Interfaces, Grain Boundaries and Surfaces from Atomistic and Macroscopic Approaches -- Fundamental and Engineering Issues: Interface Dynamics
Sponsored by: MS&T Organization
Program Organizers: Wayne Kaplan, Technion - Israel Institute of Technology; Paul Wynblatt, Carnegie Mellon University; Dominique Chatain, CNRS, Aix-Marseille University; Mikel Holcomb, West Virginia University
Tuesday 8:00 AM
October 18, 2011
Room: C120
Location: Greater Columbus Convention Center
Session Chair: Mark Asta, University of California, Berkeley ; Gerhard Dehm, University of Leoben
8:00 AM Keynote
Key Stages in Reactive Spreading: Eduardo Saiz1; Antoni Tomsia2; 1Imperial College; 2Lawrence Berkeley National Laboratory
The reactive spreading of high-temperature liquids is behind multiple technological applications from brazing, to soldering or the fabrication of composites. However, the physicochemical phenomena that control spreading in reactive systems is still the matter of discussion. The objective of this presentation is to review recent advances in the experimental and theoretical analysis of the high-temperature spreading of molten metals and oxides. Results from different authors will be compared and the observed trends will be confronted. A framework for the analysis of reactive spreading is proposed. This framework is based on the division of the reactive spreading process into its constituent steps and the identification of the step that drives spreading and controls kinetics. A key aspect of the analysis is the description of the structure of the triple junction and the identification of the relative kinetics of the movement of the liquid and the other phenomena that accompany spreading.
8:40 AM Invited
The Ubiquitous Interfacial Free Energy in Phase Transformations: David Seidman1; 1Northwestern University
The interfacial free-energy of a heterophase interface is a ubiquitous and fundamental quantity in all microstructures because its short and long-term stability or lack thereof is intimately related to it. Interfacial free energy affects important physical phenomena such as nucleation, growth and coarsening of a second phase in multicomponent alloys, which are integral to the phase separation of a single-phase solid-solution. I focus on the diverse roles played by interfacial free energy in phase transformations in multicomponent metallic alloys, which are studied experimentally by atom-probe tomography and transmission electron microscopy. First-principles calculations of interfacial energies in the same metallic alloys will be discussed in terms of their relevance to all of the above. The Ni-Al-Cr, Al-Sc, and Al-Sc-Mg systems are emphasized and contrasted.
9:00 AM Invited
In-Situ TEM Investigation of Interfacial Processes in Aqueous and Environmental Systems: Shen Dillon1; 1University of Illinois at Urbana-Champaign
The transmission electron microscope is an ideal platform for in-situ investigations of nanoscale processes, due to its high spatial and temporal resolution. The technique will find broad application if it is made user-friendly and the effects of electron beam interactions can be understood and mitigated. This talk highlights our recent work characterizing solid-liquid and solid-gas interfacial reactions in-situ in the TEM. The presentation discusses electron beam induced effects and approaches to applying the technique appropriately. Recent results from in-situ electrochemisty and photochemistry experiments will be presented.
9:20 AM Invited
Silver Layer Instability in a SnO2/Silver/SnO2 Trilayer on Silicon: Carol Handwerker1; Suk Jun Kim1; Eric Stach1; 1Purdue University
Trilayers of SnO2/Ag/SnO2 on Si formed at room temperature become unstable after annealing at 100°C and 200 °C, exhibiting five phenomena – formation of internal Ag hillocks, cracking of the top SnO2 layer above internal Ag hillocks, penetration of Ag-Ag grain boundaries by SnO2 leading to grain pinch-off, formation of Ag rods and islands on the free surface of the SnO2 through the cracked top layer, and void formation in the Ag layer. The possible driving forces for the observed phenomena resulting from thermal expansion mismatch stresses and the reduction in interfacial energy will be discussed.
9:40 AM Break
10:00 AM Invited
The Effect of NiO on Microstructure and Densification in Several Oxides: Ivar Reimanis1; Joshua White1; Amy Morrissey1; Jianhua Tong1; James O'Brien2; 1Colorado School of Mines; 2Quantum Design
The presence of NiO influences the microstructure development and sintering kinetics of Y2O3-stabilized ZrO2 (YSZ), barium zironate (BZYO), and barium cerate (BCYO). The present research addresses the reasons. High sensitivity SQUID magnetometry is a useful tool because the magnetic signature allows differentiation between Ni2+ ions in solution, NiO, and Ni metal. The use of magnetometry in studying the role of NiO is demonstrated with systematic experiments in which composition and processing environment are altered. It is shown that the NiO solubility in cubic zirconia increases when the grain boundary area increases.
