Effects of electron irradiation on precipitation in Ni--Al alloys
- SCM Corp., Cleveland, OH
Binary Ni--Al alloys have been irradiated in situ by high voltage electron microscopy (650 kV) in order to investigate the effects on precipitation. Nucleation and growth of dislocation loops are observed during irradiation in the temperature range 20 to 650/sup 0/C. In solution-treated specimens, large faulted loops form during irradiation at 500/sup 0/C. Contrast analysis shows that loops are Frank-type with 1/3 (111) Burgers vectors and interstitial in character. At 650/sup 0/C and above, loop formation and growth are not observed once ..gamma..' precipitates have formed. In preaged specimens, much smaller loops form during irradiations at below 500/sup 0/C. At 500/sup 0/C and above, no loops are observed in specimens containing large volume fractions of precipitates. The spatial distribution of loops appears rather uniform regardless of the presence of ..gamma..' precipitates except when large incoherent precipitates exist. The growth of ..gamma..' precipitates is enhanced by irradiation in the temperature range 300 to 750/sup 0/C. Precipitate coarsening under irradiation follows radiation-enhanced diffusion kinetics. Quantitative analysis demonstrates that the radiation-enhanced diffusion coefficient responsible for coarsening of ..gamma..' is independent of the temperature between 300 and 650/sup 0/C. This result is in agreement with theoretical predictions for the case in which irradiation-produced point defects are lost by their annealing at fixed sinks.
- OSTI ID:
- 6348640
- Journal Information:
- Metall. Trans., A; (United States), Journal Name: Metall. Trans., A; (United States) Vol. 9:12; ISSN MTTAB
- Country of Publication:
- United States
- Language:
- English
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Related Subjects
360102 -- Metals & Alloys-- Structure & Phase Studies
360106* -- Metals & Alloys-- Radiation Effects
ALLOYS
ALUMINIUM ALLOYS
ARRHENIUS EQUATION
CRYSTAL DEFECTS
CRYSTAL STRUCTURE
DIFFUSION
DISLOCATIONS
ELECTRON MICROSCOPY
ELECTRONS
ELEMENTARY PARTICLES
FERMIONS
LEPTONS
LINE DEFECTS
MICROSCOPY
MICROSTRUCTURE
NICKEL ALLOYS
NICKEL BASE ALLOYS
NUCLEATION
PHYSICAL RADIATION EFFECTS
POINT DEFECTS
PRECIPITATION
RADIATION EFFECTS
SEGREGATION
SEPARATION PROCESSES
STABILITY
TEMPERATURE DEPENDENCE
TRANSMISSION ELECTRON MICROSCOPY