Synthesis and characterization of copper based bulk amorphous alloys

Erdem, Mermer
Copper based bulk metallic glasses (BMG’s) are one of the promising advanced materials due to their unique mechanical properties, high glass forming ability (GFA) and low cost. In this thesis, the aim is to synthesize Cu-Hf based BMG’s and to investigate the crystallization behavior. Moreover, the crystallization kinetics by means of activation energies, critical cooling rate, nanocrystallization and Avrami exponents have been studied. Cu70Hf30 and Cu50Hf50 binary alloys were produced via arc melting with suction casting unit. However, amorphous structure could not be achieved because of the necessity of lower free energy arose from higher entropy. Therefore, aluminum was added to Cu-Hf system to stabilize the melt and to increase GFA which allowed producing amorphous samples.Thermal analysis studies showed that GFA parameters such as Trg, ΔTx are in good agreement with the results reported in the literature. It was observed that Cu49Hf42Al9 ternary alloy solidifies through eutectic reaction at 910 ºC under near equilibrium conditions. However, it was shown that suppression of this eutectic reaction under non-equilibrium cooling conditions lead to the formation of an amorphous phase. The critical cooling rate required for the suppression of the eutectic reaction was determined as 1.25 K/s by isochronal crystallization kinetics. Annealing of these amorphous samples at temperatures around Tx lead to single stage crystallization of CuHf2nanocrystals with an average size of about 20 nm.The average Avrami exponent value was estimated to be 2.3 implying the crystallization process was governed by diffusion controlled three-dimensional growth with decreasing nucleation rate.


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Amorphous and bulk amorphous metallic alloys are an intriguing class of structural materials and possess a range of interesting properties, including near theoretical strength, high hardness, extremely low damping characteristics, excellent wear properties, high corrosion resistance, low shrinkage during cooling and almost perfect as-cast surfaces with good potential for forming and shaping. In this study, new Ti-based bulk amorphous alloys are tried to be modeled and synthesized. For that purpose, electron...
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Sıkan, Fatih; Kalay, Yunus Eren; Kalay, İlkay; Department of Metallurgical and Materials Engineering (2017)
Bulk metallic glasses have recently attracted much attention due to their high mechanical strength both in amorphous and in the amorphous/nanocrystal composite form along with their high glass forming ability. However, factors such as having a low plastic strain limit their potential application as structural materials. In this present work, ternary (Zr50Cu40Al10)100–xSmx (x:0-4 at. %) amorphous alloys were produced by melt-spinning in ribbon form and suction casting in bulk form within the diameter range o...
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Saltoğlu, İlkay; Akdeniz, Mahmut Vedat; Mehrabov, Amdulla (2005-09-28)
In recent years, bulk amorphous alloys and nanocrystalline materials have been synthesized in a number of ferrous and non-ferrous based alloys systems, which have gained some applications due to their unique physico-chemical and mechanical properties. In the last decade, Zr-based alloys with a wide supercooled liquid region and excellent glass forming ability have been discovered. These systems have promising application fields due to their mechanical properties; high tensile strength, high fracture toughne...
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Abboud, Mohammad; Özerinç, Sezer; Kalay, Yunus Eren; Department of Micro and Nanotechnology (2018)
Amorphous/crystalline nanolayers provide an effective model system to study the mechanical behavior and size effects of metallic glasses and crystalline metals in confined geometries. They also provide an advantageous structure for improving the ductility of amorphous metals while maintaining their outstanding strength. Combination of high strength and ductility make these nanocomposites promising materials as wear resistant coatings. The structure-property relationship in Amorphous/Crystalline nanolayers c...
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Erdiller, Emrah Salim; Akdeniz, Mahmut Vedat; Department of Metallurgical and Materials Engineering (2004)
The aim of this study is to form a theoretical model for simulation of glass forming ability of Fe ? Based bulk amorphous alloys, to synthesize Fe ? based multicomponent glassy alloys by using the predictions of the theoretical study, and to analyze the influence of crystallization and solidification kinetics on the microstructural features of this amorphous alloys. For this purpose, first, glass forming ability of Fe ? (Mo, B, Cr, Nb, C) ? X ( X = various alloying elements, selected from the periodic table...
Citation Formats
M. Erdem, “Synthesis and characterization of copper based bulk amorphous alloys,” M.S. - Master of Science, Middle East Technical University, 2013.