SaM Seminar Series: Tony Rollett

Professor of Materials Science & Engineering, Carnegie Mellon University

Member of the NSF-Supported Materials Research Science and Engineering Center

Focal Area Point of Contact for Computational Chemistry and Materials, Department of Defense High Performance Computing Program

Fellow of the Institute of Physics (United Kingdom)

Fellow of ASM-International

Computer Simulation of Materials Properties & Processing

Friday, February 13, 2:30 – 3:30 PM
1175 Benedum Hall

The reason that solids materials are so fascinating is that, unless they amorphous (glassy), they possess microstructure and this microstructure, or ensemble of defects, largely dictates their properties, performance and lifetime. Furthermore, materials are not “born” in final form but must be processed, whether via solidification, powder processing, vapor deposition or thermomechanical processing, to name but a few of the possibilities. In addition to using computer simulation as a scientific tool, there is also the ultimate goal of employing simulation techniques to speed up materials development cycles by analogy to the design of aircraft, for example. In contrast to only having to solve the fluid flow equations, however, materials modeling must include many different phenomena and over a wide range of length scales.

This talk will focus on the mesoscale, meaning length scales (and time scales) that bridge between the atomistic and continuum. Examples will be given of how computer simulation has illuminated our understanding of grain growth, recrystallization, fatigue crack growth, and the heterogeneity of plastic deformation both in single-phase polycrystals and in composite materials. For example maintaining a fine grain (crystallite) size is critical to many structural materials. This is generally accomplished with fine dispersions of second phase particles but the phenomenon of abnormal grain growth occasionally defeats this control measure. Recent results will be reviewed that illuminate this poorly understood process. Similarly, many processes in materials, such as recrystallization and fatigue crack nucleation, depend on the upper tails of distributions of stress or strain. Quantitative analysis of such limits using simulations of polycrystal plasticity leads to interesting insights.