Interdiffusion in the Ta-W system
Interdiffusion in the Ta-W system, a continuous body-centered-cubic solid solution, has been investigated in the temperature range 1300--2100 /sup 0/C with single-phase diffusion couples prepared by chemical vapor deposition. Fine inclusions, presumably oxides or carbides, decorated the couple interfaces and served as Kirkendall markers. The diffusion annealing times ranged from 16 h to 220 days. The resulting concentration profiles were measured with the electron microprobe and analytical electron microscope. The chemical diffusion coefficient was determined by the classical Boltzmann--Matano technique. The intrinsic diffusivities were determined by the technique of Darken. In the composition range 20--80 at. % W, the activation energy Q for chemical diffusion was constant at 130.5 +- 1.5 kcal/mole. The activation energies for the intrinsic diffusion coefficients at the composition of the Kirkendall marker plane, approximately 70 at. % W, were Q(Ta) = 132.3 +- 0.5 kcal/mole and Q(W) = 122.0 +- 0.5 kcal/mole.
- Research Organization:
- Sandia National Laboratories, Albuquerque, New Mexico 87185
- DOE Contract Number:
- AC04-76DP00789
- OSTI ID:
- 5330336
- Journal Information:
- J. Appl. Phys.; (United States), Journal Name: J. Appl. Phys.; (United States) Vol. 58:9; ISSN JAPIA
- Country of Publication:
- United States
- Language:
- English
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Related Subjects
360104* -- Metals & Alloys-- Physical Properties
ACTIVATION ENERGY
ALLOYS
ANNEALING
CHEMICAL ANALYSIS
CHEMICAL COATING
CHEMICAL VAPOR DEPOSITION
DEPOSITION
DIFFUSION
ELECTRON MICROPROBE ANALYSIS
ELECTRON MICROSCOPY
ENERGY
HEAT TREATMENTS
MICROANALYSIS
MICROSCOPY
SURFACE COATING
TANTALUM ALLOYS
TUNGSTEN ALLOYS
VERY HIGH TEMPERATURE