Role of Vacancies and Solute Atoms on Grain Boundary Sliding
It is necessary for grain boundary dislocations to slide and climb during the grain boundary sliding process that dominates fine-grained superplastic deformation. The process of climb requires either an influx of vacancies to the grain boundary plane or a local generation of vacancies. Transmission electron microscopy (TEM) observations of grain boundaries in superplastically deformed Al-Mg-Mn alloys quenched under load from the deformation temperature have revealed the presence of nano-scale cavities resulting from a localized supersaturation of vacancies at the grain boundary. Compositional measurements along interfaces have also shown an effect of solute atoms on the local structure. This is shown to result from a coupling of vacancy and solute atom flows during deformation and quenching. Calculations of the localized vacancy concentration indicate that the supersaturation along the grain boundary can be as much as a factor of five. The effects of the local supersaturation and solute atom movement on deformation rates and cavity nucleation and growth will be discussed.
- Research Organization:
- Pacific Northwest National Lab. (PNNL), Richland, WA (United States)
- Sponsoring Organization:
- USDOE
- DOE Contract Number:
- AC05-76RL01830
- OSTI ID:
- 15007437
- Report Number(s):
- PNNL-SA-32478; KC0201020
- Resource Relation:
- Conference: MATERIALS RESEARCH SOCIETY SYMPOSIUM PROCEEDINGS, 1999 Nov : Boston, MA, 601:169-174
- Country of Publication:
- United States
- Language:
- English
Similar Records
Evidence for excess vacancies at sliding grain boundaries during superplastic deformation
Microstructural evolution during superplastic deformation in large-grained iron aluminides