Implications of defect clusters formed in cascades on free defect generation and microstructural development
A large fraction of the defects produced by irradiation with energetic neutrons or heavy ions originates in cascades. Not only increased recombination of vacancy and interstitial defects but also significant clustering of like defects occur. Both processes reduce the number of point defects available for long range migration. Consequences of defect clustering in cascades will be discussed in a semi-quantitative form with the aid of calculations using a very simplified model: Quasi-steady-state distributions of immobile vacancy and/or interstitial clusters develop which, in turn, can become significant sinks for mobile defects, and, therefore reduce their lifetime. Although cluster sinks will cause segregation and, potentially, precipitation of second phases due to local changes of composition, the finite lifetime of clusters will not lead to lasting, local compositional changes. A transition from highly dense interstitial and vacancy cluster distributions to the void swelling regime occurs when the thermal evaporation of vacancies from small vacancy clusters becomes significant at higher temperatures. Unequal clustering of vacancies and interstitials leads to an imbalance of their fluxes of in the matrix and, hence, to unequal contributions to atom transport by interstitials and by vacancies even in the quasi-steady state approximation.
- Research Organization:
- Argonne National Lab., IL (United States)
- Sponsoring Organization:
- USDOE, Washington, DC (United States)
- DOE Contract Number:
- W-31109-ENG-38
- OSTI ID:
- 10118109
- Report Number(s):
- ANL/MSD/CP-78287; CONF-920970-6; ON: DE93005551
- Resource Relation:
- Conference: 3. conference on evolution of microstructure in metals during irradiation,Chalk River (Canada),29 Sep - 2 Oct 1992; Other Information: PBD: Dec 1992
- Country of Publication:
- United States
- Language:
- English
Similar Records
Evolution of defect cluster distributions during irradiation
The effect of defect clusters formed in cascades on the sink strength in irradiated materials