Rhenium Effect on Creep Behavior of Ni-Base Superalloys

1980 ◽  
Vol 38 ◽  
pp. 330-331 ◽  
Author(s):  
L.S. Lin ◽  
A.F. Giamei ◽  
R.E. Doiron
Keyword(s):  
Single Crystals ◽  
Gauge Length ◽  
Tensile Creep ◽  
Weight Percentage ◽  
Transmission Electron ◽  
Heat Treated ◽  
Dislocation Behavior ◽  
Rhenium Addition ◽  
C 32 ◽  
Octahedral Slip

Modified MAR-M-200 single crystals with various amounts of rhenium were tested in tensile creep in <111>, <011> and <001> orientations. With the addition of rhenium, a significant improvement in creep resistance was attained. This is illustrated clearly in Figure 1. In order to understand the effect of the rhenium addition on the creep strength of Ni-base superalloy single crystals, transmission electron microscopy was used to analyze the microstructures and dislocation behavior. Creep samples with gauge length of 10 mm and diameter of 2.5 mm were tested at 900°C/380 MPa unless otherwise specified. The chemical composition of the alloy studied is 5Al-2Ti-lNb-9Cr-12(W + Re) with the balance Ni (in weight percentage). The rhenium contents were 0, 2, 1, or 6 wt. $ at the expense of tungsten. The samples were fully heat treated (l290°C/4 hrs. + 1080°C/4 hrs. + 870° C/32 hrs.) before testing. The oriented crystals (with 0 and 6 wt. $ Re, respectively) were creep tested to a strain of ~ 0.2$. Their detailed transmission microstructures are shown in Figures 2 and 3. In <111> crystals, cube slip, {001} <110> was observed while in <011> crystals, octahedral slip, {111}<101> was observed. Results similar to the <011> case were found in <001> crystals tested at 980°C/220 MPa.

Observations of Orientation Dependent Creep of Ni3AI

1998 ◽  
Vol 552 ◽  
Author(s):  
Carola Knobloch ◽  
Karin Glock ◽  
Uwe Glatzel
Keyword(s):  
Single Crystals ◽  
Antiphase Boundary ◽  
Constant Load ◽  
Tensile Creep ◽  
Slip Systems ◽  
Transmission Electron ◽  
Secondary Stage ◽  
Anisotropic Elastic ◽  
Stationary Creep ◽  
Habit Planes

ABSTRACTThe influence of crystal orientation on the high temperature creep behavior of Ni3(Al Ti Ta) was investigated by tensile creep testing under a constant load at a temperature of 1123K. The single crystals were oriented close to [001], [011], [111], [557] and [012]. The results show an increasing stationary creep rate from [111] over [011] to [001]. The evolution of the microstructure during creep deformation was studied, using transmission electron microscopy (TEM). Only few systems are active in the primary regime, whereas several slip systems operate in the secondary stage. Habit planes of dislocation pairs separated by an antiphase boundary were examined and compared with anisotropic elastic calculations, explaining the good creep response of [111] oriented single crystals.

Direct Observation of Crystalline Ordering In Naturally Graphitized Carbon Produced by Low Grade Metamorphism

1977 ◽  
Vol 35 ◽  
pp. 162-163
Author(s):  
Thomas R. McKee ◽  
Peter R. Buseck
Keyword(s):  
Crystallite Size ◽  
Sedimentary Rocks ◽  
Carbonaceous Material ◽  
Low Grade ◽  
X Ray ◽  
Graphitized Carbon ◽  
Transmission Electron ◽  
Heat Treated ◽  
Commercial Carbon ◽  
Metamorphic Zone

Sediments commonly contain organic material which appears as refractory carbonaceous material in metamorphosed sedimentary rocks. Grew and others have shown that relative carbon content, crystallite size, X-ray crystallinity and development of well-ordered graphite crystal structure of the carbonaceous material increases with increasing metamorphic grade. The graphitization process is irreversible and appears to be continous from the amorphous to the completely graphitized stage. The most dramatic chemical and crystallographic changes take place within the chlorite metamorphic zone.The detailed X-ray investigation of crystallite size and crystalline ordering is complex and can best be investigated by other means such as high resolution transmission electron microscopy (HRTEM). The natural graphitization series is similar to that for heat-treated commercial carbon blacks, which have been successfully studied by HRTEM (Ban and others).

