Investigation of radiation damage in metals in a high-voltage electron microscope (in German)
The agglomeration of Frenkel defects that occur in nickel and copper single crystals as a result of electron irradiation is studied. Under irradiation at large electron doses at 8 deg K, the formation of new types of contrasts was observed; these can be attributed to an unexplained form of defect agglomerates. It can be concluded that an agglomeration of defects is possible at low temperatures at which a far-reacting diffusion is not possible. Samples irradiated at 8 deg K show, under controlled heating in the microscope, characteristic changes of visible radiation damages at temperatures which can be correlated with the known recovery stages as shown by the electrical resistance. In the temperature range 300 to 810 deg K the formation of interstitial atom dislocation rings was observed. From 480 deg K upwards. vacancy agglomerates are also formed. These agglomerates are dislocation rings in high purity samples and, in samples containing gas impurities, are either stacking fault tetrahedrons or voids. The time and temperature dependence of the growth rate of the interstitial atom dislocation rings was quantitatively investigated. The defect concentrations which occur in thin metal sheets during irradiation at high temperatures were calculated. From the experimental observations. conclusions can be drawn about special nucleus formation conditions in thin sheets. The conditions for the formation of interstitial atom and vacancy agglomerates could be directly derived from the experimental results. These concepts are used in a model in order to calculate the temperature dependence of the growth rate of interstitial atom dislocation rings. A cryogenic object holder developed for the Hitachi microscope is described. The cooling system permits irradiation and simultaneous investigation in the microscope at temperatures between 8 and 300 deg K without affecting the optical resolving quality of the instrument. (GE)
- Research Organization:
- Originating Research Org. not identified
- NSA Number:
- NSA-29-013231
- OSTI ID:
- 4363873
- Country of Publication:
- Germany
- Language:
- German
Similar Records
The stability of irradiation-induced defects in NiAl
Diffuse x-ray radiation scattering on copper after irradiation with neutrons at low temperatures
Related Subjects
*NICKEL-- PHYSICAL RADIATION EFFECTS
DIFFUSION
DISLOCATIONS
ELECTRON BEAMS
ELECTRON MICROSCOPY
ELECTRONS
FRENKEL DEFECTS
HIGH TEMPERATURE
INTERSTITIALS
LOW TEMPERATURE
MEDIUM TEMPERATURE
MONOCRYSTALS
N50240* --Metals
Ceramics
& Other Materials--Metals & Alloys--Radiation Effects
TEMPERATURE DEPENDENCE
ULTRALOW TEMPERATURE
VERY LOW TEMPERATURE