Nonequilibrium and metastable structures

点击翻译按钮获取中文摘要

My interests are in understanding and predicting the properties of nonequilibrium and metastable structures. These include glasses, phase separating alloys and fluids, epitaxially-grown films, solidifying crystals, polymeric plastics, and, indeed, biological systems at the microscopic and macroscopic scales.As a specific example, the structural and mechanical properties of materials, e.g, how brittle they are, and how they self-assemble, are determined by a nonequilibrium processing history. This gives rise to a complex structure on the scale of nanometers to microns. Applications make use of this complex structure by dynamically tuning the morphology to, for example, minimize failure rates of materials under stress. Alloys are strengthened by trapping lattice defects at phase boundaries through nonequilibrium processing, e.g., by subjecting the alloy to heat treatments (some prescription for raising and lowering the temperature), and cold working. What is left is not an equilibrium phase, it is a nonequilibrium material with a tuned microstructure. Often these complex structures involve scale invariance in an intrinsic and deep way, where a dominant length scale asymptotically controls the evolution of the structure on all scales. Hence, a fundamental issue in physics is involved: where do such complex structures come from, and how can they be understood?With my group, I am investigating these and other systems by nonlinear analysis, and large-scale computer simulation. We make use of ideas and analogies developed in other contexts, particularly those developed in the theory of critical phenomena -- namely the deep understanding of fluctuations, correlations, scale invariance, interface dynamics, and the focus on universal issues as manifested through modeling and large-scale simulation -- to understand the origin of complex structures.