DIFFUSION INVESTIGATION IN THE TUNGSTEN-NIOBIUM SYSTEM ON POLYCRYSTALLINE, SINGLE-CRYSTAL, AND SPRAYED COUPLES. I. POLYCRYSTALLINE COUPLES (in German)
The diffusion in couples of polycrystalline tungsten and niobium was studied by means of the microhardness method. A number of alloy butions were arc melted, annealed, and hardness checked in order to get a hardness vs. concentration plot from which the hardness values of the diffusion samples could be converted to concentration values. The hardness graph of the completely miscible W-Nb system had a maximum at approximately 40 at.% Nb. The diffusion couples were held at 2100 and 1900 deg C for times up to 500 hours. The diifusion coefficients were calculated according to the Matano method. They proved to depend very much on the concentration and increased from the W side of the system to the Nb side by two orders of magnitude. D = 1.6 x 10/sup -7/ cm/ sup 2//sec for 10 at.% Nb--90 at.% W, D = 1.4 x 10/sup -6/ cm/sup 2//sec for 90 at.% Nb-10 at.% W at 2100 deg C, and D = 5 x 10/sup -9/ cm/sup 2//sec for 10 at.% Nb-90 at.% W, D = 1.16 X 10/sup -7/ cm/sup 2//sec for 90 at.% Nb-10 at.% W at 1900 deg C, respectively. The diffusion coefficient proved to depend strongly on the temperature. From a (log D-1/T) plot the activation energy was calculated. The values were high, compared with the values from other diffusion studies. (auth)
- Research Organization:
- Max-Planck-Institut fur Metallforschung, Stuttgart
- NSA Number:
- NSA-17-037553
- OSTI ID:
- 4630523
- Journal Information:
- Z. Metallk., Vol. Vol: 54; Other Information: Orig. Receipt Date: 31-DEC-63
- Country of Publication:
- Country unknown/Code not available
- Language:
- German
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