Papers by Author: Erich H. Kisi

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Authors: Oliver Kirstein, Jian F. Zhang, Erich H. Kisi, D.P. Riley
Abstract: The ternary carbide Ti3SiC2 is the archetype of MAX phases. To date, MAX phases have proven difficult to synthesize as sufficiently large single crystals from which single crystal elastic constants might be obtained. Therefore, the elastic properties not only of Ti3SiC2 but other MAX phases are extensively studied by ab initio methods. Recently single crystal elastic constants were experimentally determined for the first time using neutron diffraction. The experiment revealed extreme shear stiffness which is not only quite rare in hexagonal materials but also strongly contradicts the predictions of all published MAX phase elastic constants from ab initio calculations. In the present paper we would like to show that such shear stiffness can possibly be supported by ab initio calculations and the calculated phonon dispersion along high symmetry directions.
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Authors: Kate P. Suppel, Jenny S. Forrester, Gregg J. Suaning, Erich H. Kisi
Abstract: Single crystal sapphire in one of four orientations (0001), (11 2 0), (1102) and (1010) was bonded to polycrystalline platinum foil at 1330oC under light load 20 N (0.8 MPa) in argon. The different orientations were used as a means to model individual grains within a polycrystal without the uncertain influence of grain boundaries and glass-forming contamination (e.g. SiO2). Partial bonding was observed in all cases. Optical microscopy, scanning electron microscopy (SEM) and X-ray photoelectron spectroscopy (XPS) were used to study the nature of the bond which appears to be physical rather than chemical, in agreement with previous work.
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Authors: Ranjan Rajoo, Erich H. Kisi, D.J. O'Connor
Abstract: This paper presents data obtained from a newly-developed instrument to test the quality of solder interconnections at high strain rate – the ‘micro-impactor’. This shear test of the interconnection at high strain rate mimics the stress experienced by the solder joint when undergoing shock due to drop-impact. Instrumented with a load cell and linear variable displacement transducer (LVDT), it also has the ability to provide dynamic impact force and displacement data. Earlier concepts to characterise the solder joint at high strain rates such as the miniature pendulum impact tester [1] lacked this capability. This micro-impactor was used to study the effect of increasing silver (Ag) and copper (Cu) concentration in solder alloys on the shear strength of the solder joint. The performance of these lead-free alloys was also compared to that of the well-established leaded solder. It was found that increasing the silver content increases the yield strength of the solder, causing the failure to occur at the brittle intermetallic layer instead of in the bulk of the solder.
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Authors: Erich H. Kisi, Trevor R. Finlayson, J.R. Griffiths
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Authors: De Ming Zhu, Erich H. Kisi
Abstract: BNC nanotubes were prepared by a high-energy ball milling and annealing method. Graphite carbon (C) and hexagonal boron nitride (h-BN) powder was first milled at room temperature to generate highly disordered nanoporous particles with a metastable structure. Upon elevated temperature annealing up to 1300 °C, these nanoporous particles were chemically and thermally activated to grow BNC nanotubes with both cylindrical and bamboo-like morphology. The cylindrical tubes have smaller diameters from 40 to 60 nm and lengths up to 2 μm. The bamboo tubes have larger diameters from 80 to 150 nm and lengths up to 10 μm. The formation mechanisms of different nanostructures are discussed.
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Authors: Oliver Kirstein, Jian F. Zhang, Erich H. Kisi, D.P. Riley, M.J. Styles, Anna Maria Paradowska
Abstract: The ternary ceramic Ti3AlC2 has an interesting combination of electrical, thermal and mechanical properties. Single crystal elastic constants under the Reuss approximation for the micromechanical state were obtained by analysing the shifts of neutron diffraction peaks while a polycrystalline sample was subjected to a compressive load varying from 5 to 300 MPa. The values of Young’s modulus and Poisson’s ratio computed from the single crystal compliances are in good agreement with those obtained directly from strain gauges and from the average changes in the a and c unit cell parameters.
2417
Authors: Erich H. Kisi, Christopher M. Wensrich, Vladimir Luzin, Oliver Kirstein
Abstract: The unique and unusual state of matter represented by granular materials has historically made it very difficult to develop models of stress distributions and was previously not able to be explored experimentally in the required detail. This paper reports the application of the neutron diffraction strain scanning method, originally developed for residual stress measurements within engineering components, to the problem of the stress distribution in granular Fe under a consolidating pressure. Strains were measured in axial, radial, circumferential and an oblique direction using the neutron strain scanning diffractometer KOWARI at ANSTO (Sydney). The full stress tensor as a function of position was able to be extracted for both straight walled, converging and stepped dies.
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Authors: C. Curfs, A.E. Terry, G.B.M. Vaughan, Erich H. Kisi, M.A. Rodriguez, Å. Kvick
Abstract: Combustion synthesis techniques have been applied to an equiatomic mixture of Aluminium, Nickel, Titanium and Carbon powders in order to obtain NiAl/TiC composites. Both combustion modes have been used: the Self-propagating High-temperature mode (SHS), in which the reaction propagates through the sample under the form of a heat wave and the Thermal Explosion mode (TES), in which the reaction occurs simultaneously in the complete sample. The reactions have been followed in-situ by time-resolved diffraction, using synchrotron X-rays for the SHS mode and neutrons for the TES mode. Scanning Electron Micrographs and X-ray diffraction patterns of the final product have shown that the same final products were obtained when the mixture was synthesised under both combustion modes: a composite made of small and round TiC particles (~1 micron) embedded into a matrix of larger NiAl grains (5 microns). However, the Time-Resolved Diffraction studies have shown that, even with the same final products, the two combustion modes follow two completely different routes. Thus, for the SHS mode, the reaction is triggered by the formation of Nickel Aluminide and 3 intermediate phases are observed, and for the TES mode, the self-sustained reaction starts with the formation of Titanium Carbide and no intermediate phases have been seen.
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