Solidification and crystallization behaviour of bulk glass forming alloys

Download

index.pdf

Date

2007

Author

Aybar, Sultan

Metadata

Show full item record

Item Usage Stats

270
views

109
downloads

The aim of the study was to investigate the crystallization kinetics and solidification behaviour of Fe60Co8Mo5Zr10W2B15 bulk glass forming alloy. The solidification behaviour in near-equilibrium and non-equilibrium cooling conditions was studied. The eutectic and peritectic reactions were found to exist in the solidification sequence of the alloy. The bulk metallic glass formation was achieved by using two methods: quenching from the liquid state and quenching from the semi-state. Scanning electron microscopy, x-ray diffraction and thermal analysis techniques were utilized in the characterization of the samples produced throughout the study. The choice of the starting material and the alloy preparation method was found to be effective in the amorphous phase formation. The critical cooling rate was calculated as 5.35 K/s by using the so-called Barandiaran and Colmenero method which was found to be comparable to the best glass former known to date. The isothermal crystallization kinetics of the alloy was studied at temperatures chosen in the supercooled liquid region and above the first crystallization temperature. The activation energies for glass transition and crystallization events were determined by using different analytical methods such as Kissinger and Ozawa methods. The magnetic properties of the alloy in the annealed, amorphous and as-cast states were characterized by using a vibrating sample magnetometer. The alloy was found to have soft magnetic properties in all states, however the annealed specimen was found to have less magnetic energy loss as compared to the others.

Subject Keywords

Thermal Analysis.

URI

http://etd.lib.metu.edu.tr/upload/12608922/index.pdf
https://hdl.handle.net/11511/17013

Collections

Graduate School of Natural and Applied Sciences, Thesis

Suggestions

OpenMETU
Core

Solidification behaviour of bulk glass-forming alloy systems Akdeniz, Mahmut Vedat; Mehrabov, Amdulla (Elsevier BV, 2005-1) The solidification behaviour and resultant microstructures of bulk glass forming ferrous (Fe60CoSZr10Mo5W2B15) and non-ferrous (Zr65Al10Ni10Cu15) alloy systems have been investigated. It was shown that the suppression of the eutectic reaction during solidification ultimately leads to the formation of an amorphous structure. The characteristic DSC pattern of melting involving a sequence of eutectic and pefitectic like reactions with a high inapitude of reaction enthalpies ratio (AHp/AH,). appear to be essent...
Solidification behavior, glass forming ability and thermal characteristics of soft magnetic Fe-Co-B-Si-Nb-Cu bulk amorphous alloys AYKOL, Muratahan; Akdeniz, Mahmut Vedat; Mehrabov, Amdulla (2011-09-01) The effect of varying Cu content on the bulk glass forming ability (GFA) of (Fe(0.36)Co(0.36)B(0.192)Si-(0.048)Nb(0.04))(100-X)Cu(X) alloys (X = 0, 0.5, 0.75 and 1.0) is revealed by investigating the thermal behaviors and phase competitions upon solidification. The changes in GFA are interpreted in terms of suppression of consecutive solidification reactions via microstructural and thermal features. Instead of the type of the primary crystallization product originating from the prevalent atomic order in the...
Calorific value determination of coals by DTA and ASTM methods. Comparative study Kök, Mustafa Verşan (2001-08-20) This research comprises the applicability of complex thermal analysis technique (TG/DTG, DTA) in the determination of calorific values of coals of different origin. The calorific values, those obtained by thermal analysis are compared with an adiabatic bomb calorimeter by the standard ASTM method, and the results are discussed.
Thermal and geochemical investigation of Seyitomer oil shale Kök, Mustafa Verşan; Hufnagel, Heinz; Sonel, Nurettin (Elsevier BV, 2001-4) The results of an experimental study on the thermal and organic geochemical investigation of Seyitomer oil shale sample are presented. Thermogravimetry (TG/DTG) and differential scanning calorimetry (DSC) have been used to determine the thermal behaviour of the oil shale sample. On the other hand, organic carbon content, rock-eval pyrolysis, and gas and liquid chromatography experiments were conducted to determine geochemical properties of the oil shale sample.
Numerical analysis of temperature distribution of superconducting coil stack İnanır, Fedai; Bak, Bekir; Yıldız, Şükrü; Keysan, Ozan (null; 2017-11-04) In this study, magneto-thermal studies were carried out by solving Ampere and heat conduction equations together in superconducting coil stacks wounded by coated conductors. The coil stack used in the calculations consists of 4 bobbins in the solenoidal structure and each bobbin has 100 windings. Coated conductors are 12mm in width, 100 µm in thickness and has 100 A critical current density. The two-dimensional temperature distributions of the coil stack for different current amplitudes were obtained. The e...

Citation Formats

S. Aybar, “Solidification and crystallization behaviour of bulk glass forming alloys,” M.S. - Master of Science, Middle East Technical University, 2007.