Evolution of defect cluster distributions during irradiation
Defects produced by irradiation are often strongly spatially correlated. Energetic primary recoil atoms produce cascades with vacant lattice sites predominantly in the central regions, and interstitial atoms at the periphery. A fraction of the defects produced form clusters during cascade events. Because of their spatial distribution more mobile interstitial atoms than vacancies are released into the matrix following the cascade events. Populations of vacancy and interstitial clusters evolve towards quasi-steady-state distributions. As long as vacancy clusters are thermally moderately stable, i.e., at temperatures below rapid self diffusion, an excess interstitial flux persists in the matrix; as a consequence, vacancy clusters formed in cascades shrink, and interstitial clusters grow. We examine the evolution of these cluster distributions, and their effects on sink strength and radiation-enhanced diffusion, as function of dose for irradiations at moderate temperatures. At temperatures at which thermal evaporation from vacancy clusters, can be neglected, the evolution of the cluster densities is characteristic of the primary recoil spectrum, but is independent of temperature or dose rate. The sink strength, radiation-enhanced diffusion, as well as other consequences of the evolving distributions such as the imbalance of the interstitial and vacancy fluxes in the matrix, approach slowly-changing quasi-steady-state values in a fraction of one displacement per atom, although certain details of the cluster distributions, e.g., the development of large interstitial loops, require several dpa's to approach steady state values. 22 refs., 6 figs.
- Research Organization:
- Argonne National Lab., IL (USA)
- Sponsoring Organization:
- USDOE; USDOE, Washington, DC (USA)
- DOE Contract Number:
- W-31109-ENG-38
- OSTI ID:
- 5663824
- Report Number(s):
- ANL/CP-72655; CONF-9105130-3; ON: DE91013405
- Resource Relation:
- Conference: International conference on physics of irradiation effects in metals, Siofok (Hungary), 20-24 May 1991
- Country of Publication:
- United States
- Language:
- English
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Implications of defect clusters formed in cascades on free defect generation and microstructural development
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Related Subjects
METALS
CRYSTAL DEFECTS
PHYSICAL RADIATION EFFECTS
ANNEALING
DIFFUSION
IRRADIATION
POINT DEFECTS
SPATIAL DISTRIBUTION
CRYSTAL STRUCTURE
DISTRIBUTION
ELEMENTS
HEAT TREATMENTS
RADIATION EFFECTS
360106* - Metals & Alloys- Radiation Effects
360102 - Metals & Alloys- Structure & Phase Studies