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31.
The superplastic formability of SP- lnconel 718 superalloy was evaluated using the argon blowing method. Relationships among
superplastic forming parameters (forming temperature, argon pressure, and forming time) and specific dome height (dome height/workpiece
diameter) were investigated, as were changes in material properties after superplastic forming. Experimental results showed
the optimum forming temperature range for SP- lnconel 718 to be between 975 and 995 °C. During the superplastic forming process,
5- phase precipitates formed at grain boundaries and limited the grain growth, which is considered beneficial for superplastic
deformation. On the other hand, increasing the forming deformation also increased the formation of cavities, which can be
attributed to the existence of niobium- rich inclusions. This degraded the superplasticity of the superalloy. Electrochemical
tests showed that the corrosion resistance of SP- lnconel 718 after superplastic forming worsened because of the existence
of both S- phase precipitates and niobium- rich inclusions. 相似文献
32.
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34.
H. Mughrabi H. Biermann T. Ungar 《Journal of Materials Engineering and Performance》1993,2(4):557-564
The γ-γ lattice mismatch of specimens of the monocrystalline nickel-base superalloy SRR 99 has been measured by a high-resolution
X-ray diffraction technique for the undeformed state and after high-tem-perature creep deformation. During creep deformation
beyond the minimum creep rate (total strain =0.5%), the lattice mismatches, measured in and perpendicular to the [001] stress
axis, respectively, un-dergo changes in opposite directions. This reflects the buildup of a complex deformation-induced triaxial
state of internal stress in the phases y and γ. The overall resolved shear stresses that act in γ and y due to the combined
action of the external and internal stresses are estimated, and the conditions under which cutting of the γ phase by dislocations
should occur are discussed. 相似文献
35.
Jung-Chel Chang Cheol Choi Jae-Chul Kim Young-Hoon Yun 《Journal of Materials Engineering and Performance》2003,12(4):420-425
Effects of the hot-isostatic pressing (HIP) process on microstructures and mechanical properties of Ni-base single crystal
superalloy CMSX-4 were investigated. In the overall heat treatment process, the HIP treatment remarkably induced the healing
behavior of micropores and decreased the pore size and porosity of superalloy CMSX-4 compared with normally treated specimens.
The microstructure of γ′ phase after the HIP process showed rather a coarsening tendency and could be developed by the partially solution and aging
treatment. Consequently, the elimination of cast micropores using the HIP step resulted in the inhibition of crack initiation
in microstructure and improved the stress-rupture lives of Ni-base single crystal superalloy by 185%. 相似文献
36.
根据已知镍基合金成分和γ′相成分,运用分层宽容多目标优化法,分别计算了γ相成分及γ′相含量.优化测算过程的实现是通过建立使杠杆定律等式两端数值差最小和两相共格错配度最小的目标函数,并通过设置γ′相含量和基体相成分取值范围的约束条件而实现的.验证了该方法的可行性和准确性. 相似文献
37.
IntroductionSLlperalloyandheat-resistingsteelarenowwidelyusedasstructurematerialsinaerospace,a\-lationalldshipbuildingindustries.Nickel-basesuperalloywasfirstlyrevealedasanengineeringmaterialduringtheearly1960swhenitwasrecognizedasbeingsuitableforllledium-temperaturegasturbinel'l.Now.nickel-basesuperalloyhasbeenpracticallyusedinhigheffectiveturbinestosatisfytheincreasingdemandsforhighertemperatureenvironmentsIZI.Insomeaerospaceengines,theimpellersshouldserveattemperatureof1000C~1100C,andala… 相似文献
38.
This paper deals with an experimental investigation concerning steam reforming of methanol at 280, 340 and 380 °C over NiAl
and Ni (Au, Rh or Ir)Al layered double hydroxides (LDHs) derived catalysts. Incorporation of noble metal ions into the NiAl-LDH
framework was evidenced by XRD, TGA and TEM techniques. High selectivity to H2 and CO2 with less than 5% (volume) CO and trace CH4 was observed over the NiAl-LDH catalyst. Whereas CO and H2 are major products at lower temperatures after addition of Au, Rh and Ir to the NiAl-LDH system. They are significantly reduced
with the concomitant increase in CH4 and CO2 as the temperature increased. 相似文献
39.
Copolymerization of norbornene with norbornene terminated polystyrene macromonomer in the presence of Ni-based/MAO catalytic systems 总被引:1,自引:0,他引:1
Copolymerization of -norbornenyl polystyrene macromonomer (NBE-PS) with norbornene (NBE) using Ni-based catalysts in combination with methylaluminoxane (MAO) was investigated. The nature of the catalyst, the
of the polystyrene macromonomer as well as the [NBE-PS]/[NBE] ratio have been shown to be important parameters to obtain graft copolymers with high NBE-PS incorporation (up to 43 wt%). The compatibilization ability of these graft copolymers has been checked for PS/PNBE blends. The length of the grafts was proved not to be an important parameter to consider compatibilization of the PS/PNBE blend. 相似文献
40.
采用有限元软件对高温合金IN690管材挤压损伤进行预测,研究挤压速度对损伤的影响规律,得到不同的挤压条件下的挤压阈值。不同挤压速度下损伤的变化随着挤压速度变化呈现先增大后减小的趋势。模拟摩擦系数为0.01、0.05、0.1、0.2条件下的损伤,在摩擦系数为0.01时,坯料表面比较光滑,损伤比较轻;摩擦系数为0.2时,表面凹凸不平,损伤严重。 相似文献