Rapid Solidification Processing of High Temperature and Reactive Alloys
Sears, James William
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https://hdl.handle.net/2142/70154
Description
Title
Rapid Solidification Processing of High Temperature and Reactive Alloys
Author(s)
Sears, James William
Issue Date
1988
Doctoral Committee Chair(s)
Fraser, Hamish L.
Department of Study
Mechanical Engineering
Discipline
Mechanical Engineering
Degree Granting Institution
University of Illinois at Urbana-Champaign
Degree Name
Ph.D.
Degree Level
Dissertation
Keyword(s)
Engineering, Mechanical
Engineering, Metallurgy
Engineering, Materials Science
Abstract
An experimental study has been undertaken to develop the technology for producing high temperature and reactive metal alloys through rapid solidification processing (RSP). An empirical approach has been used to develop these processes. Several unique configurations of melting and quenching have been evaluated. Induction, DC-arc and plasma have been considered for initial melting of these alloys. Centrifugal atomization and melt-spinning have been evaluated as means of rapid quenching. Several alloys of Ti and Nb were selected because of the current interest in the aerospace community in their development. Rare-earth oxide dispersions were formed in Ti alloys with Al content ranging from 0 to 50 at.%. Several intermetallic alloys were studied, such as Ti$\sb3$Al, TiAl, Ti$\sb5$Si$\sb3$, TiB$\sb2$ and TiC. The effects of RSP on Nb alloys with additions of Al and Si were also studied. Standard chemical analysis was used to evaluate the chemical uniformity and purity of the alloys in the RSP condition. These analyses were used to evaluate the effectiveness of the process involved. Microscopic analysis was performed on each alloy through the use of transmission electron microscopy (TEM), scanning electron microscopy (SEM) and optical microscopy to determine the effects of RSP on microstructure. Powder and ribbon produced through RSP were analyzed in the assolidified state and following thermal treatments to determine the extent of undercooling and microstructural modifications.
This investigation has shown that high temperature and reactive alloys can be processed in a controlled environment to produce unique and useful microstructures through RSP. The development of these alloys through RSP may some day lead to advances in other areas of engineering. It is anticipated that this study will provide some useful information for further development in rapid solidification technology.
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