Journal: International Journal of Materials Research

Abbreviation

Int. J. Mat. Res.

Publisher

Hanser

Journal Volumes

ISSN

1862-5282
2195-8556

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Publications 1 - 10 of 19
  • Ni-Based SOFC Anodes: Microstructure and Electrochemistry
    Item type: Journal Article
    Bieberle, Anja; Gauckler, Ludwig J. (2001)
    International Journal of Materials Research
    The electrochemical behavior of Ni-based SOFC anodes with different microstructures was studied. The anodes consisted either of a Ni gauze, a Ni pattern, a Ni paste, or a Ni -YSZ cermet. According to electrochemical impedance spectroscopy (EIS) measurements, the anodes are dominated by two main processes. The high frequency process decreases exponentially with an applied overpotential and is thermally activated with an activation energy of around 1 eV. The process could be attributed to the adsorption of hydrogen including charge transfer. The low frequency impedance arc arises only under a high overpotential applied between the working and the reference anode. The impedance of this process increases the higher the overpotential and is thermally activated with an activation energy of 0.5 eV. This process is assigned to the desorption of water.
  • Nanograin size, high-nitrogen austenific stainless steels
    Item type: Journal Article
    Speidel, Markus O. (2003)
    International Journal of Materials Research
  • Design strategy for new biodegradable Mg–Y–Zn alloys for medical applications
    Item type: Journal Article
    Hänzi, Anja C.; Sologubenko, Alla; Uggowitzer, Peter (2009)
    International Journal of Materials Research
  • Site preference, thermodynamic, and magnetic properties of the ternary Laves phase Ti(Fe₁ – ₓAlₓ)₂ with the crystal structure of the MgZn₂-type
    Item type: Journal Article
    Yan, Xinlin; Chen, Xing-Qui; Grytsiv, Andriy; et al. (2006)
    International Journal of Materials Research
    Site preference and thermodynamic properties of the ternary Laves phase Ti(Fe1 -xAlx)(2) with MgZn2-type have been studied employing Rietveld refinement of X-ray and neutron powder diffraction data, X-ray single crystal data, and isoperibolic drop calorimetry techniques. A detailed relation between lattice parameters of Ti(Fe1- xAlx)(2) and the Al content in the Laves phase has been presented. The Rietvelt refinement revealed that Ti atoms occupy the 4f site in the MgZn2-type, whilst Fe and Al atoms randomly share the 2a and 6 theta site. Heat of formation has been measured for Ti(Fe0.5Al0.5)(2). For the ab initio density functional theory applications, a large number of structural models were investigated to calculate the concentration dependent (Al) heats of formation, magnetic structural stabilities, lattice parameters, and site occupancies, which are in good agreement with experiment.
  • Isothermal Sections of Phase Equilibria in the Al-AlCo-AlNi System
    Item type: Journal Article
    Gödecke, Tilo; Scheffer, Max; Lück, Reinhard; et al. (1998)
    International Journal of Materials Research
    The phase equilibria of the ternary Al-AlCo-lNi system are demonstrated using isothermal sections at 1170, 1100, 1050, 900, 850, 730, and 600 degrees C. These are based on metallographic and TEM investigations and on several temperature-concentration sections, which are investigated using thermal analyses. The Scheil reaction scheme is used for explanation of the data. Eleven phases from the binaries Al-Co and Al-Ni and the three ternary phases Y-2 (Co2NiAl9), X and D were found at room temperature. The binary high-temperature phase Co4Al13(h) is stabilized in the ternary down to room temperature by Ni addition (Y-1). The phase field of D is composed of several modifications which can hardly be distinguished by light microscopy. These modifications are not considered in the present paper. 45 three-phase regions can be derived from the reaction scheme in the Al-AlCo-AlNi subsystem.
  • Thermodynamic assessment of the Mn-Cr-O system for solid oxide fuel cell (SOFC) materials
    Item type: Journal Article
    Povoden, E.; Nicholas Grundy, A.; Gauckler, Ludwig J. (2006)
    International Journal of Materials Research
  • Processing of dense MgO substrates for high-temperature superconductors
    Item type: Journal Article