Precipitation of NiHfsi phase in NiAl single crystals containing Hf

1995 ◽  
Vol 53 ◽  
pp. 532-533
Author(s):  
A. Garg ◽  
R. D. Noebe ◽  
R. Darolia
Keyword(s):  
High Temperature ◽  
Single Crystals ◽  
High Temperature Strength ◽  
Bridgman Technique ◽  
Shell Mold ◽  
Third Phase ◽  
Unknown Phase ◽  
Transmission Electron ◽  
Two Phases ◽  
Nial Matrix

Small additions of Hf to NiAl produce a significant increase in the high-temperature strength of single crystals. Hf has a very limited solubility in NiAl and in the presence of Si, results in a high density of G-phase (Ni16Hf6Si7) cuboidal precipitates and some G-platelets in a NiAl matrix. These precipitates have a F.C.C structure and nucleate on {100}NiAl planes with almost perfect coherency and a cube-on-cube orientation-relationship (O.R.). However, G-phase is metastable and after prolonged aging at high temperature dissolves at the expense of a more stable Heusler (β'-Ni2AlHf) phase. In addition to these two phases, a third phase was shown to be present in a NiAl-0.3at. % Hf alloy, but was not previously identified (Fig. 4 of ref. 2 ). In this work, we report the morphology, crystal-structure, O.R., and stability of this unknown phase, which were determined using conventional and analytical transmission electron microscopy (TEM).Single crystals of NiAl containing 0.5at. % Hf were grown by a Bridgman technique. Chemical analysis indicated that these crystals also contained Si, which was not an intentional alloying addition but was picked up from the shell mold during directional solidification.

The effect of small additions of Cu on precipitation in Al-Mg-Si alloys

1990 ◽  
Vol 48 (2) ◽  
pp. 442-443
Author(s):  
M. Tamizifar ◽  
G. Cliff ◽  
R.W. Devenish ◽  
G.W. Lorimer
Keyword(s):  
Electron Microscopy ◽  
Analytical Electron Microscopy ◽  
Scanning Transmission Electron Microscope ◽  
Argon Atmosphere ◽  
Age Hardening ◽  
X Ray ◽  
Transmission Electron ◽  
Heat Treated ◽  
Analytical Electron ◽  
Scanning Transmission

Small additions of copper, <1 wt%, have a pronounced effect on the ageing response of Al-Mg-Si alloys. The object of the present investigation was to study the effect of additions of copper up to 0.5 wt% on the ageing response of a series of Al-Mg-Si alloys and to use high resolution analytical electron microscopy to determine the composition of the age hardening precipitates.The composition of the alloys investigated is given in Table 1. The alloys were heat treated in an argon atmosphere for 30m, water quenched and immediately aged either at 180°C for 15 h or given a duplex treatment of 180°C for 15 h followed by 350°C for 2 h2. The double-ageing treatment was similar to that carried out by Dumolt et al. Analyses of the precipitation were carried out with a HB 501 Scanning Transmission Electron Microscope. X-ray peak integrals were converted into weight fractions using the ratio technique of Cliff and Lorimer.

