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Search Results: 1 - 10 of 964 matches for " Solidification "
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Heat Transfer Analysis during External Chilling of Composite Material Castings through Experimental and Finite Element (FE) Modelling  [PDF]
Joel Hemanth
Modeling and Numerical Simulation of Material Science (MNSMS) , 2014, DOI: 10.4236/mnsms.2014.41001
Abstract:
In controlled solidification, one of the important factors that affects heat transfer from the solidifying casting is the resistance offered at the casting/chill interface. In the present investigation, heat transfer analysis during solidification of Al-12%Si (LM 13) alloy is carried out by collecting temperature history of the solidifying casting. The temperature distribution during solidification in the present investigation is obtained using ANSYS multiphysics software and further for comparison. The temperature profiles are also obtained by FE (Finite Element) modelling using the same software. By using a temperature data logger and lab view based software, the temperature data is acquired and processed at every second. The cooling curves obtained are analysed to know the effect of chilling on solidification behaviour of Al-12%Si alloy castings. Finally, it is concluded from the above research that the cooling curves and temperature distribution obtained by FE analysis do not so closely converge with the experimental data due to modelling limitations.
Simulation of Solidification Parameters during Zr Based Bulk Metallic Glass Matrix Composite’s (BMGMCs) Additive Manufacturing  [PDF]
Muhammad Musaddique Ali Rafique
Engineering (ENG) , 2018, DOI: 10.4236/eng.2018.103007
Abstract: After a silence of three decades, bulk metallic glasses and their composites have re-emerged as a competent engineering material owing to their excellent mechanical properties not observed in any other engineering material known till date. However, they exhibit poor ductility and little or no toughness which make them brittle and they fail catastrophically under tensile loading. Exact explanation of this behaviour is difficult, and a lot of expensive experimentation is needed before conclusive results could be drawn. In present study, a theoretical approach has been presented aimed at solving this problem. A detailed mathematical model has been developed to describe solidification phenomena in zirconium based bulk metallic glass matrix composites during additive manufacturing. It precisely models and predicts solidification parameters related to microscale solute diffusion (mass transfer) and capillary action in these rapidly solidifying sluggish slurries. Programming and simulation of model is performed in MATLAB®. Results show that the use of temperature dependent thermophysical properties yields a synergic effect for multitude improvement and refinement simulation results. Simulated values proved out to be in good agreement with prior simulated and experimental results.
Modelling and Simulation of Solidification Phenomena during Additive Manufacturing of Bulk Metallic Glass Matrix Composites (BMGMC)—A Brief Review and Introduction of Technique  [PDF]
Muhammad Musaddique Ali Rafique
Journal of Encapsulation and Adsorption Sciences (JEAS) , 2018, DOI: 10.4236/jeas.2018.82005
Abstract: Despite a wealth of experimental studies focused on determining and improving mechanical properties and development of fundamental understanding of underlying mechanisms behind nucleation and growth of ductile phase precipitates from melt in glassy matrix, still, there is dearth of knowledge about how these ductile phases nucleate during solidification. Various efforts have been made to address this problem such as experiments in microgravity, high resolution electron microscopy and observation in synchrotron light after levitation but none have proved out to be satisfactory. In this study, an effort has been made to address this problem by modelling and simulation. Current state of the art of development, manufacturing, characterisation and modelling and simulation of bulk metallic glass matrix composites is described in detail. Evolution of microstructure in bulk metallic glass matrix composites during solidification in additive manufacturing has been presented with the aim to address fundamental problem of evolution of solidification microstructure as a result of solute partitioning, diffusion and capillary action. An overview is also presented to explain the relation of microstructure evolution to hardness and fracture toughness. This is aimed at overcoming fundamental problem of lack of ductility and toughness in this diverse class of materials. Quantitative prediction of solidification microstructure is done with the help of advanced part scale modelling and simulation techniques. It has been systematically proposed that 2-dimensional cellular automaton (CA) method combined with finite element (for thermal modelling) tools (CA-FE) programmed on FORTRAN and parallel simulated on ABAQUS would best be able to describe this complicated multiphysics phenomenon in most efficient way. Focus is laid on quantification of methodology by which modelling and simulation can be adopted and applied to describe evolution of microstructure in this important class of materials. It is found that proposed methodology is meritorious.
Effect of Heat Treatment on Mechanical Properties of Al-1.5Cu-9.5Zn-3Mg Rapidly Solidified Alloy  [PDF]
El Said Gouda, Emad Makboul Ahmed, Nabih Lotfi Tawfik
Materials Sciences and Applications (MSA) , 2010, DOI: 10.4236/msa.2010.14031
Abstract: Ribbons with the composition Al-1.5Cu-9.5Zn-3Mg were prepared by melt spinning technique. Microhardness and tensile strength were measured. The melt spun hardness and ultimate tensile strength values were as high as 291 HV and 660 MN/m2, respectively. Hardness values are relaxed to lower values on prolonged thermal annealing to around 50%. X-ray diffraction lines corresponding to Cu, Zn and Mg were disappeared for the as melt spun ribbons, which indicates a complete solubility of these element in Al matrix. On prolonged thermal annealing these alloying elements were precipitated.
