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排序方式: 共有401条查询结果,搜索用时 15 毫秒
1.
Agnieszka M. Wusatowska-Sarnek Martin J. Blackburn Mark Aindow 《Materials Science and Engineering: A》2003,360(1-2):390-395
Methods are described for sample preparation of polycrystalline Ni-based superalloys in order to perform a detailed microstructural characterization. Specific techniques for the precise definition of the various phases present are outlined and these are shown to be useful for the measurement of size, volume fractions and distribution. A number of optical, scanning and transmission microscopy techniques are used to provide the necessary information. 相似文献
2.
A. Moran C. Madden R. Rebis R. Payne M. A. Matteson 《Journal of Thermal Spray Technology》1994,3(2):197-198
Over the past five years, the Annapolis Detachment, Carderock Division, Naval Surface Warfare Center (formerly David Taylor
Research Center) has established a state- of- the- art spray forming facility for the study and exploitation of this near
net shape manufacturing process. Spray forming is a single step gas atomization/deposition process which yields ferrous and
nonferrous, near final shape, near fully dense preforms that has proven to be a viable and cost effective alternative to conventional
metalworking technology for the production of material preforms with properties surpassing those of their cast and wrought
counterparts. Current programs at Carderock Divison Naval Surface Warfare Center are aimed at optimization of the process,
certification of the spray formed products and industrialization of the technology. 相似文献
3.
4.
The short-time hot-corrosion behavior of six industrial nickel-base superalloys was investigated with static deposits of Na2SO4 or NaCl or both in still air. The oxidation kinetics and scale morphologies were measured with traditional laboratory techniques-thermobalance, metallography, electron microprobe, and x-ray analyses. Susceptibility to hot corrosion was found to be correlated to the type of scale produced during simple oxidation. Alloys forming an A12O3 scale were found to be susceptible to Na2SO4 deposits, independent of their chromium content. The quantity of Na2SO4 deposit dictated the nature of the attack and, under certain conditions, the refractory element alloy additions appeared to play an essential role. Alloys containing Cr2O3 or TiO2 in the simple oxidation scale proved to be sensitive to NaCl attack. Again, the severity of the attack within the susceptible alloy group was not related to the chromium or titanium content. Although less intensive than the Na2SO4 -induced hot corrosion, NaCl contaminations provoked extensive spalling. All of the hotcorrosion types encountered in this study were interpreted in the light of existing theories.Supported by the Délégation Générale à la Recherche Scientifique et Technique. 相似文献
5.
两种Ni-Cr-Co基高温合金的凝固偏析及其对Rayleigh数的影响 总被引:1,自引:1,他引:1
利用SEM和EDAX研究了2种Ni-Cr-Co基高温合金GH742和GH738凝固过程中组织、液相成分变化,用图像分析软件测定了各温度下的液相分数,并计算了2种合金凝固过程中液相密度差和相对Rayleigh数变化。结果表明,GH742凝固过程中主要是Cr、Co和Nb的偏析,GH738合金凝固过程中主要是Cr、Co和Ti的偏析;GH742和GH738合金凝固过程中都存在着液相密度反转,后者密度差的绝对值较大;GH738合金相对Rayleigh数绝对值的最大值是GH742的3.5倍,凝固时更易形成黑斑。 相似文献
6.
E Fras E Guzik W Kapturckiewicz H.F López 《Journal of Materials Engineering and Performance》1996,5(1):103-110
Directional solidification was used to produce turbine blades by the Bridgman method. NITAC alloys with various carbon contents
were investigated; the optimum range was found to be 0.40 to 0.48%. Within this range, except for the blade locking piece
edges, the blade structure consisted predominantly of aligned eutectics. The in- situ eutectics were aligned tantalum fibers
embedded in a γ- phase matrix. The blades were produced using an alloy displacement rate of 1.86 x 10
- 6
m/s. Measurements of fiber spacings along the blade height indicated that the rate of displacement of the solidification front
exhibited some variations. These variations were closely associated with dimensional changes in the turbine blade cross sections. 相似文献
7.
Alloy 903 and Alloy 909 are well-known Fe-Co-Ni-Al-Ti-Nb alloys with controlled low thermal expan-sion, but they have some
properties that can be improved. To improve stress-accelerated grain boundary oxidation embrittlement of Alloy 903 and instability
of theγ phase of alloy 909, two new alloys with good stress-rupture ductility, high creep-rupture strength, high tensile strength
at high temperature, and good controlled thermal expansion were developed. These property improvements were accomplished by
the combination of optimizing the Fe-Co-Ni ratio of the matrix and stabilizing theγ phase with the addition of aluminum. 相似文献
8.
PROPERTIES, WELDABILITY AND APPLICATIONS OF ADVANCED WROUGHT SUPERALLOYS FOR GAS TURBINE ENGINES 总被引:1,自引:0,他引:1
D.L.Klarstrom V.R.Ishwar M.D.Rowe 《金属学报(英文版)》2005,18(1):1-14
Alloy selection and alloy design both require consideration of an array of material attributes, including in-service properties, weldability and fabricability. Critical properties of advanced wrought superaUoys for gas turbine applications include high temperature strength, thermal stability, oxidation resistance and fatigue resistance. In this paper, the properties of twelve wrought solid-solution-strengthened and six age-hardenable superalloys are compared. Weldability is an important attribute and can be a major limiting factor in the use of certain alloys. Weldability test methods are discussed and the resistance of alloys to solidification cracking and strain-age cracking is compared. The use of weldability testing in the development of modern wrought superalloys is discussed with several examples cited. Finally, alloy selection for gas turbine components is outlined, taking into account both alloy properties and fabricability. 相似文献
9.
The effects of alloy 718 microstructure on hydrogen embrittlement susceptibility and tensile fracture mode were assessed through slow strain rate tensile testing and fracture surface analysis. Alloy 718 was annealed and aged to produce microstructures with variations in grain size and amount of grain boundary precipitates. Furthermore, the different ageing conditions likely resulted in differences in volume fractions and sizes of γ′ and γ′′ precipitates. The extent of grain boundary precipitation had the strongest effect on hydrogen embrittlement susceptibility, while grain size did not have any significant effect. Hydrogen embrittlement susceptibility was also correlated with differences in strength level, which was primarily controlled by the γ′ and γ′′ precipitate populations. 相似文献
10.
I. Povstugar C. H. Zenk R. Li S. Neumeier O. Dolotko 《Materials Science & Technology》2016,32(3):220-225
Novel Cr containing Co-Al-W base superalloys were studied by atom probe tomography and neutron diffraction. Cr is found to predominantly partition to the γ matrix and decrease partitioning of W to γ′. Furthermore, Cr significantly enhances the γ′ volume fraction, decreases the γ/γ′ lattice misfit and deteriorates the creep resistance. Addition of Ni to the Cr containing alloys affects partitioning of W and Al, further decreases the lattice misfit and results in the formation of irregularly shaped precipitates. Al, W and Cr tend to occupy the ‘B'sublattice in the γ′-A3B phase (L12 type), while Co and Ni reside in the ‘A' sublattice. 相似文献