Chemistry on a subnanometer scale of radiation-induced precipitation and segregation in fast-neutron irradiated tungsten-rhenium alloys
W-10 at.% Re and W-25 at.% Re alloys were investigated, employing the atom-probe field-ion-microscope technique. The W-10 at.% Re is subsaturated with respect to the solvus line of the primary solid solution (..beta.. phase), while the W-25 at.% Re alloy is supersaturated with respect to the same solvus line. Results on EBR-2-irradiated specimens show a significant alteration of the microstructure. In the case of W-10 at.% Re, precipitates with the composition approx. WRe and a disc-shaped morphology were detected at a number density of approx. 10/sup 16/ cm/sup -3/, and a mean diameter of approx. 57 A. For W-25 at.% Re, precipitates with the composition approx. WRe/sub 3/ were detected; the precipitate's number density is approx. 10/sup 17/ cm/sup -3/ with a mean diameter of 40 A. None of the approx. WRe precipitates or the approx. WRe/sub 3/ coherent precipitates were associated with either line or planar defects or with any impurity atoms, indicating a true homogeneous radiation-induced precipitation. The semicoherent WRe/sub 3/ precipitates were associated with /sup 4/He atoms. In W-25 at.% Re, a two-dimensional WRe/sub 3/ phase has been observed at a grain boundary. An argument is presented for the nucleation of WRe or WRe/sub 3/ precipitates in the viciniity of the displacement cascades. It is suggested that in both cases the first step in the nucleation of a precipitate is due to the formation of tightly-bound mobile mixed dumbbells which react to form an immobile di-rhenium cluster. Possible sequences of point-defect reactions which can lead to either WRe or WRe/sub 3/ cluster are detailed. The further growth of a cluster (WRe or WRe/sub 3/) into a precipitate is most likely driven by the irreversible vacancy: self-interstitial atom annihilation reaction. Point-defect mechanisms for all the other observations are also discussed.
- Research Organization:
- Cornell Univ., Ithaca, NY (USA)
- DOE Contract Number:
- AC02-76ER03158
- OSTI ID:
- 5256817
- Report Number(s):
- DOE/ER/03158-117; CONF-840271-1; ON: DE84009142
- Resource Relation:
- Conference: 2. Israel materials engineering conference, Beer-Sheva, Israel, 22 Feb 1984
- Country of Publication:
- United States
- Language:
- English
Similar Records
Atomic resolution study of radiation-induced precipitation and solute segregation effects in a neutron-irradiated W-25 at. % Re alloy
Atomic-resolution study of homogeneous radiation-induced precipitation in a neutron-irradiated W-10 at. % Re alloy. MSC report No. 5014
Related Subjects
RHENIUM ALLOYS
PHYSICAL RADIATION EFFECTS
TUNGSTEN BASE ALLOYS
FAST NEUTRONS
ION MICROSCOPY
NEUTRON BEAMS
SEGREGATION
ALLOYS
BARYONS
BEAMS
ELEMENTARY PARTICLES
FERMIONS
HADRONS
MICROSCOPY
NEUTRONS
NUCLEON BEAMS
NUCLEONS
PARTICLE BEAMS
RADIATION EFFECTS
TUNGSTEN ALLOYS
360106* - Metals & Alloys- Radiation Effects