Numerical Investigation of Bismuth Unloading Solidification with Abnormal Melting Characteristic  [PDF]
Jingsong Bai, Jidong Yu, Tao Wang
World Journal of Mechanics (WJM) , 2014, DOI: 10.4236/wjm.2014.47021
Abstract:

We present the processes and results of a numerical investigation of the bismuth unloading solidification by a graded density impactor, and demonstrate that the physical process may be realized due to bismuth abnormal melting characteristics. A more reasonable high-pressure solid equation of state of the fifth phase bismuth is introduced in our calculation and one type of graded density impactor made of 15 compositions of Mg-Cu material system is given in this paper. We detailedly investigate one possible proposed approach to achieve the unloading solidification physical process, and our numerical analysis on the thermodynamic state, the unloading path and the phase transformations.

Preparation and Structural Characterization of Vanadium Doped Ni – B Binary Hard Alloys  [PDF]
J. A. Ajao
Journal of Minerals and Materials Characterization and Engineering (JMMCE) , 2010, DOI: 10.4236/jmmce.2010.96040
Abstract: The microstructure of a series of binary Ni-B alloys containing various amounts of vanadium additions were investigated by Differential Thermal Analysis (DTA), Scanning Electron Microscopy (SEM), Transmission Electron Microscopy (TEM) and Energy Dispersive X-ray Analysis (EDXA). Due to the vanadium addition in the alloys quenched from the liquidus, the formation of the Ni3B phase was enhanced even when the nominal composition was hypoeutectic. The addition of vanadium led to the formation of t (Ni20.4V2.6B6) phase during the present investigation. In addition, the crystallographic orientation relationship of this ternary phase with the nickel matrix was reported. The solid-state eutectoid transformation of the Ni3B phase during cooling was also reported and discussed.
Solidification and Structuresation of Instability Zones  [PDF]
Evgeniy Alexseevich Lukashov, Evgeniy Vladimirovich Radkevich
Applied Mathematics (AM) , 2010, DOI: 10.4236/am.2010.13021
Abstract: Two mathematical crystallization models describing structure formations in instability zones are proposed and justified. The first model, based on a phase field system, describes crystallization processes in binary alloys. The second model, based on a modified Biot model of a porous medium and the convective Cahn–Hilliard model, governs oriented crystallization. Physical interpretation and numerical analysis are discussed.
Fabrication and Corrosion Behaviour of Aluminium Alloy (LM-13) Reinforced with Nano-ZrO2 Particulate Chilled Nano Metal Matrix Composites (CNMMCs) for Aerospace Applications  [PDF]
Joel Hemanth, M. R. Divya
Journal of Materials Science and Chemical Engineering (MSCE) , 2018, DOI: 10.4236/msce.2018.67015
Abstract: This research presents the results obtained and the discussions made from a series of corrosion experiments involving aluminum alloy (LM 13) reinforced with Nano-ZrO2, size of the particles dispersed varies from 100 - 200 nm and amount of addition varies from 3 wt% to 15 wt% in steps of 3 wt%. The resulting CNMMCs are solidified under the influence of copper chill of 25 mm thickness to study the effect of corrosion behavior. The corrosion test employed was the electrochemical polarization method according to ASTM G59-97 (2009) standards. Corrosion resistance was found to increase significantly with increase inZrO2 content in chilled CNMMCs. Nevertheless, even with high ZrO2 content corrosion attack i.e., pitting was found to be most severe during the initial stages of each test but it invariably decreased to a very low value in the later stages, due to the formation of an adherent protective layer on the CNMMCs developed. SEM studies of the corroded surface were also examined to study the mechanism of corrosion. Present research is undertaken to develop a corrosion resistant composite for aerospace application where aluminum is highly suspected to corrosion.
Solidifica??o direcional do eutético Al2O3/GdAlO3 por fus?o a laser
Andreeta, E. R. M.;Rodrigues, J. A.;Andreeta, M. R. B.;Agulló-Rueda, F.;Hernandes, A. C.;
Ceramica , 2002, DOI: 10.1590/S0366-69132002000100007
Abstract: pore-free eutectic fibers of al2o3/gdalo3 were produced by the laser melting technique named lhpg. the "chinese script" microstructure was observed using scanning electron microscopy. fibrous pattern could be found in some of the samples. microraman spectroscopy could index the eutectic phases and showed the continuity of the fibrous gdalo3 when compared to the "chinese script" pattern. three points bending measurements resulted in values of modulus of rupture varying from 490 mpa to 1316 mpa.
Identification of the heat transfer coefficient in phase change problems
Damian S ota
Archives of Thermodynamics , 2010, DOI: 10.2478/v10173-010-0004-y
Abstract: In this paper, an algorithm will be presented that enables solving the two-phase inverse Stefan problem, where the additional information consists of temperature measurements in selected points of the solid phase. The problem consists in the reconstruction of the function describing the heat transfer coefficient, so that the temperature in the given points of the solid phase would differ as little as possible from the predefined values. The featured examples of calculations show a very good approximation of the exact solution and stability of the algorithm.
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