STP890

    Effect of Compositional Variations on the Microstructure and Properties of Rapidly Solidified Al-3Li Alloys

    Published: Jan 1986


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    Abstract

    The quantitative effects of stepwise additions of the precipitation-strengthening element copper, the solid-solution-strengthening element magnesium, and the substructure-refining element zirconium on the microstructures and peak-aged mechanical properties of rapid solidification processed (RSP) Al-3Li alloys have been determined. Additions of 0.2 to 0.5% zirconium by weight produce a 1.4 to 1.9-μm diameter, fully recovered subgrain structure in Al-3Li-Zr extrusions and raise the peak-aged yield stress of Al-3Li by 100 to 140 MPa. The addition of 1% magnesium raises the yield stress of Al-3Li-0.2Zr by 35 MPa, but a further addition to 2% has no effect. Additions of 1 to 2% copper to Al-3Li-0.2Zr raise the yield stress by 45 MPa per weight percent copper and render the peak-aged mechanical properties of the alloy sensitive to variations in solutiontreatment temperature and process stretch. Improvements in the properties of RSP Al-3Li-Cu-Zr alloys, in comparison with those measured by previous investigators, are related to improvements in consolidation processing and, in particular, to effective disintegration of oxide layers on the RSP particulates. Al-3Li-1Mg-0.2Zr and Al-3Li-2Cu-0.2Zr are promising substitutes for commercial 2XXX and 7XXX aluminum alloys, respectively, at 10 to 11% lower density levels.

    Keywords:

    aluminum alloys, powder metallurgy, rapid solidification processing, aluminum, microstructure, mechanical properties, alloying effects, heat treating


    Author Information:

    Meschter, PJ
    Senior scientist and scientists, McDonnell Douglas Research Laboratories, St. Louis, MO

    Pao, PS
    Senior scientist and scientists, McDonnell Douglas Research Laboratories, St. Louis, MO

    Lederich, RJ
    Senior scientist and scientists, McDonnell Douglas Research Laboratories, St. Louis, MO

    O'Neal, JE
    Senior scientist and scientists, McDonnell Douglas Research Laboratories, St. Louis, MO


    Paper ID: STP33047S

    Committee/Subcommittee: B09.03

    DOI: 10.1520/STP33047S


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