Topological Grain Growth Burton R. Patterson, University of Florida, DMR 1035188

1. Topological Grain GrowthBurton R. Patterson, University of Florida, DMR 1035188 • Metals are comprised of crystals, called “grains”, whose size controls their strength and other properties. Annealing, or heating in a furnace, results in their “faces” or surfaces moving in a direction proportional to their size, number of faces or “Topology” , and curvature. • Theoretically- • Largest grains (concave, many faces) grow • Smallest grains (convex, few faces) shrink, disappear • Average “grain size” increases , metal softens • Process very important to industry, butnot well understood, • grains are opaque • growing and disappearing grains can’t be watched! • Novel 3D computer simulation and X-ray methods now allow these growing, shrinking and disappearing grains to be studied in real time. Early results indicate that the growth and shrinkage rates of grains are actually proportional to the number of their faces, or “topology”. …fulfilling a theory developed long before these new visualization methods were developed. Theory proved! time 1 time 2 3D computer simulation of grains growing (most grains), shrinking and disappearing (yellow), depending on their “topology” or number of faces

2. Topological Grain GrowthBurton R. Patterson, University of Florida, DMR 1035188 • Several valuable interactions, training experiences and international collaborations have taken place through this program, including: • UAB graduate student Zhiwei Sun was hired to work at Sandia National Laboratory , Albuquerque, through the summer of 2010, gaining valuable experience in 3D simulations of grain growth. • UF graduate student Kristofer Hannesson is collaborating with Riso National Lab (Denmark) performing complex analysis of 3DXRD • data for imaging grains in three dimensions . Graduate student Zhiwei Sun gained valuable experience working with Dr. Veena Tikare at Sandia National Laboratory, Albuquerque, throughout the summer of 2010.