Direct observation of the point-defect structure of depleted-zones in ion-irradiated metals
The point-defect structure of individual depleted zones has been studied systematically. Four-pass zone-refined tungsten field-ion microscope (FIM) specimens were irradiated in-situ at 10 K with 30 keV Cr/sup +/, Mo/sup +/, or W/sup +/ ions to a total dose of (2 to 10) x 10/sup 12/ ion cm/sup -2/ and examined by the pulse field-evaporation technique at 10 K. The experimental conditions were such that each depleted zone was created by a single incident-ion. The number of vacant lattice sites within a depleted zone was compared with a modified Kinchin--Pease model. The radial distribution function was determined for each depleted zone; it was found that the vacant lattice sites within the volume of each depleted zone tended to exist in a highly clustered state. It was found that the diameter D of each depleted zone was described by the equation D approximately equal to (y/sup 2/)/sup /sup 1///sub 2// where (y/sup 2/)/sup /sup 1///sub 2// is the second moment of the theoretical distribution curve, of the fraction of incident ion energy deposited in atom motion, transverse to the direction of the incident ion-beam. The spatial distribution of self-interstitial atoms (SIAs) in a specimen irradiated with 30 keV Cr/sup +/ ions and in a specimen irradiated with 18 keV Au/sup +/ ions, at 10 K, was determined. A low bound to the average range of replacement collision sequences (RCSs) was found to be 175 +- 85 A. A detailed FIM study was also made of the vacancy structure of a (220) platelet created by a single 30 keV W/sup +/ ion in a platinum-4.0 at. % gold alloy; the specimen was irradiated at 40 K and then isochronally warmed to 100 K. The (220) platelet was found to consist of 31 vacant lattice sites, lying in four (220) planes, and clustered in a disc-shaped region which is approximately 20 A in diameter. It was suggested that prismatic dislocation loops lying on (220) type planes in ion or fast neutron irradiated platinum can form as a result of the direct collapse of (220) type vacancy platelets.
- Research Organization:
- Cornell Univ., Ithaca, N.Y. (USA). Dept. of Materials Science and Engineering
- DOE Contract Number:
- EY-76-S-02-3158
- OSTI ID:
- 6796884
- Report Number(s):
- COO-3158-62; TRN: 78-013564
- Resource Relation:
- Other Information: Thesis. Portions of document are illegible
- Country of Publication:
- United States
- Language:
- English
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GOLD ALLOYS
PHYSICAL RADIATION EFFECTS
PLATINUM BASE ALLOYS
TUNGSTEN
CHROMIUM IONS
KEV RANGE 10-100
MOLYBDENUM IONS
POINT DEFECTS
TUNGSTEN IONS
ALLOYS
ATOMIC IONS
CHARGED PARTICLES
CRYSTAL DEFECTS
CRYSTAL STRUCTURE
ELEMENTS
ENERGY RANGE
IONS
KEV RANGE
METALS
PLATINUM ALLOYS
PLATINUM METAL ALLOYS
RADIATION EFFECTS
REFRACTORY METALS
TRANSITION ELEMENTS
360106* - Metals & Alloys- Radiation Effects