    Köbel, Stefan; Schneider, D.; Gauckler, Ludwig J. (2003)
    International Journal of Materials Research
    Sintering of magnesium oxide ceramics to high density requires high temperatures (1500-1800 degrees C), resulting in coarse-grained microstructures, or additives that promote sintering. An alternative is to use a fine-grained MgO starting powder with an impurity level < 1 % that allows appropriate processing conditions. Here, we report about processing by slip casting, resulting in ceramic green bodies that can be sintered to closed porosity at 1600 degrees C. X-ray diffraction and scanning electron microscopy combined with energy-dispersive X-ray spectroscopy showed that the sintered bodies are single-phase. The process described here is suitable to sinter large substrates up to 200 mm x 200 mm and 96 % of the theoretical density with closed porosity. The MgO substrates are suitable for partial melt processing of high-quality Bi-2212 thick films.
  • Recent progress in the area of bulk metallic glasses
    Item type: Journal Article
    Löffler, Jörg F. (2006)
    International Journal of Materials Research
    Bulk metallic glasses (BMGs) form a new class of alloys which can be manufactured amorphously at a cooling rate of less than 100 K/s and in dimensions of several centimeters. Because of their particular characteristics, these glassy materials have great potential for deployment as structural and functional materials. The mechanical, magnetic, and thermophysical properties of this new materials group and the advantages they promise for the processing and manufacturing of components are presented. The possibilities for deploying bulk metallic glasses in medical devices and lightweight construction are also set out. In these two areas, we discuss some results as to the biocompatibility of metallic glasses and their potential use in vascular intervention, as well as the properties of light-metal-based bulk metallic glasses in connection with their potential as a construction material. We also present ideas concerning the development of corrosion-resistant Mg-based glasses, and the manufacture and processing of light-metal-based composites.
  • Aluminum-lithium alloy development for thixoforming
    Item type: Journal Article
    Sauermann, Roger; Friedrich, Bernd; Püttgen, Wolfgang; et al. (2004)
    International Journal of Materials Research
    This paper presents a scientific contribution to the development of lightweight/high-performance Al -Li alloys suitable for semi-solid processing. Thermodynamic calculations identified the most promising compositions with focus on the solidus - liquidus interval, fraction of solid-versus-temperature and phase reactions. The synthesis of Al -Li precursor billets was performed by overpressure induction melting in controlled atmosphere. DTA and microstructure investigations on Al -Li specimens were carried out as well as thixocasting trials of demonstrator components. New rheocasting of Al -Li alloys was investigated to identify the potential of this alternative precursor material route. It is shown that specifically developed Al -Li alloys offer great potential for semi-solid manufacturing.
  • Magnetoplasticity
    Item type: Journal Article
    Kostorz, Gernot; Müllner, Peter (2005)
    International Journal of Materials Research
    Magnetocrystalline anisotropy and twinned microstructure are at the origin of the appreciable magnetic-field-induced strains found in some ferromagnetic thermoelastic martensites. The change of magnetization across the twinning plane leads to a force on the twinning dislocations when a magnetic field is applied. The sensitivity of this basic microscopic mechanism not only to crystallographic and magnetic properties of the material, but also to microstructural details, leads to a large variance in the macroscopically attainable magnetic-field-induced strains, while the maximum strain is fixed for any given martensite structure. The magnetic-field-induced deformation of Ni–Mn–Ga single crystals was studied in uniaxial (“static”) and rotating (“dynamic”) magnetic fields. The spatial and orientational distribution of martensite domains, twin thickness and mutual interactions between twinning dislocations all contribute to the macroscopic result.
Publications 1 - 10 of 19