Conference proceeding
Structure and Segregation of Stir-Cast Aluminium Alloys
Solidification Technology in the Foundry and Cast House; Coventry; England; 15-17 Sept. 1980, pp.119-125
15 Sep 1980
Abstract
Microstructural and microanalytical studies, including the use of electron channelling patterns, have shown that grain boundaries are very frequently found within and between solid particles in stir-cast Al and its alloys. The grain boundaries show an unusual range of misorientations: mainly low angle, with some twin boundaries and a small but significant proportion of special high angle (coincident site) boundaries. The origin of this distribution of misorientations arises from the fact that only boundaries whose energy ( sigma sub b ) is less than twice the energy ( sigma sub sl ) of the solid/liquid interface can survive in a liquid matrix. Solute segregation was found at somewhat less than 50% of the boundaries studied. These observations provide strong support for the proposed mechanism of the development of the stir-cast microstructure and its thixotropic properties. The mechanism is that of plastic deformation followed by recrystallization, this providing grain boundaries which will `melt' if sigma sub b > 2 sigma sub sl . Clustering of particles will occur for interactions of particles giving misorientations such that sigma sub b < 2 sigma sub sl . Serial sectioning of stir-cast microstructures has revealed a great deal of interconnection of particles which on a single plane of polish appear separate. Partial homogenization of stir-cast and quenched alloys has produced an interesting new microstructure which may have improved mechanical properties. 22 ref.--AA
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Details
- Title
- Structure and Segregation of Stir-Cast Aluminium Alloys
- Creators
- H LeeR DohertyE FeestJ Titchmarsh
- Publication Details
- Solidification Technology in the Foundry and Cast House; Coventry; England; 15-17 Sept. 1980, pp.119-125
- Resource Type
- Conference proceeding
- Language
- English
- Academic Unit
- [Retired Faculty]; Materials Science and Engineering
- Identifiers
- 991021890002704721