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  • 1
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    High temperature inelastic deformation under uniaxial loading - Theory and experiment (1989)
    In:  Other Sources
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    Publication Date: 2019-07-12
    Description: The elevated-temperature uniaxial inelastic deformation behavior of an Ni-base alloy, B1900 + Hf, is investigated by performing isothermal tensile, creep, cyclic, stress relaxation, and thermomechanical fatigue tests. The range of strain rates examined is from 10 to the -7th to 100 per sec, while the test temperatures range from 25 to 1093 C. This extensive constitutive data base has been used for evaluating the unified constitutive models of Bodner and Partom (1972) and of Walker (1972) which apply for the small-strain regime. Comparison of test results with independent model predictions indicates good agreement over a broad range of loading conditions, demonstrating the applicability of the unified-constitutive-equation approach for describing the strongly nonlinear and temperature-dependent response of meals under a wide range of deformation and thermal histories. Thus the results give confidence that the unified approach is an effective and efficient approach in which complex history-dependent thermoviscoplastic flow can be represented within a single inelastic strain-rate term.
    Keywords: METALLIC MATERIALS
    Type: ASME, Transactions, Journal of Engineering Materials and Technology (ISSN 0094-4289); 111; 345-353
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  • 2
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    High temperature inelastic deformation of the B1900 + Hf alloy under multiaxial loading - Theory and experiment (1990)
    In:  Other Sources
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    Publication Date: 2019-07-12
    Description: The multiaxial deformation behavior of the Ni-based alloy B1900 + Hf has been studied at elevated temperatures in the range of 649-982 C. Combined tension/torsion cyclic tests were performed on thin-wall tubular specimens under both in-phase and out-of-phase strain-controlled loading cycles. Both straining conditions resulted in stress loci of comparable magnitude, exhibiting no difference in cyclic hardening response. A phase angle was observed between the deviatoric stress and the incremental plastic strain vectors during 90-deg out-of-phase strain cycling, and nonproportional stress relaxation occurred under biaxial strain hold. The overall results have been used to assess the flow law, the hardening equations, and the applicability of the J2-based, elastic-viscoplastic model of Bodner-Partom (1979) for multiaxial loading conditions. The overall agreement between theory and experiment is good. Discrepancies are discussed in relation to micromechanical considerations.
    Keywords: METALLIC MATERIALS
    Type: ASME, Transactions, Journal of Engineering Materials and Technology (ISSN 0094-4289); 112; 7-14
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  • 3
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    Phenomenological modeling of hardening and thermal recovery in metals (1988)
    In:  Other Sources
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    Publication Date: 2019-07-12
    Description: Modeling of hardening and thermal recovery in metals is considered within the context of unified elastic-viscoplastic theories. Specifically, the choices of internal variables and hardening measures, and the resulting hardening response obtained by incorporating saturation-type evolution equations into two general forms of the flow law are examined. Based on the analytical considerations, a procedure for delineating directional and isotropic hardening from uniaxial hardening data has been developed for the Bodner-Partom model and applied to a nickel-base superalloy, B1900 + Hf. Predictions based on the directional hardening properties deduced from the monotonic loading data are shown to be in good agreement with results of cyclic tests.
    Keywords: METALLIC MATERIALS
    Type: ASME, Transactions, Journal of Engineering Materials and Technology (ISSN 0094-4289); 110; 1-8
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  • 4
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    Inelastic deformation under nonisothermal loading (1990)
    In:  Other Sources
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    Publication Date: 2019-07-12
    Description: The objective of this paper is to evaluate, both experimentally and analytically, the appropriate forms of the hardening evolution equations in unified constitutive models for conditions involving nonisothermal loading. Critical experiments were performed for a cast nickel-base superalloy by using variable temperature tensile, creep, and cyclic tests in the 538-982 C temperature range. These experimental results were compared with both isothermal data and predictions of the Bodner-Partom-Bodner, 1987 elastic-viscoplastic theory to assess the effects of thermal history on constitutive behavior. The results indicate that the hardening evolution equations based on isothermal data are applicable for nonisothermal loading of these precipitation strengthened alloys. Additional thermal history effect terms in the hardening evolution equations were not required beyond those accounting for the variation of material constants with temperature. Using material constants determined solely from isothermal data, the inelastic deformation behavior of B1900 + Hf subject to thermomechanical loading were adequately predicted by the Bodner-Partom model.
    Keywords: METALLIC MATERIALS
    Type: ASME, Transactions, Journal of Engineering Materials and Technology (ISSN 0094-4289); 112; 15-25
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  • 5
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    Studies on the Al2O3-Ti-Mo-Au metallization system (1975)
    In:  Other Sources
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    Publication Date: 2011-08-16
    Description: The behavior of Ti-Mo-Au metallization on Al2O3 and C has been investigated by backscattering spectrometry. Results show that Mo-Au bimetal films typically mix during deposition. Diffusion of Ti in Mo film occurs at 600 C, but is inhibited by the presence of oxygen in the Ti film. Even 1000 A of Mo is not a barrier against interdiffusion of Ti and Au during 20-min anneals at 600 C. The amount of mixing observed also depends on the nature of the substrate which supports the Ti-Mo-Au metallization.
    Keywords: METALLIC MATERIALS
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