Precipitation in solution-treated Al-4wt%Cu under cyclic strain
- Los Alamos National Laboratory
- U PENN
Solution-treated Al-4wt%Cu was strain-cycled at ambient temperature and above and the precipitation behavior investigated by TEM. In the temperature range 100 C to 200 C precipitation of {Theta}'' appears to have been suppressed and precipitation of {Theta}' promoted via cyclic strain. Anomalously rapid growth of precipitates appears to have been facilitated by a vacancy supersaturation generated by dislocation motion, with a diminishing effect observed at higher temperatures due to the faster recovery of non-equilibrium vacancy concentrations. {Theta}' precipitates generated under cyclic strain are considerably smaller and more finely dispersed than those typically produced via quench-aging due to their heterogeneous nucleation on dislocations, and possess a low aspect ratio and rounded edges of the broad faces due to the introduction of ledges into the growing precipitates by dislocation cutting. Frequency effects indicate that dislocation motion, rather than the extremely small precipitate size, is responsible for the observed reduction in aspect ratio. Accelerated formation of grain boundary precipitates appears partially responsible for rapid intergranular fatigue failure following cycling at elevated temperatures, producing fatigue striations and ductile dimples coexistent on the fracture surface.
- Research Organization:
- Los Alamos National Laboratory (LANL), Los Alamos, NM (United States)
- Sponsoring Organization:
- USDOE
- DOE Contract Number:
- AC52-06NA25396
- OSTI ID:
- 1033577
- Report Number(s):
- LA-UR-10-06249; LA-UR-10-6249; TRN: US201203%%10
- Resource Relation:
- Journal Volume: 172-174; Conference: PTM 2010 ; June 6, 2010 ; Avignon, France
- Country of Publication:
- United States
- Language:
- English
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