Date of Award

Spring 2014

Degree Type

Thesis

Degree Name

Master of Science (MS)

Department

Materials Engineering

First Advisor

Lia Stanciu

Committee Member 1

David Johnson

Committee Member 2

John Howarter

Committee Member 3

Elliott Slamovich

Abstract

Bulk Metallic Glass has become famous for its exceptional mechanical and corrosion properties. Especially, Zirconium has been the prominent constituent in Bulk Metallic Glass due to its superior glass forming ability, the ability to form amorphous phase with low cooling rate, thereby giving advantages in structural applications.

In this study, Zirconium powder was alloyed with Aluminum, Nickel and Copper powder at an atomic ratio of 65:10:10:15, respectively. Using the ball milling process to mix the powders, Zr65 Al10 Ni 10 Cu15 amorphous structure was manufactured by laser direct deposition.

Laser power and laser scanning speed were optimized to increase the fraction of amorphous phase. X-ray Diffraction confirmed the existence of both amorphous and crystalline phase by having a wide halo peak and sharp intense peak in the spectrum. Differential Scanning Calorimetry proved the presence of amorphous phase and glass transition was observed to be around 655 K. Scanning electron microscopy showed the microstructure of the deposited sample to have repetitive amorphous and crystalline phase as XRD examined. Crystalline phase resulted from the laser reheating and remelting process due to subsequent laser scan. Laser direct deposited amorphous/crystalline composite showed Vickers Hardness of 670 Hv and exhibited improved corrosion resistance in comparison to fully-crystallized sample. The compression test showed that, due to the existence of crystalline phase, fracture strain of Zr 65 Al10 Ni10 Cu 15 amorphous composites was enhanced from less than 2% to as high as 5.7%, compared with fully amorphous metallic glass.

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