Experimental Determination of Material Properties for Modelling Solidification Cracking
Digital Document
Document
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http://hdl.handle.net/11134/20002:860707128
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Persons |
Persons
Creator (cre): Narayan, Lakshmi Ravi
Major Advisor (mja): Hebert, Rainer
Associate Advisor (asa): Brody, Harold
Associate Advisor (asa): Alpay, Pamir
Associate Advisor (asa): Frame, Lesley
Associate Advisor (asa): Lee, Seok-Woo
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Title |
Title
Title
Experimental Determination of Material Properties for Modelling Solidification Cracking
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Origin Information
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Parent Item
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Digital Origin |
Digital Origin
born digital
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Description |
Description
The effort to speed up the design of alloys and processing methods with the use of computer simulations requires reliable input data. The input to these models, which are the properties and behavior of materials, must consider the conditions under which the processes take place. This work addresses the need for such data that would be required to model and predict the occurrence of cracking during rapid solidification processes. A solidification crack in a metal alloy is the result of the competition between the solid phase that is growing at the expense of the diminishing liquid phase, which is also thermally contracting and imposing a mechanical strain upon itself, and the remaining liquid phase flowing into any cracks and voids that might have formed as a result of the thermal straining. The inputs to a solidification cracking model are thus the rate of solidification, represented as a fraction of solid curve, the thermomechanical properties of the solid phase and the viscosity of the liquid phase. These vary with the composition of the alloy and temperature. During solidification of a metal alloy, the distribution of the solute in the microstructure is not homogeneous and varies with the speed of solidification. Determining this degree of microsegregation at rapid solidification rates was a first step in this work, as it informs at what composition the other inputs need to be taken in the model. Available theoretical models were compared with laser-glazing experiments. Secondly, chip-based fast scanning calorimetry was used to determine the fraction of solid curves under rapid cooling rates up to 40,000 °Cs-1. The data from calorimetry was also used to plot a kinetic phase diagram. Thirdly, oscillatory rheology was used to characterise the thermomechanical behaviour of partially solidified metal alloys. It was also shown that oscillatory rheology is better suited for partially solid materials than the more commonly used rotational viscometry. Finally, this document concludes with a note on how the data generated in this work can be used in the modelling of rapid solidification processes to predict the occurrence of cracks.
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Organizations
Degree granting institution (dgg): University of Connecticut
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Use and Reproduction |
Use and Reproduction
These Materials are provided for educational and research purposes only.
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Note |
Note
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Degree Name |
Degree Name
Doctor of Philosophy
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Degree Level |
Degree Level
Doctoral
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Degree Discipline |
Degree Discipline
Materials Science and Engineering
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Local Identifier |
Local Identifier
S_32175879
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