The aim of this study is to synthesize and characterize new bulk amorphous alloys in the Ni- based systems. Theoretical studies on the basis of semi-empirical rules and the electronic theory of alloys in pseudopotential approximation has been provided in order to predict the impurity elements that will lead to an increase in the glass forming ability of Ni-based alloy systems. Glass forming ability of ten different compositions of alloys of Ni-Nb, Ni-Fe, Ni-B, Ni-Hf and Ni-Cr was simulated by using FORTRAN programs based on pseudopotential theory. In addition to the binary alloys, ternary alloys, which were formed by addition of 1 at% of third element to these systems, were also simulated. Since ordering energy is an indicator of glass forming ability, theoretical studies allowed to predict the effect of various third elements on the formation of amorphous phase. Furthermore, ordering energies were also used to calculate other parameters important for glass forming ability. In the second part of the study, on the basis of theoretical results, a series of casting experiments were done. Different compositions of Ni-Nb, Ni-Nb-Sn and Ni-Nb-Al alloys were cast in the centrifugal casting machine. Alloys were melted in alumina crucibles and cast into the copper moulds. Characterizations of cast alloys were done by the use of Metallography, SEM, XRD and DSC. Fully amorphous Ni52Nb41Al7 alloy was synthesized in bulk form with 0.8 mm thickness.
| Identifer | oai:union.ndltd.org:METU/oai:etd.lib.metu.edu.tr:http://etd.lib.metu.edu.tr/upload/3/12605099/index.pdf |
| Date | 01 June 2004 |
| Creators | Arslan, Hulya |
| Contributors | Mekhrabov, Amdulla O. |
| Publisher | METU |
| Source Sets | Middle East Technical Univ. |
| Language | English |
| Detected Language | English |
| Type | M.S. Thesis |
| Format | text/pdf |
| Rights | To liberate the content for public access |
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