10:20 AM
Effect of Layer Thickness on the Heterophase Interface Character Distribution (HICD) of Accumulative Roll-Bonded Cu-Nb Composites: Jonathan LeDonne1; Sukbin Lee1; Samuel Lim2; Xuan Liu1; Amith Darbal1; Noel Nuhfer1; Nathan Mara3; Irene Beyerlein3; Katy Barmak1; Anthony Rollett1; 1Carnegie Mellon University; 2Singapore Institute of Manufacturing Technology; 3Los Alamos National Laboratory
Much investigation of layered composite materials, such as Cu-Nb, has been performed recently due to their exceptional strength with decreasing layer thickness into the nano-scale regime. In order to investigate the length scale effect on the near heterophase interface texture and the heterophase interface character distributions, multiscale composites with alternating Cu and Nb layers were produced using the accumulative roll bonding technique. The range of the average layer thickness is from 50 μm down to 20 nm. For obtaining local orientation information and geometry of such multiscale composites, both high-resolution EBSD techniques in the SEM and ASTAR techniques in the TEM were used. The HICD was evaluated for these samples as a function of layer thickness. This work is supported as part of the Center for Materials at Irradiation and Mechanical Extremes, an Energy Frontier Research Center funded by the U.S. Department of Energy, Office of Basic Energy Sciences.
10:40 AM
Abnormal Grain Growth and Grain Boundaries in Strontium and Barium Titanate: Michael Baeurer1; Michael Hoffmann1; 1Karlsruhe Institute of Technology
Perovskite type ceramics are widely used in electronic applications such as capacitors, positive temperature coefficient resistors and piezoelectric actuators. For all these applications grains size effects influence the performance of devices. Abnormal grain growth is commonly observed in all perovskite ceramics. For SrTiO3 and BaTiO3 ceramics it is known that titania rich material shows abnormal grain growth whereas Ti-deficient material shows no such behaviour but an overall enhanced normal growth. Grain boundaries in BaTiO3 showing abnormal grain growth are especially well examined and described in the literature available. All these studies explore grain boundaries after abnormal grain growth occurred and hypothesise about the nucleation mechanism of abnormal growth. In this study the nucleation rate of abnormal grains with time and temperature is used to learn about the nucleation mechanism and the results are compared to results from examinations of grain boundaries by TEM in SrTiO3 and BaTiO3.
11:00 AM
An Interface Field Model for Motion of Anisotropic Grain Boundaries: Debashis Kar1; Seth Wilson1; Jason Gruber1; Gregory Rohrer1; Anthony Rollett1; 1CARNEGIE MELLON U
An interface field method is presented in two and three dimensions to study the effect of anisotropy in interfacial energy on populations during grain growth. The steady-state morphology of isolated shrinking grains is different for varying anisotropic conditions. The effect of equilibrium at interfacial junctions on the development of interface character distribution is discussed. The interface distribution for isolated shrinking grains scales with energy, in contrast to polycrystalline systems, where an inverse relation between interface energy and population is observed. A five-parameter energy distribution for fcc metals (as nickel) is constructed using data extracted from recent molecular-static simulations by Olmsted et al [Acta Materialia 2009; 57:3694]. The interface character distribution from the phase-field simulations is compared to distributions previously extracted from orientation imaging [Acta Materialia 2009; 57:4304]. Acknowledgement: This work was supported by the Pennsylvania DCED and by the MRSEC program of the National Science Foundation under Award Number DMR-0520425.
11:20 AM
Anisotropic Hole Growth during Solid-State Dewetting of Single Crystal Fe-Au Thin Films: Dor Amram1; Leonid Klinger1; Eugen Rabkin1; 1Technion
Thin Fe-Au bilayers (12nm total thickness) were deposited by electron-beam deposition on sapphire substrates. The as-deposited bilayers were single crystalline ( <111> normal to the substrate). Atomic force microscopy and high-resolution transmission electron microscopy were employed to study the agglomeration process of the film after annealings at elevated temperatures. Experimental conditions lead to the formation of a single (Au) phase. The agglomeration begins with the formation of faceted hexagon-shaped pinholes which grow upon annealing, while changing their shape from perfect hexagons towards triangles. This suggests anisotropy of the facet's velocities, related to differences in diffusivity along the facets. The single crystalline films exhibited much-improved stability compared to polycrystalline Fe-Au and Au films of comparable thickness. A model was developed, demonstrating that surface-energy and diffusivity anisotropies govern this process. The effective self-diffusion coefficients along the facets were determined by comparing calculated and experimentally-measured hole sizes at different anneal times.
11:40 AM
Solid State Oxidation of Aluminum at the Aluminum-Sapphire Interface: Oxygen Transport Mechanism: Sreya Dutta1; Helen Chan1; Richard Vinci1; 1Lehigh University
Solid state annealing of aluminum films on sapphire substrates resulted in the development of interesting microstructural features. For example, drum-like cavities, covered with a thin membrane of γ-alumina were formed in the vicinity of annealing hillocks. Removal of the overlying aluminum using a KOH etch revealed sub-surface, hollow oxide structures at the aluminum-sapphire interface (located underneath annealing hillocks). The annealing treatment under different gas atmosphere showed that dewetting of the Al film occurred only if oxygen was present in the furnace atmosphere. The amount of oxygen required for the formation of the interfacial features was estimated based on the feature density, the size and geometry of the features, and the type of alumina phase present. Calculations showed that (apparent) values of steady state diffusion coefficients were many orders of magnitude too high to be physically reasonable. Instead, the oxidation kinetics were found to be more consistent with short-circuit diffusion.