1. Microstructure and High-temperature Oxidation Behavior of Ti3 AlC2/ W Composites.
- Author
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Cui, Bai, Zapata ‐ Solvas, Eugenio, Reece, Michael J., Wang, Chang ‐ an, Lee, William E., and Zhou, Y.
- Subjects
SINTERING ,MICROSTRUCTURE ,OXIDATION ,THIN films ,ALUMINUM oxide ,TUNGSTEN ,POWDER metallurgy - Abstract
Using spark plasma sintering, Ti
3 AlC2 / W composites were prepared at 1300°C. They contained 'core-shell' microstructures in which a Tix W1− x 'shell' surrounded a W 'core', in a Ti3 AlC2 matrix. The composite hardness increased with W addition, and the hardening effect is likely achieved by the Tix W1− x interfacial layer providing strong bonding between Ti3 AlC2 and W, and by the presence of hard W. Microstructural development during high-temperature oxidation of Ti3 AlC2 / W composites involves α- Al2 O3 and rutile ( TiO2 ) formation ≥1000°C and Al2 TiO5 formation at ~1400°C while tungsten oxides appear to have volatilized above 800°C. Likely due to exaggerated, secondary grain growth of TiO2 -doped alumina and the effect of W addition, fine (<1 μm) Al2 O3 grains formed dense, anisomorphic laths on Ti3 AlC2 /5 wt% W surfaces ≥1200°C and coarsened to large (>5 μm), dense, TiO2 -doped Al2 O3 clusters on Ti3 AlC2 /10 wt% W surfaces ≥1400°C. W potentially affects the oxidation behavior of Ti3 AlC2 / W composites beneficially by causing formation of Tix W1− x thus altering the defect structure of Ti3 AlC2 , resulting in Al having a higher activity and by changing the scale morphology by forming dense Al2 O3 laths in a thinner oxide coating, and detrimentally through release of volatile tungsten oxides generating cavities in the oxide scale. For Ti3 AlC2 /5 wt% W oxidation, the former beneficial effects appear to dominate over the latter detrimental effect. [ABSTRACT FROM AUTHOR]- Published
- 2013
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