials. Examples of current research activities include understanding i) the effect of microstructure on the mechanical properties of multiphase Mo alloys, ii) in collaboration with faculty at MIT, the deformation behavior of nanocrystalline metals using electron microscopy techniques, and iii) in collaboration with scientists at Oak Ridge National Laboratory, the dislocation core structures in Laves phases and the mechanism by which deformation and phase transformations occur in materials with such complex crystal structures.
- David C. Paine
- Professor Paine's research interests are in thin film characterization and processing with a focus on interfaces and interface stability in electronic thin film systems. The evolution of microstructure as a function of processing conditions is being studied in a wide range of materials synthesized by techniques such as physical vapor deposition (MBE, dc/rf magnetron sputtering) and low pressure chemical vapor deposition. Key characterization techniques include x-ray diffraction, electron microscopy, in situ optical reflectivity and in situ resistivity. Examples of recent project topics include novel semiconductor substrate schemes, low temperature deposition of indium tin oxide transparent conductors, high pressure synthesis, and solid phase epitaxy of strained Si1-xGex.
- G. Tayhas R. Palmore
- Prof. Palmore's research interests center on linking functional biological molecules to the surface of a self-assembling electronic device. The successful integration of biological systems with electronic devices has the potential to improve the efficiency of our use of energy resources by converting chemical waste directly into electrical power through biofuel cells, to facilitate the detection of poisonous gases or hidden explosives rapidly and inexpensively through biosensors, to improve biomedical implants, and to overcome the present limitation in silicon-based computing due to current fabrication technologies through computer chips that self-assemble. Integrating biological molecules with electronics requires a scientific approach that combines chemistry with elements of biology, physics, and engineering. Accordingly, we are addressing the problem of integrating biology with electronics from two directions simultaneously: (a) by designing, fabricating and analyzing operational bioelectronic devices; and (b) by establishing a method for controlling how materials self-assemble, thus making it possible to engineer materials with specific physical properties and surface functionality.
- Janet Rankin
- Professor Rankin's research interests lie in the energetics of interfaces in fine-scale nano- and microstructures, and the control and optimization of those energetics. Specifically, her group is currently investigating the sintering of nanoscale single crystals and stress evolution in chemical vapor deposited diamond thin-films. Professor Rankin utilizes in situ electron microscopy to investigate initial-stage sintering and particle coalescence in faceted ceramic oxide powders. These studies have revealed new and exciting details of the atomistics and dynamics of neck growth and have spurred several theoretical investigations of particle coalescence in faceted systems. Additionally, Professor Rankin is interested in intrinsic stress and grain alignment in diamond films. This study utilizes high-resolution TEM and electron energy loss spectroscopy (EELS) techniques to investigate the form and the role of intergranular carbon phases on the observed stress reduction in diamond films grown with a multi-step processing scheme.
- Brian W. Sheldon
- Prof. Sheldon's research addresses processing-related phenomena in advanced materials. A major focus is the synthesis of ceramic thin films and coatings by chemical vapor deposition. These materials are of interest for a variety of structural and electronic applications. In particular, this work emphasizes understanding and controlling residual stresses. Other interests include high temperature oxidation in ceramics, and fundamental work on microstructure evolution in porous materials. Prof. Sheldon has a number collaborations with other faculty in the Divisions of Engineering, Applied Mathematics, and Biology and Medicine. Outside collaborations include work with researchers at Oak Ridge National Laboratory, and with several industrial partners.
