Precipitation of dispersoids in aluminum alloys
The influence of alloy composition and preheat treatment on the precipitation of the metastable Al{sub 3}Zr, {beta}{prime}, phase in ternary alloys and the subsequent recrystallization behavior was investigated. The ternary alloys contained zirconium and one of the following elements: copper, manganese, zinc, or silicon. Diffusion couples were constructed and the values for the interdiffusion coefficient for several elements in aluminum were calculated. The calculated values for the interdiffusion coefficients were used in a finite difference model for the prediction of the homogenization of an as-cast microstructure during preheating. {beta}{prime} was observed to precipitate on defects such as dislocations and low-angle boundaries when a critical solute level in all ternary alloys was reached. The critical solute level was system dependent. Homogeneous nucleation of {beta}{prime} occurred in Al-Si-Zr alloys. In Al-Zn-Zr alloys the shape of the {beta}{prime} deviated from its usual spherical shape to a cube shape when the zinc level exceeds approximately 4 wt. %. When compared to other alloying element additions, small amounts of silicon (between 0.25 and 0.5 wt %) had the greatest influence on not only the recrystallization behavior of the alloy, but also the precipitation of {beta}{prime}.
- Research Organization:
- Georgia Inst. of Tech., Atlanta, GA (United States)
- OSTI ID:
- 5636330
- Country of Publication:
- United States
- Language:
- English
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