STP683

    Microstructure and Tensile Properties of Heavily Irradiated 1100-0 Aluminum

    Published: Jan 1979


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    Abstract

    Microstructural changes and the resulting tensile properties of commercial-purity (1100 grade) aluminum were measured after neutron irradiations up to 1.4 × 1027 neutrons (n)/m2 (E > 0.1 MeV) and 2.3 × 1027 n/m2 (E > 0.025 eV) at ∼ 328 K (0.35 Tm), corresponding to displacement levels of 200 displacements per atom and the generation of 5.5 weight percent silicon. The material displayed up to about 8 percent swelling. Microstructural features included dislocation tangles, a precipitate of elemental silicon, and heterogeneously distributed voids coated with silicon. Alongside grain boundaries were sheets of large voids. These microstructural features are shown to be responsible for increasing the 0.2 percent flow stress and the ultimate tensile strength at 323 K by factors of 5 and 3 to values of 220 and 250 MPa, respectively, and by factors of 6.5 and 3.5 to about 190 MPa at 423 K (0.45 Tm). Elongation was reduced at 323 K from 32 percent to a plateau at 12 percent in the fluence range 4 × 1025 n/m2 to 7 × 1026 n/m2 (>0.1 MeV), followed by a sharp fall to 4 percent at the highest fluences, the latter concomitant with a change to intergranular-type fracture. In the 423 K tests the elongation declined from 56 to 4 percent at the highest fluences where intergranular-type fracture prevailed. Most of this loss in ductility is accountable in terms of dispersion hardening through changes in strain-hardening parameters. It is suggested that the apparent intergranular fractures are caused by tearing of sheets of voids adjacent to grain boundaries.

    Keywords:

    commercial aluminum, neutron irradiation, high fluence, microstructure, voids, silicon precipitate, tension tests, strengthening, ductility loss, fracture (material)


    Author Information:

    Farrell, K
    Senior research staff, Oak Ridge National Laboratory, Oak Ridge, Tenn.

    Richt, AE
    Senior research staff, Oak Ridge National Laboratory, Oak Ridge, Tenn.

    Union Carbide Corp., South Charleston, W. Va.


    Paper ID: STP38179S

    Committee/Subcommittee: E10.07

    DOI: 10.1520/STP38179S


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