Theoretical and experimental investigation of bulk glass forming ability in bulk amorphous alloy systems

Download

index.pdf

Date

2005

Author

Ayas, Can

Metadata

Show full item record

Item Usage Stats

261
views

152
downloads

In this study molecular dynamics simulation program in NVT ensemble using Velocity Verlet integration was written in order to investigate the glass forming ability of two metallic systems. The Zn-Mg system, one of the frontiers of simple metal-metal metallic glasses and Fe-B, inquiring attention due to presence of many bulk glass forming alloy systems evolved from this binary with different alloying element additions. In addition to this, atomistic calculations on the basis of ordering were carried out for both Zn-Mg and Fe-B systems. Ordering energy values are calculated using electronic theory of alloys in pseudopotential approximation and elements which increase the ordering energy between atoms were determined. The elements which increase the ordering energy most were selected as candidate elements in order to design bulk amorphous alloy systems. In the experimental branch of the study centrifugal casting experiments were done in order to see the validity of atomistic calculations. Industrial low grade ferroboron was used as the master alloy and pure element additions were performed in order to constitute selected compositions. Fe62B21Mo5W2Zr6 alloy was successfully vitrified in bulk form using nearly conventional centrifugal casting processing. Specimens produced were characterized using SEM, XRD, and DSC in order to detect the amorphous structure and also the crystalline counterpart of the structure when the cooling rate is lower. Sequential peritectic and eutectic reaction pattern was found to be important for metallic glasses which can be vitrified in bulk forms with nearly conventional solidification methods.

Subject Keywords

Metallurgy.

URI

http://etd.lib.metu.edu.tr/upload/12605884/index.pdf
https://hdl.handle.net/11511/14815

Collections

Graduate School of Natural and Applied Sciences, Thesis

Suggestions

OpenMETU
Core

Investigation of fracture behavior of steel/steel laminates Şimşir, Mehmet; Öztürk, Tayfur; Department of Metallurgical and Materials Engineering (2004) A study is carried out into fracture behavior of steel/steel laminates both experimentally and through finite element analysis (FEM). The laminates produced by hot pressing consisted of low carbon and medium carbon steels with two volume fractions; 0.41 and 0.81. Fracture toughness, JIC has been measured using partial unloading technique assuming a critical value of crack extension. The technique is initially applied to monolithic material and then to the laminates in crack divider orientation. Evaluation o...
Microstructural characterization of hypoeutectoid steels quenched from the Ae1 - Ae3 intercritical temperature range by magnetic barkhausen noise technique Boyacıoğlu, Beril; Gür, Cemil Hakan; Department of Metallurgical and Materials Engineering (2006) This thesis aims to examine the possibility of using Magnetic Barkhausen Noise technique in characterizing the ferritic-martensitic microstructure of hypoeutectoid steels quenched from the intercritical temperature range. For this purpose, rectangular specimens were prepared from SAE 1020, 1040 and 1060 steels. The specimens were heated at different temperatures within the intercritical temperature range and then quenched into water. Microstructures of the specimens were characterized by metallographic exam...
An investigation of the microstructural and mechanical properties of tri-calcium phosphates doped with aluminum and fluoride ions Tahmasebifar, Aydin; Evis, Zafer; Department of Engineering Sciences (2011) The aim of this study was to investigate the microstructure and mechanical properties of pure tricalcium phosphate (TCP) and tricalcium phosphates doped with aluminum (Al3+) and fluoride (F-) ions at different compositions. TCP was synthesized via precipitation method and sintered at 1100C for 1 and 5 h. It was observed that density and relative density of the sintered materials were decreased by extending the sintering time. Increased densities were achieved upon Al3+ and/or F- doping. For structural anal...
Investigation of the effect of orientation and heat treatment on the stress corrosion cracking susceptibility of 7050 aluminium alloy Çevik, Gül; Doruk, Mustafa; Department of Metallurgical and Materials Engineering (2004) In the present work, the effect of variation in specimen orientation and heat treatment on the Stress Corrosion Cracking (SCC) susceptibility of 7050 aluminum alloy was investigated in 3,5% NaCl solution and under freely corroding conditions. For this purpose, Constant Extension Rate Tests (CERT) was performed on precracked Compact Tension (CT) specimens and the Direct Current Potential Drop technique was applied to measure the crack lengths. In addition to crack length versus time curves, the relationship ...
Microstructural and elecrochemical characterization of Ti-6A1-4V ELI alloy Topçuoğlu, Melih; Aydınol, Mehmet Kadri; Department of Metallurgical and Materials Engineering (2006) In this study, the evolution of structure and the relationship between microstructure and corrosion behavior of the Ti-6Al-4V ELI (Extra Low Interstitial) alloy was investigated in Ringer’s solution at 37 ± 0.1 oC. Initially, different heat treatments were performed in order to obtain several microstructures which were; Widmanstätten α for furnace cooling (FC), basket-weave α for air cooling (AC), martensite (α') for water quenching (WQ) from 1060 oC, and aged martensite for ten hours at 500, 600, 700, 800,...

Citation Formats

C. Ayas, “Theoretical and experimental investigation of bulk glass forming ability in bulk amorphous alloy systems,” M.S. - Master of Science, Middle East Technical University, 2005.