1. Fundamentals of Multicomponent Diffusion in Multiphase Alloys Yongho Sohn, University of Central Florida, DMR 0238356 Motivation: Diffusion plays an important role in development and applications of materials that underpin many products and processes. This program aims to advance in phenomenological descriptions and experimental techniques for understanding multicomponent-multiphase diffusion through an integration of fundamental laboratory research and education/outreach programs. Experimental Research: Interdiffusion Between NiAl and Various Superalloys (in Collaboration with Siemens, GE and Exxon-Mobil). Ternary Diffusion in L1 2 Ni 3 Al with Ternary Alloying Addition of Ir, Ta and Re (in Collaboration with NIMS, Japan). Study of Ternary Diffusion and Phase Equilibria in U-Mo-Al-X Alloys (X = Si, Zr, Ti, Nb) for Nuclear Fuel Applications (Synergistic Research Contract from Idaho National Laboratory). Microstructural Evolution (i.e., Multiphase Diffusion Couples) in Fe-Ni-Al and Ni-Cr-Al Alloys (in Collaboration with Oak Ridge National Laboratory Ternary Diffusion and Oxidation in Ni-Cr-X and Fe-Ni-Cr-X (X=Al, Si, Ge, Pd) Alloy (in Collaboration with ORNL). Three Phase Equilibria in Ternary Alloys Uphill Diffusion of Al by Ta Addition Facility Development Experimental Facility Dedicated for Diffusion Studies: Arc Melt, Quartz Capsule, Hydrogen Flush System, Furnaces and Electron Probe Microanalysis. Microstructure Modeling Phase-Field Simulation of Multiphase Ternary Diffusion Couple with Composition- Dependent Thermodynamics and Mobilities. Developed Framework for Generalized Description of Interdiffusion Fluxes under Multiple Gradients. Microstructural Analysis and Quantitative Assessment of Interdiffusion Between NiAl and Various Superalloys Three phase equilibrium,   ’ (BCC) and  (FCC), in a ternary diffusion couple in Fe-Ni-Al alloy. Alloying Addition of Si in Al-Cladding Alloy Reduced the Thickness of Intermetallic Layer by an Order of Magnitude for U-Mo Nuclear Fuels. Composition Dependent Microstructural Development via Phase- Field Simulation

2. Fundamentals of Multicomponent Diffusion in Multiphase Alloys Yongho Sohn, University of Central Florida, DMR 0238356 Education and Traineeship Mr. N. Garimella who is Working on Interdiffusion in Ni- Cr-X and Fe-Ni-Cr-X (X = Al, Si, Ge, Pd) with NSF Support is Expected to Defent in Dec., 2007. Mr. R. Mohanty who is Working on Multiphase Interdiffusion with NSF Support is Now a Doctoral Candidate. Ms. A. Ewh (Honors Freshman; Previous Participant of Outreach Program) Has Joined Our Diffusion Team and Made Spectacular Progress in Research. Mr. E. Perez who Earned M.S. with NSF Support is now a Ph.D. Student working on a Project from Idaho National Laboratory, Interdiffusion in U-Mo-Al Alloys. Mr. T. Patterson (B.S.) who Assisted This NSF Program Has Entered Ph.D. Program in Materials at UCF. Mr. Nathan Hotaling (B.S.) Graduated with B.S. and Has Entered PH.D. Program in Materials at Georgia Tech. Ms. A. Leon (Senior) Continue to Contribute to This Program as Undergraduate Research Assistants. Broader Impact / Outreach  Hosted a Number of Activities to Increase the Awareness of Materials Science and Engineering to K-12 Students and Teachers, with Emphasis on Girls.  PI was invited by National Institute for Materials Science of Japan as Guest Scientist and Established Collaboration (1 Published; 1 Submitted Paper).  PI Organized 6 International Symposiums (MS&T, TMS and ACERS), Gave Plenary Lecture at DSL07 and Invited Talk at MS&T. Schedule for Invited Talk at MRS 2007 Fall Meeting.  Guest Edited JPED (Vol. 27, 2006) and DDF (Vol. 266, 2006) on Diffusion Focus Issues. Sohn Group, Spring 2006 World’s Diffusion Experts at The Banquet After Symp. in Honor of Prof. Dayananda Organized by PI