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Microstructure and High-temperature Oxidation Behavior of Ti3 AlC2/ W Composites.
- Source :
- Journal of the American Ceramic Society; Feb2013, Vol. 96 Issue 2, p584-591, 8p, 4 Black and White Photographs, 3 Charts, 5 Graphs
- Publication Year :
- 2013
-
Abstract
- Using spark plasma sintering, Ti<subscript>3</subscript> AlC<subscript>2</subscript>/ W composites were prepared at 1300°C. They contained 'core-shell' microstructures in which a Ti<subscript> x</subscript>W<subscript>1− x</subscript> 'shell' surrounded a W 'core', in a Ti<subscript>3</subscript> AlC<subscript>2</subscript> matrix. The composite hardness increased with W addition, and the hardening effect is likely achieved by the Ti<subscript> x</subscript> W<subscript>1− x</subscript> interfacial layer providing strong bonding between Ti<subscript>3</subscript> AlC<subscript>2</subscript> and W, and by the presence of hard W. Microstructural development during high-temperature oxidation of Ti<subscript>3</subscript> AlC<subscript>2</subscript>/ W composites involves α- Al<subscript>2</subscript> O<subscript>3</subscript> and rutile ( TiO<subscript>2</subscript>) formation ≥1000°C and Al<subscript>2</subscript> TiO<subscript>5</subscript> formation at ~1400°C while tungsten oxides appear to have volatilized above 800°C. Likely due to exaggerated, secondary grain growth of TiO<subscript>2</subscript>-doped alumina and the effect of W addition, fine (<1 μm) Al<subscript>2</subscript> O<subscript>3</subscript> grains formed dense, anisomorphic laths on Ti<subscript>3</subscript> AlC<subscript>2</subscript>/5 wt% W surfaces ≥1200°C and coarsened to large (>5 μm), dense, TiO<subscript>2</subscript>-doped Al<subscript>2</subscript> O<subscript>3</subscript> clusters on Ti<subscript>3</subscript> AlC<subscript>2</subscript>/10 wt% W surfaces ≥1400°C. W potentially affects the oxidation behavior of Ti<subscript>3</subscript> AlC<subscript>2</subscript>/ W composites beneficially by causing formation of Ti<subscript> x</subscript> W<subscript>1− x</subscript> thus altering the defect structure of Ti<subscript>3</subscript> AlC<subscript>2</subscript>, resulting in Al having a higher activity and by changing the scale morphology by forming dense Al<subscript>2</subscript> O<subscript>3</subscript> laths in a thinner oxide coating, and detrimentally through release of volatile tungsten oxides generating cavities in the oxide scale. For Ti<subscript>3</subscript> AlC<subscript>2</subscript>/5 wt% W oxidation, the former beneficial effects appear to dominate over the latter detrimental effect. [ABSTRACT FROM AUTHOR]
Details
- Language :
- English
- ISSN :
- 00027820
- Volume :
- 96
- Issue :
- 2
- Database :
- Complementary Index
- Journal :
- Journal of the American Ceramic Society
- Publication Type :
- Academic Journal
- Accession number :
- 85412135
- Full Text :
- https://doi.org/10.1111/jace.12095