No description available.

In this study, two semi-analytical models of microsegregation were developed to predict the concentration fields of solute in the liquid and solid regions for dendritic solidification of binary metallic alloys. Both models assume that the growing dendrites are cylindrical in shape. This assumption is more realistic compared to the common assumptions of plate-like dendrites that most of the earlier researchers employed in their microsegregation modeling study. The solute redistribution profile, in the developing solid layer, necessary to determine the back diffusion parameter was derived from Fick's second law for the model without coarsening. The application of this parameter in a wide range of conditions and the use of its basic form in the model with coarsening was verified. The concept of coordinate transformation and enhancement of back-diffusion Fourier number were used in deriving the model which took into account the coarsening of dendrites. The models are then extended to deal with rapid solidification, peritectic transformations and multi-component systems and the results were compared with relevant experimental data. A good agreement between the model predictions and experimental results was found. / The second part of this study was focused on developing a fully numerical microsegregation model. The numerical model built upon a previously proposed phase change model which relied upon a coordinate transformation technique. The model was extended to deal with moving boundaries with solute diffusion. A suitable computational procedure was developed to solve the model equations which are strongly coupled to each other. To verify the accuracy of the present algorithm with regard to the capability of tracking the moving interfaces, analytical solution of the Stefan problem was used for verification purposes. A good agreement between the model predictions and the analytical solution was found. Evolution of concentration fields during solidification was calculated in the growing solid as well as in the shrinking liquid regions for rectangular, cylindrical and spherical dendrite geometries. The effects of various cooling conditions and relevant parametric values on microsegregation were analyzed and discussed.

Significant reductions in the number of defects in parts produced by investment casting can be obtained by improving the flow of the molten metal during pouring. Studies have been done at Oregon State University with simulated casting techniques to determine optimal mold configurations. Better mold layouts have been shown to improve this flow. The purpose of this project was to develop a computer imaging system that would aid in reliably evaluating these experiments. The completed system consisted of a computer, a frame grabber, video equipment and operating software. Videotapes made of the fluid flow in the mold during the pouring process were replayed into the computer and evaluated. Custom software reduced the collected data to a representative evaluation number. Results show that the computer evaluations are reliable and reproducible, but applications are limited because of the cost, speed and power of available computer systems. / Graduation date: 1994

Thesis (M.S.)--Cleveland State University, 2008. / Abstract. Title from PDF t.p. (viewed on July 3, 2008). Includes bibliographical references (p.56-57). Available online via the OhioLINK ETD Center. Also available in print.

Thesis (Ph. D.)--University of Alabama at Birmingham, 2007. / Title from PDF of title page (viewed October 13, 2009). Additional advisors: J. Barry Andrews, Gregg M. Janowski, Peter M. Walsh, Srinath Viswanathan, Harry E. Littleton. Includes bibliographical references (p. 207-209).

Thesis (MScIng)--University of Stellenbosch, 2008. / Bibliography. Also available via the Internet.

Thesis (MTech (Mechanical Engineering))--Cape Peninsula University of Technology, 2010. / The research presented in this report focuses on Investment Casting capabilities for light metal alloys in South Africa and forms part of the Advanced Manufacturing Technology Strategy's (AMTS): Light Weight Metals flagship programme. The research is centred on the suitability of rapid prototyping (RP)/Iayer manufacturing (LM) methods to produce patterns for the investment casting of aluminium (AI), magnesium (Mg) and titanium (Ti) alloys, together known as Rapid Investment Casting. Three core RP technologies are investigated namely: Three Dimensional Printing - Drop-on-Bed from Z-corporation, Three Dimensional Printing - Drop-on- Drop from ThermoJet - 3D Systems and Selective Laser Sintering from EOS. Various RP/LM processes are discussed in detail and highlight the technologies selected in this study. A standard benchmark part, adapted from the European project framework FP6, designed and utilised in similar studies is used as the basis for the research. The Investment Casting process is discussed fully and compared to the Rapid Investment Casting, listing both the advantages and disadvantages of the above mentioned methods. In addition a special study has been conducted on investment casting of large components using layer manufactured patterns. This study not only helped to establish and validate the shrinkage value calculated for the aluminium castings but also showed substantial capability lacks in SA foundries to handle this type of components, which are by definition most often of high added value.

No description available.

Thesis. 1977. Ph.D.--Massachusetts Institute of Technology. Dept. of Electrical Engineering and Computer Science. / MICROFICHE COPY AVAILABLE IN ARCHIVES AND ENGINEERING. / Bibliography : p. 185-189. / by Robert J. Woodham. / Ph.D.

Thesis (M.S.)--Worcester Polytechnic Institute. / Keywords: thixocasting; SSM; semi-solid processing; liquid metal mixing; rheocasting. Includes bibliographical references (p. 88-90).