Study on the early surface films formed on Mg-Y molten alloy in different atmospheres

Mirak, A. R., Davidson, C. J. and Taylor, J. A. (2015) Study on the early surface films formed on Mg-Y molten alloy in different atmospheres. Journal of Magnesium and Alloys, 3 3: 173-179. doi:10.1016/j.jma.2015.06.003


Author Mirak, A. R.
Davidson, C. J.
Taylor, J. A.
Title Study on the early surface films formed on Mg-Y molten alloy in different atmospheres
Journal name Journal of Magnesium and Alloys   Check publisher's open access policy
ISSN 2213-9567
Publication date 2015-09-01
Sub-type Article (original research)
DOI 10.1016/j.jma.2015.06.003
Open Access Status DOI
Volume 3
Issue 3
Start page 173
End page 179
Total pages 7
Place of publication Amsterdam, The Netherlands
Publisher Elsevier BV
Language eng
Formatted abstract
In the present study, the non-isothermal early stages of surface oxidation of liquid Mg-1%Y alloy during casting were studied under UPH argon, dry air, and air mixed with protective fluorine-bearing gases. The chemistry and morphology of the surface films were characterized by SEM and EDX analyses. The results indicate a layer of smooth and tightly coherent oxidation film composed of MgO and Y2O3 formed on the molten Mg-Y alloy surface with 40–60 nm thickness under dry air. A dendritic/cellular microstructure is clearly visible with Y-rich second phases gathered in surface of the melt and precipitated along the grain/cell boundaries under all gas conditions. Under fluorine-bearing gas mixtures, the surface film was a mixed oxide and fluoride and more even; a flat and folded morphology can be seen under SF6 with oxide as dominated phase and under 1, 1, 1, 2-tetra-fluoroethane, a smooth and compact surface film uniformly covering the inner surface of the bubble with equal oxide and fluoride thickness, which results in a film without any major defects. MgF2 phase appears to be the key characteristic of a good protective film.
Keyword Early surface film
EDX
Fluoridation
Mg-Y alloy
Oxidation
SEM
Q-Index Code C1
Q-Index Status Provisional Code
Institutional Status UQ

Document type: Journal Article
Sub-type: Article (original research)
Collection: School of Mechanical & Mining Engineering Publications
 
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Created: Mon, 01 Aug 2016, 21:01:16 EST by Mary-Anne Marrington on behalf of School of Mechanical and Mining Engineering