The Creep and Solidification Behavior of Al-Al3Ni Eutectic Whisker Composites.
Abstract
The strength of the Al-Al3Ni eutectic was shown to be increased by increasing the solidification rate, which has the effect of decreasing the whisker size and interwhisker spacing. In transverse compressive yield strength measurements at room temperature, the dependence of the yield strength on the solidification rate was indicative of the presence of a dispersion strengthening effect of the whiskers on the matrix. The longitudinal compressive yield strengths also increased with decreasing interwhisker spacing. Creep resistance was greatly enhanced with increasing solidification rate, with lower steady state creep rates and longer times to rupture being found in high solidification rate ingots, even when tested at higher temperatures. Scanning electron microscopy was used to reveal whisker morphology in three dimensions in regions where the matrix was etched back from the whiskers. Whisker branching was observed in the solidification direction. The observed branching fits with predictions and explains the changes in whisker concentration observed in the eutectic exhibiting the dual-orientation microstructure. The abrupt changes in whisker direction from axially oriented to misoriented in dually-oriented eutectic and back again was clearly observed. (Author)
Document Details
- Document Type
- Technical Report
- Publication Date
- Jun 30, 1971
- Accession Number
- AD0727615
Entities
People
- Earl R. Thompson
- Edward M. Breinan