Direct observation of the point-defect structure of depleted-zones in ion-irradiated metals

Technical Report · Sun Jan 01 04:00:00 EST 1978

DOI:https://doi.org/10.2172/6796884· OSTI ID:6796884

Wei, C.

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
• Country of Publication: United States
• Language: English

Related Subjects

36 MATERIALS SCIENCE
360106* -- Metals & Alloys-- Radiation Effects
ALLOYS
ATOMIC IONS
CHARGED PARTICLES
CHROMIUM IONS
CRYSTAL DEFECTS
CRYSTAL STRUCTURE
ELEMENTS
ENERGY RANGE
GOLD ALLOYS
IONS
KEV RANGE
KEV RANGE 10-100
METALS
MOLYBDENUM IONS
PHYSICAL RADIATION EFFECTS
PLATINUM ALLOYS
PLATINUM BASE ALLOYS
PLATINUM METAL ALLOYS
POINT DEFECTS
RADIATION EFFECTS
REFRACTORY METALS
TRANSITION ELEMENTS
TUNGSTEN
TUNGSTEN IONS