Tag: Spring 2012

Materials Characterization using Scattering Techniques

Monday, February 27, 2012 3:00 pm – 4:00 pm
Room 610, M&M Building

Heinz Nakotte
Gardiner Professor, Chair of the Engineering Physics Committee, Department of Physics, New Mexico State University
and
Instrument Scientist, Single Crystal Diffractometer (SCD), Los Alamos Neutron Science Center, Los Alamos National Laboratory

Abstract

In many cases, materials properties of interest for applications are determined by the structuralfeatures at atomic, nano and/or micron level. While diffraction typically only provides a measureof the volume-averaged structure of the material of interest, the local structure is accessiblethrough total-scattering studies in combination with pair-distribution function analysis. In mylecture, I intend to discuss and compare the opportunities and limitations of total-scatteringstudies using neutrons and synchroton X-rays. I will present some recent results of two of myresearch projects, i.e. local structure of a non-platinum catalyst and evidence for resonant unitmodes in a framework structure that exhibit negative-thermal-expansion behavior. If time permits,I will also provide a brief summary of my other research projects.

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Mesoscale Anisotropic Deformation and Damage Nucleation In Polycrystalline Ti Alloy

Friday, February 24, 2012 3:00 pm – 4:00 pm
Room 610, M&M Building

M. A. Crimp
Chemical Engineering and Materials Science
Michigan State University, East Lansing, MI

Abstract

A combination of experimental characterization and crystal plasticity finite element modeling(CPFEM) has been used to study the anisotropic deformation of a number of titanium alloys.Studies have been carried out in the near surface region of 4-point bend specimens, where theglobal stress can be approximated as uniaxial tension.  Specific microstructural patches havebeen characterized prior to deformation using electron backscattered electron diffractionorientation imaging microscopy (OIM).  Specimens have been deformed both in-situ in scanningelectron microscopy (SEM) and ex-situ, facilitating a range of experimental characterizationmethods including optical microscopy, atomic force microscopy, SEM based backscatteredelectron imaging, OIM, and channeling contrast imaging, as well as 3-D X-ray diffraction.  Thesestudies have allowed a comprehensive experimental characterization of the nature of plasticdeformation and damage nucleation in the microstructural patches.  To complement thesestudies, quasi 3-D FEM meshes, developed based the experimentally characterizedmicrostructural patches, have been computationally deformed.  While the simulations accuratelyreproduce significant aspects of the experimental studies, including some crystal rotations andsurface topography development, further work to include grain boundary behavior in thesimulations is needed.

More information: Mesoscale Anisotropic Deformation and Damage Nucleation In Polycrystalline Ti Alloy

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BaTiO3 Glass-Ceramics Composites For High Energy Storage Capacitors

Thursday, February 23 2012 2:00 p.m.
Room 610, M&M Building

Douglas B. Chrisey
Department of Material Science and Engineering, Department of Biomedical Engineering
Rensselaer Polytechnic Institute, Troy, NY, 12180

Abstract

Renewable energy sources require large-scale power storage so that their inherently intermittent supply of power can meet demand.  For capacitive energy to have the necessary high volumetric and gravimetric energy storage density this will require the dielectric layer to simultaneously possess a high dielectric constant and a high breakdown strength, e.g., in excess of 10,000 and 1 MV/cm, respectively.  To be a realistic solution for renewable energy storage, it must also be low cost and scalable, i.e., no roadblocks from the laboratory prototype to large scale production, and to achieve the all of the aforementioned requirements we have exploited a glass-ceramic phase.  It is expected that glass-ceramics composites will have higher breakdown strength than that of a sintered ceramic alone, because the glass would displace the air-filled voids.  Due to the dielectric mixing rule, the dielectric constant of the composite mixture will then be limited by the low permittivity of the glass phase in comparison to the ceramic phase.  In our work, we use a glass phase that can undergo a phase transformation into BaTiO3-precipitating glass-ceramic by controlled crystallization (annealing temperature).  The benefit of doing this is that we achieve a higher dielectric constant of composite mixture, due to the additional high dielectric constant BaTiO3 phase, while also improving the high breakdown strength. It was demonstrated that this BaTiO3-precipitaing glass-ceramic and BaTiO3 ceramic composite are promising for improved dielectric properties for high-density energy storage capacitors.

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Design, Analysis, Testing, Filling and Sealing HIP Cans for the Calcine Disposition Project at the Idaho National Engineering Laboratory

Friday, February 3, 2012 11:00 am – 12:00 pm
Room 610, M&M Building

Dr. Delwin C. Mecham
CWI (Idaho National Engineering Laboratory)

Abstract

The Calcine Disposition Project (CDP) of the Idaho Cleanup Project (ICP) hasthe responsibility to retrieve, treat, and dispose of the calcine stored at theIdaho Nuclear Technology and Engineering Center (INTEC) located at theIdaho National Laboratory in Southeast Idaho.  Calcine is the product ofthermally treating, or “calcining”, liquid high-level or sodium-bearing nuclearwaste produced at INTEC from 1963 to 1998 during the reprocessing of spentnuclear fuel (SNF).  The CDP is currently completing the design of the HotIsostatic Pressure (HIP) treatment process for the calcine to produce a volumereduced, monolithic, glass-ceramic waste form suitable for transport anddisposition.Conceptual design for the CDP requires the design of a large scale HIP canwhich maintains containment of calcine during the HIP treatment cycle. The HIPcan must be filled with calcine and additives and sealed remotely. The HIP cans will undergo approximately 50%volume reduction at a temperature of 1000-1250°C and a pressure of 50-100MPa.  The HIP can’s main function isto provide primary containment of the radioactive calcine material during and after the HIP treatment process.Development of a virtual testing program using high fidelity modeling techniques is required due to the prohibitivecost of full-scale testing using actual HLW calcine.This presentation will  describe current design, analysis, and testing of HIP cans and the design for filling andsealing HIP Cans.  The basic HIP technology is summarized and the remote HIP can fill and seal design ispresented.  Simulation models are developed to establish a virtual testing program using Finite Element Analysis(FEA).   Software packages COMSOL and ABAQUS are being used to analyze the thermal and structural responseof HIP cans during the HIPing process.  The software packages increase the understanding of can deformation andallow for virtual testing before large scale testing of the HIP cans.  This decreases the number of physical HIP cantests needed during the development of a HIP can design.  The models utilize a macroscopic representation of thegranular material “constitutive model” for the material inside the can and a non-linear representation of the stainlesssteel. Initial small scale testing of HIP cans has been performed to benchmark the FEA analysis and providevalidation of the constitutive models used.  Analytic results, test data, and comparisons between them are presented.

Biography

Dr. Del Mecham has forty years of experience in the planning and management of large-scale thermal-hydraulicexperiments including the development and application of thermal-hydraulic computer codes for nuclear reactor safety analysis.Dr. Mecham has developed and managed irradiation testing programs and has participated on national and internationalresearch technical advisory boards.  Del received his PhD in Mechanical Engineering from Utah State University and is aRegistered Professional Engineer in the State of Idaho.  Dr. Mecham serves on the Industrial Advisory Committee forMechanical Engineering at Utah State and holds an Adjunct Professor position at the University of Idaho.

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