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Author: WL. Bell Publisher: ISBN: Category : Ion bombardment Languages : en Pages : 13
Book Description
The effect of reactor irradiation on the microstructural stabilities of several high-nickel-content superalloys was evaluated by transmission electron microscopy. The alloys include Nimonic PE16 and the Inconel alloys 706 and 718. Specimens were irradiated in sealed, unstressed, sodium-filled capsules in the Experimental Breeder Reactor II. Irradiation temperatures ranged from 399 to 649°C (750-1200°F); specimens accumulated a peak fluence of 6 x 1022 n/cm2, E > 0.1 MeV. While little or no microstructural changes were observed in Nimonic PE16, the Inconels exhibited overaging precipitation effects -- in particular, the formation of the stable overaging precipitate, eta -- which increased with temperature in the range studied. Inconel 706 exhibited the more pronounced overaging effects, i.e., larger and coarser eta plates, consistent with its higher titanium-to-aluminum ratio. In general, the precipitation features noted in all three alloys were similar to those observed in identical material after ion bombardment with high energy nickel ions at comparable temperatures. (The latter work was presented in a similar symposium and published in ASTM STP 611). The ion bombardment work has thus correctly predicted the microstructural response of these alloys to fast neutron irradiation.
Author: WL. Bell Publisher: ISBN: Category : Ion bombardment Languages : en Pages : 13
Book Description
The effect of reactor irradiation on the microstructural stabilities of several high-nickel-content superalloys was evaluated by transmission electron microscopy. The alloys include Nimonic PE16 and the Inconel alloys 706 and 718. Specimens were irradiated in sealed, unstressed, sodium-filled capsules in the Experimental Breeder Reactor II. Irradiation temperatures ranged from 399 to 649°C (750-1200°F); specimens accumulated a peak fluence of 6 x 1022 n/cm2, E > 0.1 MeV. While little or no microstructural changes were observed in Nimonic PE16, the Inconels exhibited overaging precipitation effects -- in particular, the formation of the stable overaging precipitate, eta -- which increased with temperature in the range studied. Inconel 706 exhibited the more pronounced overaging effects, i.e., larger and coarser eta plates, consistent with its higher titanium-to-aluminum ratio. In general, the precipitation features noted in all three alloys were similar to those observed in identical material after ion bombardment with high energy nickel ions at comparable temperatures. (The latter work was presented in a similar symposium and published in ASTM STP 611). The ion bombardment work has thus correctly predicted the microstructural response of these alloys to fast neutron irradiation.
Author: H. Takahashi Publisher: ISBN: Category : Depletion Languages : en Pages : 10
Book Description
Microstructural changes and solute segregation in austenitic Fe-Cr-Mn-Ni alloys have been studied after neutron irradiation to 25 dpa (maximum) in FFTF/MOTA. Voids were nucleated in all of the specimens in the temperature range of 420 to 650°C, and a swelling peak was observed to form at 550°C. The void suppression effect of nickel additions did not occur in these alloys. Precipitates were formed in the matrix and/or on grain boundaries and were mostly identified as M23C6. The composition in the grain boundary area changed, and the chromium (Cr) concentration near the precipitates became higher. On the other hand, manganese and chromium were depleted, and nickel was enriched in the grain boundary area, but without precipitation. Other phases such as ferrite and sigma could not be recognized. Thus, it was revealed that the addition of nickel to Fe-Cr-Mn alloy stabilizes the austenite even in the grain boundary area where segregation is marked.
Author: DJ. Michel Publisher: ISBN: Category : Electron microscopy Languages : en Pages : 18
Book Description
The microstructure and microhardness of niobium and commercial prototype niobium-base alloys have been investigated following fast neutron irradiation to a fluence of 1.1 x 1022 neutrons (n)/cm2 (0.1 MeV), 4 displacements per atom (dpa), at 482°C. The purpose of this work was to determine the effects of molybdenum and zirconium alloy additions on the resistance of niobium-base alloys to neutron irradiation. Neutron irradiation of the niobium and Nb-1Mo alloy produced very small voids whose mean diameters were in the range of 30 to 35 Å. In all other alloys, however, no voids were observed and the principal effect of the neutron irradiation was to form a high density of 30 to 40 Å diameter dislocation loops which are believed to be primarily of interstitial character. The effect of fast neutron irradiation was to increase the microhardness of both niobium and all its alloys, with the largest increase in the Nb-1Zr alloy and the smallest increase in the ternary Nb-5Mo-1Zr alloy. Previous work on niobium and Nb-1Zr alloy has shown that a vacancy trapping mechanism is particularly effective at irradiation temperatures up to 600°C for fast neutron fluences of 2.5 x 1022 n/cm2 (0.1 MeV). The observation from the present experiments that molybdenum and zirconium additions were effective in the suppression of void formation suggests that a vacancy trapping mechanism was operative in the present alloys. The smaller hardness increase observed for the ternary alloys suggests that these alloys may maintain good engineering properties in addition to their improved resistance to void formation.
