DEFECT PRODUCTION, INTERNAL FRICTION AND YOUNG'S MODULUS IN IRRADIATED TUNGSTEN
The effect of 10 to 14 Mev deuteron irradiation on tungsten was studied experimentally. Two aspects of this problem were examined. The first was a study of the incident deuteron energy dependence of defect production; the second was a study of the effect of radioinduced defects on mechanical properties. The change in the electrical resistance of the metal with bombardment was used to study the rate of defect production. The rate of defect production in tungsten is shown experimentally to depend on the energy of the incident deuteron almost as 1/E. This result was compared with a theory for defect production in metals by charged particle irradiation. The small deviation of the experimental results from a 1/E dependence was in a direction opposite to the deviation from a 1/E dependence predicted from a hard sphere model for secondary defect production. The results of measurements of internal friction and Young's modulus as a function of temperature and incident 14 Mev deuteron flux are presented. Evidence is given for the association of at least a part of the internal friction in tungsten with dislocations. A Bordoni-dislocation relaxation peak was observed; a fit of the Bordoni peak data to a single activation energy relaxation model gave a value of 0.2l ev for the activation energy, and a value of 1.5 x 10/ sup 10/ cps for the attempt frequency. The Bordoni peak is shown to be generally reduced in height by irradiation at 300 deg K; after irradiation, several smaller, sharper peaks appear. Data are given showing a decrease in internal friction and an increase in Young's modulus with irradiation at 300 deg K. This effect saturates at a flux of 1 x 10/sup 16/ deuterons/cm/sup 2/. The decrease in internal friction and the increase in Young's modulus with irradiation are attributed to the pinning of dislocations by radiation induced interstitials. At 300 deg K Young's modulus decreased linearly with incident flux in the range 1 x 10/sup 16/ to 1 x 10/sup 17/ deuterons/cm/sup 2/. This linear decrease was attributed to the bulk effect of radioinduced vacancies frozen into the lattice at 300 deg K. A value of 0.44% change in Young's modulus per atomic per cent of vacancies was deduced from these data; this value was compared with Dienes' prediction of 1.0%. The effect of irradiation at 79 deg K on internal friction in tungsten was studied. A series of very high, very sharp peaks in the internal friction vs. temperature curve are reported for the anneal of the sample to 300 deg K. These peaks were not present during subsequent measurements of internal friction vs. temperature. It is suggested that these internal friction annealing peaks might arise from thermal activated motion of interstitials.
- Research Organization:
- Univ. of Pittsburgh
- NSA Number:
- NSA-16-022657
- OSTI ID:
- 4836146
- Journal Information:
- Dissertation Abstr., Vol. Vol: 22; Other Information: Orig. Receipt Date: 31-DEC-62
- Country of Publication:
- Country unknown/Code not available
- Language:
- English
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Related Subjects
ACTIVATION ENERGY
ANNEALING
BORDONI PEAKS
CHARGED PARTICLES
DEFECTS
DEUTERON BEAMS
DIFFUSION
DISLOCATIONS
ELASTICITY
ELECTRIC CONDUCTIVITY
ENERGY
ENERGY RANGE
EXCITATION
FREQUENCY
FRICTION
INTERACTIONS
INTERSTITIALS
IRRADIATION
LATTICES
MEASURED VALUES
MECHANICAL PROPERTIES
QUANTITATIVE ANALYSIS
QUANTITY RATIO
RADIATION DOSES
RADIATION EFFECTS
RELAXATION
TEMPERATURE
TUNGSTEN
VACANCIES
YOUNG MODULUS