Local atomic structure in al-re marginal metallic glasses

Download

index.pdf

Date

2016

Author

Övün, Mert

Metadata

Show full item record

Item Usage Stats

300
views

118
downloads

Partial devitrification of the Al-RE marginal metallic glasses results in anomalous nucleation rate of nanocrystals conflicting with the classical nucleation theory by several orders of magnitude. One of the theoretical approaches explaining this phenomenon is the medium-range order (MRO) structures within the range of 1-2 nm that may be present both in the quenched amorphous state and its liquid precursor. In this work, these structures have been investigated conducting both experimental methods such as high energy X-ray diffraction (HEXRD) using synchrotron radiation, and computational methods as molecular dynamics (MD) , Monte Carlo (MC) and reverse Monte Carlo (RMC) simulation techniques. In order to make molecular simulations, interatomic potentials based on diffraction experiments have been developed. This work was partially supported by the Scientific and Technological Research council of Turkey (TÜBİTAK) under Grant No. 113M346.

Subject Keywords

Alloys., Rhenium., Metallic glasses., Metallic composites., Amorphous substances.

URI

http://etd.lib.metu.edu.tr/upload/12620103/index.pdf
https://hdl.handle.net/11511/25746

Collections

Graduate School of Natural and Applied Sciences, Thesis

Suggestions

OpenMETU
Core

Raman Frequencies calculated as a function of pressure for the rotatory lattice mode in ammonia solid II near the melting point Yurtseven, Hasan Hamit (2004-04-01) This study gives our calculations for the Raman frequencies of the rotatory lattice mode in ammonia solid II near the melting point. The Raman frequencies of this mode are calculated as a function of the pressure using the volume data for the fixed temperatures of 230.4 K, 263.4 K, and 297.5 K by means of our Gruneisen relation. Our calculated frequencies can be examined experimentally when the Raman measurements are performed at various pressures for the constant temperatures considered.
Local chemical and topological order in Al-Tb and its role in controlling nanocrystal formation Kalay, Yunus Eren; HWANG, Jinwoo; VOYLES, P. M.; KRAMER, M. J. (2012-02-01) How the chemical and topological short- to medium-range order develops in Al-Tb glass and its ultimate effect on the control of the high number density of face-centered-cubic-Al (fcc-Al) nuclei during devitrification are described. A combined study using high-energy X-ray diffraction (HEXRD), atom probe tomography (APT), transmission electron microscopy and fluctuation electron microscopy (FEM) was conducted in order to resolve the local structure in amorphous Al90Tb10. Reverse Monte Carlo simulations and V...
Thermal characterization of different origin class-G cements Kök, Mustafa Verşan (2014-02-01) In this study, thermal characteristics and kinetics of three different origin class-G cements (Mix, Bolu, and Nuh) were studied using thermogravimetry (TG/DTG) and differential scanning calorimeter (DSC). In DSC curves at different heating rates a number of peaks were observed consistently in different temperature intervals. TG/DTG is used to identify the detected phases and the corresponding mass loss. In the dehydration kinetic study of the different origin class-G cement samples, three different methods ...
Fourth generation effects in rare exclusive B -> K*l(+)l(-) decay Alıyev, Tahmasıb; Özpineci, Altuğ; Savcı, Mustafa (2000-10-02) Influence of the fourth generation, if ever exists, on the experimentally measurable quantities such as invariant dilepton mass distribution, lepton forward-backward asymmetry, and the ratio Gamma(L)/Gamma(T) of the decay widths when K* meson is longitudinally and transversally polarized, is studied. Using the experimental results on the branching ratios for the B --> X(s)gamma and semileptonic B --> X(c)l (v) over bar decays, the two possible solutions of the 4 x 4 Cabibbo-Kobayashi-Maskawa factor Vt'sVt'b...
Nanocrystallization in marginal glass forming alloys Demirtaş, Tuba; Kalay, Yunus Eren; Department of Metallurgical and Materials Engineering (2013) The marginal glass-forming alloys have attracted much attention due to unique products of devitrification with a very high number density of nuclei up to 10^23 m^-3. Among these alloy systems, utmost interest is given to Al-RE and Al-TM-RE alloys with excellent lightweight mechanical (fracture strength close to 1 GPa) and chemical properties attributed to the presence of an extremely high density of nanocrystals embedded in an amorphous matrix. Classical nucleation theory fails in explaining this abnormal n...

Citation Formats

M. Övün, “Local atomic structure in al-re marginal metallic glasses,” M.S. - Master of Science, Middle East Technical University, 2016.