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Liquid Region (liquid + region)
Selected AbstractsNew Metallic Glass/Alloy (MeGA) Rods Produced by Co-extrusion,ADVANCED ENGINEERING MATERIALS, Issue 10 2006S. Gravier New Metallic Glass/Alloy (MEGA)-rods with a core in bulk metallic glass (zirconium or magnesium based BMG) and a sleeve in conventional light alloys (Al-5056 and Mg-AZ31) have been elaborated by co-extrusion carried out at temperatures corresponding to the supercooled liquid region of the glass. For most glass/alloy combinations, this process leads to defect-free interfaces and therefore to good compressive strengths which can be described by the rule of mixtures. [source] Solidification of binary aqueous solution cooled from aboveHEAT TRANSFER - ASIAN RESEARCH (FORMERLY HEAT TRANSFER-JAPANESE RESEARCH), Issue 1 2010Shigeo Kimura Abstract Freezing and melting phenomena are important in many different fields, including crystal growth, casting, metallurgy, geophysics, and oceanography. Solidification of a multi-component solution is the one often observed in nature. In order to investigate basic features of the freezing processes of binary systems, we conducted a series of laboratory experiments in a rectangular box cooled from above using aqueous NaNO3 solution. During the freezing, the solid phase always grows into many needle-like crystals called the mushy layer. We measured the growth of the mushy layer thickness, the solid fraction, the temperature, and the concentration distributions. The average solid fraction is found to increase with time in the mushy layer. This causes a slow descent of the released solute in the mushy layer and its eventual fall into the liquid region below because of gravity. We propose a one-dimensional model to explain the horizontally-averaged mushy layer growth. In the model, the estimate of a heat flux at the mushy-liquid interface due to natural convection is found essential for a correct prediction. The proposed theory predicts well the growth of the mushy-layer and the average solid fraction, once the convective heat flux is properly given. © 2009 Wiley Periodicals, Inc. Heat Trans Asian Res; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/htj.20278 [source] Dendritic solidification of binary alloys with free and forced convectionINTERNATIONAL JOURNAL FOR NUMERICAL METHODS IN FLUIDS, Issue 3 2005P. Zhao Abstract Dendritic solidification with forced convection and free convection driven by contraction and thermo- solutal buoyancy is simulated in two-dimensional space using a sharp-interface model. Both pure substances and alloys are considered. The model is formulated using the finite element method and works directly with primitive variables. The coupled energy- and solutal concentration-equations, along with the Navier,Stokes equations for incompressible flow, are solved using different meshes. Temperature is solved in a fixed mesh that covers the whole domain (solid + liquid) where the solid,liquid interface is explicitly tracked using marker points. The concentration and momentum equations are solved in the liquid region using an adaptive mesh of triangular elements that conforms to the interface. The velocity boundary conditions are applied directly on the interface. The model is validated using a series of problems that have analytical, experimental and numerical results. Four simulations are presented: (1) crystal growth of succinonitrile with thermal convection under two small undercoolings; (2) dendritic growth into an undercooled pure melt with a uniform forced flow; (3) equiaxial dendritic growth of a pure substance and an alloy with contraction-induced convection; and (4) directional solidification of Pb,0.2 wt% Sb alloy with convection driven by the combined action of contraction, thermal and solutal buoyancy. Some of the simulation results are compared to those reported using other methods including the phase-field method; others are new. In each case, the effects of convection on dendritic solidification are analysed. Copyright © 2005 John Wiley & Sons, Ltd. [source] The recovery of the shear viscosity of thermally aged bulk and ribbon glassy Pd40Cu30Ni10P20 by rapid quenching from the supercooled liquid statePHYSICA STATUS SOLIDI - RAPID RESEARCH LETTERS, Issue 2-3 2009V. A. Khonik Abstract Isochronal (= linear heating) measurements of the shear viscosity below the glass transition of bulk and ribbon glassy Pd40Cu30Ni10P20 samples differing ,104 -fold in the production quenching rates have been performed. It has been found that heating up into the supercooled liquid region followed by slow cooling leads to a significant structural relaxation-induced viscosity increase upon subsequent testing. This increase, however, is not truly irreversible and the viscosity can be fully recovered (= decreased) by fast quenching from the supercooled liquid state. The effect is nearly independent of whether ribbon or bulk samples are used despite the fact that those latter are notably denser. (© 2009 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim) [source] Crystallization study of amorphous Pd43Ni10Cu27P20 alloy by internal friction measurementPHYSICA STATUS SOLIDI (A) APPLICATIONS AND MATERIALS SCIENCE, Issue 10 2007K. W. Yang Abstract We have successfully measured the internal friction and electrical resistivity of Pd43Ni10Cu27P20 bulk metallic glass during a constant heating process. The results of electrical resistivity suggest that the position of the internal friction peak is the onset temperature of crystallization. The dependence of internal friction on frequencies show both linear and nonlinear relations. The internal friction at 623 K in the supercooled liquid region decreases monotonously with the increase of annealing time, indicating structural relaxation and subsequent crystallization occurs during isothermal annealing near the crystallization temperature. (© 2007 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim) [source] | |||||||||||||