UA cloudflare authentication

 

An analysis of the grain refinement of magnesium by zirconium

Simple item page
dc.contributorThompson, Gregory B.
dc.contributorChopra, Nitin
dc.contributorAndrews, J. Barry
dc.contributorBatson, Robert G.
dc.contributor.advisorViswanathan, S.
dc.contributor.authorSaha, Partha
dc.contributor.otherUniversity of Alabama Tuscaloosa
dc.date.accessioned2017-03-01T14:36:54Z
dc.date.available2017-03-01T14:36:54Z
dc.date.issued2010
dc.descriptionElectronic Thesis or Dissertationen_US
dc.description.abstractA Design of Experiments (DOE) approach was used to conduct a systematic study of the grain refinement of magnesium by zirconium; variables included the amount of zirconium, the pouring temperature, and the settling time prior to casting. Samples were poured into a special "hockey puck" mold designed to reproduce the conditions in permanent mold casting. Optical and scanning electron microscopy (SEM) was utilized to measure the grain size in the final microstructure. Sample dissolution followed by SEM was used to characterize zirconium particle size and morphology both in the master alloy and grain refined samples, while an AccuSizer 770 Photozone/Light Obscuration instrument was used to measure total particle size distributions in the master alloy and grain refined samples. Transmission Electron Microscopy (TEM) was used to identify particles that likely act as suitable heterogeneous nucleation sites for grain refinement. The TEM results show that a range of particle sizes are likely substrates and that only zirconium particles which are faceted are likely nucleation sites. It is apparent that only 1 to 3% of the total particles serve as nucleation sites, but a comparison of the grain density vs. faceted particle density shows close agreement. Equal Channel Angular Extrusion (ECAE) processing of the magnesium-15wt% zirconium master alloy to increase the number of faceted particles resulted in improved grain refinement efficacy. This work suggests that there is a tremendous potential to engineer a more efficient grain refiner.en_US
dc.format.extent98 p.
dc.format.mediumelectronic
dc.format.mimetypeapplication/pdf
dc.identifier.otheru0015_0000001_0000461
dc.identifier.otherSAHA_alatus_0004D_10503
dc.identifier.urihttps://ir.ua.edu/handle/123456789/966
dc.languageEnglish
dc.language.isoen_US
dc.publisherUniversity of Alabama Libraries
dc.relation.hasversionborn digital
dc.relation.ispartofThe University of Alabama Electronic Theses and Dissertations
dc.relation.ispartofThe University of Alabama Libraries Digital Collections
dc.rightsAll rights reserved by the author unless otherwise indicated.en_US
dc.subjectEngineering, Metallurgy
dc.titleAn analysis of the grain refinement of magnesium by zirconiumen_US
dc.typethesis
dc.typetext
etdms.degree.departmentUniversity of Alabama. Department of Metallurgical and Materials Engineering
etdms.degree.disciplineMetallurgical/Materials Engineering
etdms.degree.grantorThe University of Alabama
etdms.degree.leveldoctoral
etdms.degree.namePh.D.

Files

Original bundle
Now showing 1 - 1 of 1
Thumbnail Image
Name:
file_1.pdf
Size:
4.05 MB
Format:
Adobe Portable Document Format
Download

Collections

Theses and Dissertations
Theses and Dissertations - Department of Metallurgical and Materials Engineering