Nonequilibrium segregation and phase instability in alloy films during elevated-temperature irradiation in a high-voltage electron microscope
The effects of defect-production rate gradients, caused by the radial nonuniformity in the electron flux distribution, on solute segregation and phase stability in alloy films undergoing high-voltage electron-microscope (HVEM) irradiation at high temperatures are assessed. Two-dimensional (axially symmetric) compositional redistributions were calculated, taking into account both axial and transverse radial defect fluxes. It was found that when highly focused beams were employed radiation-induced segregation consisted of two stages: dominant axial segregation at the film surfaces at short irradiation times and competitive radial segregation at longer times. The average alloy composition within the irradiated region could differ greatly from that irradiated with a uniform beam, because of the additional atom transport from or to the region surrounding the irradiated zone under the influence of radial fluxes. As a result, damage-rate gradient effects must be taken into account when interpreting in-situ HVEM observations of segregation-induced phase instabilities. The theoretical predictions are compared with experimental observations of the temporal and spatial dependence of segregation-induced precipitation in thin films of Ni-Al, Ni-Ge and Ni-Si solid solutions.
- Research Organization:
- Argonne National Lab., IL (USA)
- DOE Contract Number:
- W-31-109-ENG-38
- OSTI ID:
- 6792249
- Report Number(s):
- CONF-840604-7; ON: DE84013423
- Resource Relation:
- Conference: 12. international symposium on effects of radiation on materials, Williamsburg, VA, USA, 18 Jun 1984; Other Information: Portions are illegible in microfiche products
- Country of Publication:
- United States
- Language:
- English
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Damage-rate gradient effects on radiation-induced segregation and phase stability in irradiated alloys
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Related Subjects
ALUMINIUM ALLOYS
PHYSICAL RADIATION EFFECTS
GERMANIUM ALLOYS
NICKEL BASE ALLOYS
SILICON ALLOYS
ELECTRON BEAMS
ELECTRON MICROSCOPY
HIGH TEMPERATURE
SEGREGATION
ALLOYS
BEAMS
LEPTON BEAMS
MICROSCOPY
NICKEL ALLOYS
PARTICLE BEAMS
RADIATION EFFECTS
360106* - Metals & Alloys- Radiation Effects