Processability and High Temperature Behavior of Emerging Aerospace Alloys
Abstract
In Part 1, a model for subgrain superplasticity has been developed. Aluminum alloys that contain low angle boundaries exhibit different superplastic behavior than alloys consisting of high angle boundaries. On a relative basis, the low angle boundaries increase the flow stress but impart a greater resistance to cavitation; the strain-rate sensitivity of this material is generally smaller and the change in the strain-rate sensitivity with strainrate shows a minimum instead of a maximum as observed in the large angle boundary materials. As a result, the subgrain material can be deformed to a large tensile strains at fast strain rates. A kinetic model for subgrain superplasticity that invokes a balance between the arrival and emission rates of disclosure at low angle boundaries is presented. It explains several features of subgrain superplasticity. It also explains why ultrafine dispersoids of intermetallics appear to stabilize the subgrain structure in aluminum. Early work on the correlation between flow stress and subgrain size in dynamic recrystallization of metals may also be consistent with the model. (JES)
Document Details
- Document Type
- Technical Report
- Publication Date
- Jun 01, 1990
- Accession Number
- ADA224285
Entities
People
- Ashish Ghosh
- C. G. Rhodes
- C. Ghandhi