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 Computer simulated grains (top) and the arrangement of their neighbors (below). Correctly delineating the faces was critical for identifying grain topology that determines which neighbors grow and which disappear.

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: • UF graduate student David Rule traveled to the European Synchrotron Radiation Facility (ESRF) to perform 3D imaging of grains undergoing grain growth. Dr. Erik Lauridsen of Riso Laboratory in Denmark provided the training in this unique technique. The results of this study will be compared with 3D simulations of grain growth being performed by UAB co-researchers in this program, under the guidance of Dr. Veena Tikare of Sandia National Lab. Graduate student David Rule(right) gained valuable experience working with Dr. Erik Lauridsen (left) from Riso Laboratory (Denmark) at the European Synchrotron Research Facility (ESRF) performing 3D imaging of grain growth.