Author: Craig M. Eucken Publisher: ASTM International ISBN: 080311463X Category : Nuclear fuel claddings Languages : en Pages : 794
Book Description
The proceedings of the Ninth International Symposium on [title], held in Kobe, Japan, November 1990, address current trends in the development, performance, and fabrication of zirconium alloys for nuclear power reactors. the bulk of the most recent work on zirconium alloy behavior has concerned corr
Author: Roger E. Stoller Publisher: ASTM International ISBN: 080311477X Category : Materials Languages : en Pages : 1315
Book Description
Symposium held in Nashville, Tennessee, June 1990. Almost two-thirds of these 91 papers are authored by researchers outside of the US (including information on research in the former USSR, Japan, and Europe). Topics include: current commercial power reactor systems; microstructural characterization
Author: H. Kinoshita Publisher: ISBN: Category : Alloying element Languages : en Pages : 9
Book Description
To investigate the effect of alloying elements on void formation and precipitation during neutron irradiation, vanadium and vanadium based alloys were irradiated in the experimental fast breeder reactor "JOYO" up to 6 x 1025 n/m2 at 670 to 870 K. Alloying elements were selected on the basis of volume size factors: carbon for an interstitial atom, chromium for an undersized substitutional atom and titanium and molybdenum are oversized ones. Voids were formed in all materials except in V-Ti alloys. The V-Cr alloy shows inhomogeneous void formation, and the swelling was larger compared to other alloys. The void formation was related to the radiation-induced precipitates which nucleated on dislocations. In the matrix of the V-Mo alloy, the precipitation was not confirmed, and homogeneous void formation occurred so the swelling was not large. Void formation and precipitation are discussed on the basis of alloying effects.
Author: Publisher: ISBN: Category : Languages : en Pages : 9
Book Description
GlidCop{trademark} internally oxidized copper alloys remain the leading candidates for high heat flux applications in fusion reactor. This paper presents the microstructural changes incurred in three GlidCop{trademark} alloys exposed to long term, high temperature neutron irradiation. Irradiation at high temperature produced a microstructure containing a much lower dislocation density than the unirradiated specimens. Although 10--50 nm size triangular oxide particles were observed in areas with a very low number density of particles, spherical oxide particles on the order of 5--7 nm in diameter, thought to be CuAl2O4, were the predominant morphology. The changes in grain size distribution, dislocation density, and precipitate type and distribution saturate in the range of 34 to 50 dpa, as reflected in the saturation of mechanical properties.
Author: BA. Loomis Publisher: ISBN: Category : Edema Languages : en Pages : 12
Book Description
The microstructures in V-15Cr-5Ti, V-10Cr-5Ti, V-3Ti-lSi, V-15Ti-7.5Cr, and V-20Ti alloys were examined by transmission electron microscopy after neutron irradiation at 600°C to 21 to 84 atom displacements per atom in the Materials Open Test Assembly of the Fast Flux Test Facility. The microstructures in these irradiated alloys were analyzed to determine the radiation-produced dislocation density, precipitate number density and size, and void number density and size. The results of these analyses were used to compute increases in yield stress and swelling of the irradiated alloys. The computed increase in yield stress was compared with the increase in yield stress determined from tension tests on these irradiated alloys. This comparison made it possible to evaluate the influence of alloy composition on the evolution of radiation-damaged microstructures and the resulting tensile properties.
Author: WL. Bell
Author: WL. Bell
Author: H. Takahashi
Author: DJ. Michel
Author: Craig M. Eucken
Author: Roger E. Stoller
Author: Jian Gan
Author: H. Kinoshita
Author: 
Author: BA. Loomis
Author: F. A. Garner