Abstract
The microstructure of as-cast Cu-AI-Ni alloys, based on copper containing 9 to 10 wt pct Al and up to 5 wt pct Ni, has been examined. The development of the microstructure on continuous cooling has also been investigated. For alloys with 9.2 to 9.3 wt pct Al, and less than 1 wt pct Ni, the as-cast microstructure consists of proeutectoid α solid solution, α + γ2 eutectoid, and martensitic β. If the nickel content is more than 2.5 wt pct, the α + γ2 eutectoid is replaced by α + β ′2 eutectoid, and no martensitic β is observed in the as-cast alloys. The morphologies of the β ′2 and γ2 eutectoid phases are similar; both have the Kurdjumov-Sachs (K-S) orientation relationship with the a phase. Two eutectoid reactions, involving β to α + γ2 and β to α + β′2, have been observed in an alloy containing 9.7 wt pct Al and 2.7 wt pct Ni. When both eutectoid reactions occur, the Nishiyama-Wassermann (N-W) orientation relationship exists between γ2 or β ′2 and the α phase. During continuous cooling, proeutectoid α solid solution is the first phase to precipitate from the high-temperature β phase. The β to α + β ′2 eutectoid reaction starts at higher temperatures than the β to α + γ2 reaction. Tempering of the as-cast alloys results in the elimination of the martensitic β.
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Y.S. SUN formerly Research Associate with the Manchester Materials Science Centre.
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Sun, Y.S., Lorimer, G.W. & Ridley, N. Microstructure and its development in Cu-Al-Ni alloys. Metall Trans A 21, 575–588 (1990). https://doi.org/10.1007/BF02671930
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DOI: https://doi.org/10.1007/BF02671930