Transmission Electron Microscopy study of Bi-based superconducting phases

1990 ◽  
Vol 48 (4) ◽  
pp. 50-51
Author(s):  
J.G. Wen ◽  
K.K. Fung
Keyword(s):  
Electron Microscopy ◽  
Transmission Electron Microscopy ◽  
Single Crystals ◽  
Microscopy Study ◽  
Electron Microscopy Study ◽  
Space Groups ◽  
Superconducting Phases ◽  
Ceramic Samples ◽  
Transmission Electron ◽  
Modulated Structures

Bi-based superconducting phases have been found to be members of a structural series represented by Bi2Sr2Can−1Cun−1On+4, n=1,2,3, and are referred to as 2201, 2212, 2223 phases. All these phases are incommensurate modulated structures. The super space groups are P2/b, NBbmb 2201, 2212 phases respectively. Pb-doped ceramic samples and single crystals and Y-doped single crystals have been studied by transmission electron microscopy.Modulated structures of all Bi-based superconducting phases are in b-c plane, therefore, it is the best way to determine modulated structure and c parameter in diffraction pattern. FIG. 1,2,3 show diffraction patterns of three kinds of modulations in Pb-doped ceramic samples. Energy dispersive X-ray analysis (EDAX) confirms the presence of Pb in the three modulated structures. Parameters c are 3 0.06, 38.29, 30.24Å, ie 2212, 2223, 2212 phases for FIG. 1,2,3 respectively. Their average space groups are all Bbmb.

scholarly journals Ruling Factors in Cinnamaldehyde Hydrogenation: Activity and Selectivity of Pt-Mo Catalysts

Nanomaterials ◽  
2021 ◽  
Vol 11 (2) ◽  
pp. 362
Author(s):  
Marta Stucchi ◽  
Maela Manzoli ◽  
Filippo Bossola ◽  
Alberto Villa ◽  
Laura Prati
Keyword(s):  
Photoelectron Spectroscopy ◽  
Pt Nanoparticles ◽  
Carbon Support ◽  
Catalytic Performance ◽  
Acid Sites ◽  
Hydrogenation Catalysts ◽  
Cinnamaldehyde Hydrogenation ◽  
Transmission Electron ◽  
Heat Treated ◽  
Heating Treatment

To obtain selective hydrogenation catalysts with low noble metal content, two carbon-supported Mo-Pt bimetallic catalysts have been synthesized from two different molybdenum precursors, i.e., Na2MoO4 and (NH4)6Mo7O24. The results obtained by X-ray photoelectron spectroscopy (XPS) and transmission electron microscopy (TEM) combined with the presence and strength of acid sites clarified the different catalytic behavior toward cinnamaldehyde hydrogenation. After impregnating the carbon support with Mo precursors, each sample was used either as is or treated at 400 °C in N2 flow, as support for Pt nanoparticles (NPs). The heating treatment before Pt deposition had a positive effect on the catalytic performance. Indeed, TEM analyses showed very homogeneously dispersed Pt NPs only when they were deposited on the heat-treated Mo/C supports, and XPS analyses revealed an increase in both the exposure and reduction of Pt, which was probably tuned by different MoO3/MoO2 ratios. Moreover, the different acid properties of the catalysts resulted in different selectivity.

Microstructure and Strengthening of Creep-Tested Cryomilled NiAl-AlN

1996 ◽  
Vol 460 ◽  
Author(s):  
Anita Garg ◽  
J. Daniel Whittenberger ◽  
Michael J. Luton
Keyword(s):  
Electron Microscopy ◽  
Transmission Electron Microscopy ◽  
Subgrain Size ◽  
Tensile Creep ◽  
Strain Rates ◽  
Mechanical Grinding ◽  
Intermetallic Matrix ◽  
Transmission Electron ◽  
Intermetallic Matrix Composite ◽  
Nial Powder

