Freely-migrating defects: Their production and interaction with cascade remnants

Conference · Wed May 01 04:00:00 EDT 1991

OSTI ID:5689530

Rehn, L E; Wiedersich, H

Many microstructural changes that occur during irradiation are driven primarily by freely-migrating defects, i.e. those defects which escape from nascent cascades to migrate over distances that are large relative to typical cascade dimensions. Several measurements during irradiation at elevated temperatures have shown that the survival rate of freely-migrating defects decreases much more strongly with increasing primary recoil energy than does the survival rate for defects generated at liquid helium temperatures. For typical fission or fusion recoil spectra, and for heavy-ion bombardment, the fraction of defects that migrate long-distances is apparently only {approximately}1% of the calculated dpa. This small surviving fraction of freely-migrating defects results at least partially from additional intracascade recombination at elevated temperatures. However, cascade remnants, e.g., vacancy and interstitial clusters, also contribute by enhancing intercascade defect annihilation. A recently developed rate-theory approach is used to discuss the relative importance of intra- and intercascade recombination to the survival rate of freely-migrating defects. Within the validity of certain simplifying assumptions, the additional sink density provided by defect clusters produced directly within individual cascades can explain the difference between a defect survival rate of about 30% for low dose, low temperature irradiations with heavy ions, and a survival rate of only {approximately}1% for freely-migrating defects at elevated temperatures. The status of our current understanding of freely-migrating defects, including remaining unanswered questions, is also discussed. 33 refs., 5 figs.

• Research Organization: Argonne National Lab., IL (USA)
• Sponsoring Organization: DOE; USDOE, Washington, DC (USA)
• DOE Contract Number: W-31109-ENG-38
• OSTI ID: 5689530
• Report Number(s): ANL/CP-72201; CONF-9105130--4; ON: DE91013618
• Country of Publication: United States
• Language: English

Related Subjects

36 MATERIALS SCIENCE
360106 -- Metals & Alloys-- Radiation Effects
38 RADIATION CHEMISTRY, RADIOCHEMISTRY, AND NUCLEAR CHEMISTRY
400701* -- Radiochemistry & Nuclear Chemistry-- Hot-Atom Chemistry
ANNIHILATION
BARYONS
BASIC INTERACTIONS
CRYSTAL STRUCTURE
DEFECTS
ELECTROMAGNETIC INTERACTIONS
ELEMENTARY PARTICLES
ELEMENTS
FERMIONS
HADRONS
INTERACTIONS
IRRADIATION
MEETINGS
METALS
MICROSTRUCTURE
NEUTRONS
NUCLEONS
PHYSICAL RADIATION EFFECTS
RADIATION EFFECTS
RECOILS
RECOMBINATION
SURVIVAL TIME
TEMPERATURE DEPENDENCE
THERMAL NEUTRONS