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  • METALLIC MATERIALS  (12)
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  • 1
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    Fatigue crack growth and low cycle fatigue of two nickel base superalloys (1983)
    In:  CASI
    Details
    Publication Date: 2019-06-28
    Description: The fatigue crack growth and low cycle fatigue behavior of two P/M superalloys, Rene 95 and Astroloy, in the hot isostatically pressed (HIP) condition, was determined. Test variables included frequency, temperature, environment, and hold times at peak tensile loads (or strains). Crack initiation sites were identified in both alloys. Crack growth rates were shown to increase in argon with decreasing frequency or with the imposition of hold times. This behavior was attributed to the effect of oxygen in the argon. Auger analyses were performed on oxide films formed in argon. Low cycle fatigue lives also were degraded by tensile hold, contrary to previous reports in the literature. The role of environment in low cycle fatigue behavior is discussed.
    Keywords: METALLIC MATERIALS
    Type: NASA-CR-174534 , NAS 1.26:174534
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  • 2
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    Effects of temperature and hold times on low cycle fatigue of Astroloy (1986)
    In:  Other Sources
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    Publication Date: 2019-06-28
    Description: Low cycle fatigue (LCF) and creep-fatigue-environment interactions of HIP Astroloy were studied at 650 C and 725 C. The results showed that the model proposed by Kaisand and Mowbray (1979) was successful in predicting the magnitude and trend of the fatigue crack growth rate from LCF data. Raising the temperature from 650 C to 725 C did not change the fracture mode, while employing tensile hold caused a change in fracture mode and was more damaging than raising the temperature by 75 C. All samples displayed multiple fracture origins, which is initiated transgranularly in continuous cycling tests and intergranularly in hold time tests. An examination of the secondary crack showed no apparent creep damage. Oxidation in high purity argon appeared to be the major factor in LCF life degradation due to hold time.
    Keywords: METALLIC MATERIALS
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  • 3
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    The effects of frequency and hold times on fatigue crack propagation rates in a nickel base superalloy (1983)
    In:  Other Sources
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    Publication Date: 2019-06-28
    Description: The elevated temperature cyclic crack propagation behavior of a nickel base superalloy, Astroloy, produced by a hot isostatic pressing technique has been evaluated. Environment, frequency and peak load hold times have been controlled to evaluate the effects of creep and environment of fatigue crack propagation rates at several temperatures.
    Keywords: METALLIC MATERIALS
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  • 4
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    Analysis of liquid metal embrittlement from a bond energy viewpoint (1975)
    In:  Other Sources
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    Publication Date: 2019-06-27
    Description: Absorption induced embrittlement of solid metals by certain liquid metals is analyzed through an Engel-Brewer calculation of the solid-liquid interaction energy, and of the effect of the latter in reducing fracture surface energy. The reduction in fracture surface energy is estimated by comparison of the electronic contribution to the solid-liquid interaction energy with solid-solid bond energy for some 40 liquid-solid couples. Regular solution theory is used to estimate mutual solubility as the relative difference in parameter values. Embrittlement can be predicted by using reduction in fracture surface energy and solubility parameter difference as critical variables. The effect of solute additions to the liquid on the degree of embrittlement is interpreted via the same two variables; the principal effect of solutes is to modify solubility relationships at the solid-liquid interface.
    Keywords: METALLIC MATERIALS
    Type: Metallurgical Transactions A - Physical Metallurgy and Materials Science; 6A; Jan. 197
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  • 5
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    Mercury embrittlement of Cu-Al alloys under cyclic loading (1977)
    In:  Other Sources
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    Publication Date: 2019-06-27
    Description: The effect of mercury on the room temperature, high cycle fatigue properties of three alloys: Cu-5.5 pct Al, Cu-7.3 pct Al, and Cu-6.3 pct Al-2.5 pct Fe has been determined. Severe embrittlement under cyclic loading in mercury is associated with rapid crack propagation in the presence of the liquid metal. A pronounced grain size effect is noted under mercury, while fatigue properties in air are insensitive to grain size. The fatigue results are discussed in relation to theories of adsorption-induced liquid metal embrittlement.
