DIFFUSION INVESTIGATIONS IN THE NIOBIUM-TUNGSTEN SYSTEM FOR POLYCRYSTAL, SINGLE-CRYSTAL, AND SPRAY COUPLES. II. SINGLE-CRYSTAL COUPLES (in German)
The diffusion in couples of single crystals of tungsten and niobium was studied by means of the micro-hardness method. A number of annealed alloy buttons were hardness checked for a hardness versus concentration plot, which made it possible to convert the hardness values of the diffusion samples into concentration values. The single crystals used were combined in two columns with the sequence W(100) -Nb(100) -W(131) -Nb(110) -W(100). One column was held in a tungsten tube furnace at 2100 deg C for times up to 390 hours with intervening inspections after 100 and 200 hours, respectively. The other column was held at 1900 deg C for times up to 500 hours with the intervening inspections after 112 and 212 hours, respectively. The diffusion coefficient for various concentration steps was calculated according to the Matano-Method. The coefficients for couples of single crystals proved to depend strongly on the concentration, i.e., in the same manner as they did for couples of polycrystalline tungsten and niobium. The diffusion coefficient for the single crystal couples held at 2100 deg C decreased from 1.4 to 1.9 x 10/sup -5/ cm/sup 2//sec for 10 at.% W to 1.5to 2.5 x 10/sup -7/ cm/sup 2//sec for 90 at.% W. The corresponding values at the annealing temperature of 1900 deg C were 1 to 2 x 10/sup -7/cm/sec for the concentration step l0 at.% W and 3 to 5 x 10/sup -9/ cm/sec for 90 at.% W. An influence of the orientation on the diffusion could not be observed because the strong concentration dependence overwhelmed fine deviations. (auth)
- Research Organization:
- Max-Planck-Institut fur Metallforschung, Stuttgart
- NSA Number:
- NSA-18-008857
- OSTI ID:
- 4106099
- Journal Information:
- Z. Metallk., Vol. Vol: 54; Other Information: Orig. Receipt Date: 31-DEC-64
- Country of Publication:
- Country unknown/Code not available
- Language:
- German
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