ABSTRACTThe mechanical grinding of prealloyed NiAl powder in liquid nitrogen (cryomilling) results in an intermetallic matrix composite where micron sized particle free aluminide cores (grains) are surrounded by thin mantles comprised of nanometer sized A1N particles and NiAl grains. Under high temperature, slow strain rate conditions both compressive and tensile creep testing have shown that the mechanical strength of hot extruded cryomilled NiAl approaches the levels exhibited by advanced NiAl-based single crystals and simple Ni-based superalloys. Transmission electron microscopy of cryomilled materials tested between 1100 and 1300 K revealed little, if any, dislocation structure within the mantle regions, while the NiAl cores contained subgrains and dislocation networks after testing at all strain rates between 10-4 and 10-8 s-1. These and other microstructural observations suggest that creep strength is the result of a fine NiAl grain/subgrain size, the inability of dislocations to move through the mantle and stabilization of the microstracture by the A1N particles.

scholarly journals Characteristics of multiwalled carbon nanotubes-rhenium nanocomposites with varied rhenium mass fractions

2017 ◽  
Vol 7 ◽  
pp. 184798041770717 ◽  
Author(s):  
Anna D Dobrzańska-Danikiewicz ◽  
Weronika Wolany ◽  
Dariusz Łukowiec ◽  
Karolina Jurkiewicz ◽  
Paweł Niedziałkowski
Keyword(s):  
Carbon Nanotubes ◽  
Electron Microscope ◽  
Multiwalled Carbon Nanotubes ◽  
Transmission Electron Microscope ◽  
Scanning Transmission Electron Microscope ◽  
Dark Field ◽  
Multiwalled Carbon ◽  
Weight Percentage ◽  
Transmission Electron ◽  
Scanning Transmission

The purpose of the article is to discuss the process of oxidation of carbon nanotubes subsequently subjected to the process of decoration with rhenium nanoparticles. The influence of functionalization in an oxidizing medium is presented and the results of investigations using Raman spectroscopy and infrared spectroscopy are discussed. Multiwalled carbon nanotubes rhenium-type nanocomposites with the weight percentage of 10%, 20% and 30% of rhenium are also presented in the article. The structural components of such nanocomposites are carbon nanotubes decorated with rhenium nanoparticles. Microscopic examinations under transmission electron microscope and scanning transmission electron microscope using the bright and dark field confirm that nanocomposites containing about 20% of rhenium have the most homogenous structure.

scholarly journals Multi-Scale Investigation of Body-Glaze Interface in Ancient Ceramics

Heritage ◽  
2019 ◽  
Vol 2 (3) ◽  
pp. 2480-2494 ◽  
Author(s):  
Marie Godet ◽  
Gauthier Roisine ◽  
Emmie Beauvoit ◽  
Daniel Caurant ◽  
Odile Majérus ◽  
...  
Keyword(s):  
Single Crystals ◽  
The Body ◽  
Firing Time ◽  
Body System ◽  
Slow Cooling ◽  
French Renaissance ◽  
Electron Microscopies ◽  
Multi Scale ◽  
Continuous Layer ◽  
Transmission Electron

Bernard Palissy is a French Renaissance ceramist renowned for his masterpieces called Rustiques Figulines on which dozens of glazes of different chemistries (and thus firing behaviors) coexist harmoniously. This study aims at gathering information on the master procedure -never revealed- by investigating the body-glaze interface region (focusing on iron-colored honey transparent glaze-white body system). Optical and electron microscopies including transmission electron microscopy (TEM) are used to characterize the micro and nanostructure of both archaeological and replicas interfaces elaborated in controlled conditions (firing time, cooling rate, addition of Al in the glazing mixture). Both types of interfaces are comparable: a modified paste area from which are growing a relatively continuous layer of interfacial crystals identified as lead feldspars (K,Ca)PbAl2Si2O8 micro-sized single-crystals incorporating mullite 3Al2O3.2SiO2 nano-sized single-crystals. Modification of the firing parameters and removal of Al from the glazing mixture change essentially the interface extension and the micro-crystals morphology. By comparing archaeological and replica interfaces and considering previous studies, we can now state that Palissy was very likely adding clay (Al) in his frit. Moreover, he was probably working with a firing time of more than 1 h followed by slow cooling in the oven.

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