Anthony D. Rollett
Department of Materials Science & Engineering
Professor Rollett’s research program emphasizes quantification of microstructure, especially in three dimensions, and its impact on properties and processing using both computational and experimental techniques. Important recent results include the effect of second phase particles on grain size stabilization in superalloys; investigation of orientation gradients development in metals; development of constitutive relations for sheet metal formability; measurement of anisotropic grain boundary energies and mobilities; development of methods for synthesizing statistically representative three dimensional microstructures; measurement and modeling of texture development during processing (recrystallization) in aluminum alloys; effect of solute on boundaries and triple junctions. The ultimate aim is to put microstructure-properties relationships on a quantitative basis for the prediction and optimization of materials processing and application. He has been responsible for a number of international conferences and is an author of over 160 scholarly articles.
ADVANCES IN 3-DIMENSIONAL CHARACTERIZATION AND MODELING OF MATERIALS
There have been substantial advances in modeling and simulation of microstructure in 3D that have significant potential for accelerating materials development where microstructure-sensitive properties such as fatigue are concerned. The progress in modeling has been accompanied by equally significant advances in characterization techniques, with serial sectioning, synthetic microstructure generation and synchrotron radiation all contributing strongly. Image-based methods for solving elastic, viscoplastic and elasto-viscoplastic problems are now available to complement finite element methods. The image-based methods sidestep the difficulty of generating meshes that conform to 3D microstructures while preserving mesh quality. The FFT-based simulations originated by Pierre Suquet and Ricardo Lebensohn provide an example. The ability to simulate problems with up to a billion points permits many aspects of heterogeneity in deformation to be investigated. Materials can also be orientation mapped non-destructively in 3D thanks to penetrating radiation at synchrotrons, which permits microstructural evolution to be characterized. High Energy X-ray Diffraction Microscopy (HEDM) is a prime example of this approach. Synthetic microstructure generation with tools such as Dream.3D now includes distributions of orientation, grain boundary character and grain morphology, even fitting the tails of distributions. Examples are given of experiment-simulation comparisons of fatigue cracking in superalloys, thermoelastic stresses in thermal barrier coatings, mechanical twinning in Zr, orientation change and gradients in copper, and thermoelastic generation of tin whiskers.