Abstract
Two Al-rich Al-Ta alloys containing by weight 3 and 6 pct Ta have been rapidly solidified from the melt using the ‘gun’ technique. The microstructures and the crystal structures of the phases in the as-solidified as well as those formed on subsequent decomposition of the supersaturated solid solution have been characterized. A supersaturated solid solution was obtained in both the alloys in the as-solidified condition indicating a solid solubility extension of Ta in Al to almost 6 wt pct. The supersaturated solid solutions formed in both the alloys have been found to be quite stable up to 673 K (for 1 hour). Annealing at higher temperatures resulted in the formation of rod-shaped precipitates inside the grains and massive precipitates along grain boundaries. The rod-shaped precipitates arranged in a regular pattern constitute a new metastable intermediate phase Al7Ta having an ordered structure. The massive precipitates which form along grain boundaries constitute the equilibrium Al3Ta phase with a tetragonal crystal structure. The transformation behavior and the morphology of the transformation products are detailed in this paper.
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Singh, S., Lele, S. & Suryanarayana, C. Microstructural characterization of rapidly solidified Al-Ta alloys. Metall Trans A 18, 1915–1922 (1987). https://doi.org/10.1007/BF02647021
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DOI: https://doi.org/10.1007/BF02647021