    Keywords: METALLIC MATERIALS
    Type: Metallurgical Transactions A - Physical Metallurgy and Materials Science; 8A; June 197
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  • 6
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    Effect of chromium on low-temperature deformation of high-purity iron (1976)
    In:  Other Sources
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    Publication Date: 2019-06-27
    Description: A series of very low interstitial Fe-Cr alloys containing 0, 1, 3, 5, and 10 wt% Cr were prepared by vacuum melting and fabricated under argon to 1.83 mm diam wires exposed in an alumina system to wet hydrogen for 200 h at 1423 K followed by 1000 h in ZrH2-purified hydrogen at 1573 K. The wires were then transverse-rolled into thin sheet and cut into tensile specimens subjected to electropolishing and strained to fracture in a series of cryogenic baths ranging from 4.2 K to room temperature. It is shown that small Cr additions lower the twinning stress so that yielding occurs by twinning rather than by slip. Cr in amounts up to 10 wt% has little effect on the yield strength of high-purity Fe between 147 and 300 K, and ductility is not greatly affected at any test temperature. Higher solute contents provide appreciable strengthening only at temperatures of 112 K and below.
    Keywords: METALLIC MATERIALS
    Type: Metallurgical Transcations A - Physical Metallurgy and Materials Science; 7A; Feb. 197
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  • 7
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    The influence of growth rate and temperature on high cycle fatigue of Al-Al3Ni (1976)
    In:  Other Sources
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    Publication Date: 2019-06-27
    Description: High-cycle fatigue tests have been conducted on specimens of an Al-Al3Ni eutectic alloy, unidirectionally solidified at selected rates from 0.000139 to 0.3 cm/sec. Tests were conducted in air at 298, 458 and 683 K. Room temperature fatigue lives were independent of growth rate at low solidification rates but were markedly improved in samples grown at 0.3 cm/sec. Materials grown at 0.00833 cm/sec exhibited fatigue lives similar to those of the lower growth rates, despite gross misalignment due to cellular growth. The dependence of fatigue life on growth rate at elevated temperatures appears to be due primarily to differences in cyclic creep rates as a result of varying interfiber spacings. Crack initiation and propagation mechanisms were established by metallographic and fractographic examination. Dislocation substructure-fiber interactions were studied by transmission electron microscopy.
    Keywords: METALLIC MATERIALS
    Type: Metallurgical Transactions A - Physical Metallurgy and Materials Science; 7A; May 1976
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  • 8
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    The influence of growth speed, orientation and environment on fracture of aligned Al-CuAl2 (1977)
    In:  Other Sources
    Details
    Publication Date: 2019-06-27
    Description: There has been considerable interest in the mechanical properties of aligned eutectics as functions of microstructure, orientation between reinforcement and stress axis, and temperature of testing. However, little is known about the behavior of these alloys in aggressive environments, such as liquid metals, with the exception of a recent paper on embrittlement of several eutectic alloys in gallium and gallium-indium alloys. This paper is concerned with the effects of a liquid Ga-16%In solution on tensile behavior of an aligned Al-CuAl2 eutectic.
    Keywords: METALLIC MATERIALS
    Type: Scripta Metallurgica; 11; Jan. 197
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  • 9
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    The influence of hold times on LCF and FCG behavior in a P/M Ni-base superalloy (1984)
    In:  Other Sources
    Details
    Publication Date: 2019-07-13
    Description: The relative importance of creep and environmental interactions in high temperature fatigue behavior has been investigated for as-HIP Rene 95. Strain-controlled low cycle fatigue and load-controlled fatigue crack growth tests were performed at elevated temperatures in argon, followed by fractographic analyses of the fracture surfaces by scanning electron microscopy. Fatigue lives were drastically reduced and crack growth rates increased one hundred fold as a result of superposition of hold times on continuous cycling. A change in fracture mode with hold time also was noted. Chromium oxide was detected on the fracture surface by Auger electron spectroscopy. The drastic changes in fatigue resistance due to hold times were attributed primarily to environmental interactions with fatigue processes.
    Keywords: METALLIC MATERIALS
    Type: Superalloys 1984; Oct 07, 1984 - Oct 11, 1984; Champion, PA; United States
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  • 10
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    High-temperature ordered intermetallic alloys II; Proceedings of the Second Symposium, Boston, MA, Dec. 2-4, 1986 (1987)
    In:  Other Sources
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    Publication Date: 2019-07-13
    Description: The papers presented in this volume provide on overview of recent theoretical and experimental research in the field of high-temperature ordered intermetallic alloys. The papers are gouped under the following headings: ordering behavior and theory, microstructures, mechanical behavior, alloy design and microstructural control, and metallurgical properties. Specific topics discussed include antiphase domains, disordered films and the ductility of ordered alloys based on Ni3Al; kinetics and mechanics of formation of Al-Ni intermetallics; deformability improvements of L1(2)-type intermetallic compounds; B2 aluminides for high-temperature applications; and rapidly solidified binary TiAl alloys.
    Keywords: METALLIC MATERIALS
    Type: High-temperature ordered intermetallic alloys II; Dec 02, 1986 - Dec 04, 1986; Boston, MA; United States
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