Oxidation of Tantalum in the Temperature Range 500 deg - 700 C.
Abstract
The oxidation behaviour of Ta was studied in the temperature range 500 to 700 C and at O pressures ranging from 760 to 0.1 torr. The work comprises oxidation rate measurements and structural investigations of oxidized specimens by means of X-ray diffraction, electron diffraction, electron microscopy and metallographic techniques. During initial stages oxidation of Ta constitutes oxygen dissolution in the metal and the formation of one or two suboxides, ermed Ta4O and TaOz, where TaOz probably is the end structure of an intermediate precipitation phase resulting from an ordering of dissolved oxygen along dislocations and low-angle grain boundaries. During later stages a transition to a breakaway oxidation which eventually follows a linear rate is observed. The latter oxidation stage is accompanied by heavy Ta2O5-formation. The linear oxidation is interpreted in terms of an oxygen chemisorption equilibrium followed by a rate-determining reaction governed by nucleation and growth of Ta2O5-nuclei. (Author)
Document Details
- Document Type
- Technical Report
- Publication Date
- Apr 01, 1961
- Accession Number
- AD0267074