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1.
The ultrasound velocity in GdCl3 + MCl (M = Na, Cs) chloride melts is measured over wide temperature and composition ranges, and their adiabatic compressibility is
calculated. A correlation is established between the relative deviations of these properties from their values in hypothetic
ideal salt mixtures and the reciprocal alkali-metal cation radii. The role of lanthanide compression in the propagation of
sound vibrations in the chlorides of cerium group REMs is revealed. 相似文献
2.
V. I. Minchenko V. A. Khokhlov V. P. Stepanov I. V. Korzun 《Russian Metallurgy (Metally)》2010,(8):702-706
The ultrasound velocity in binary LaCl3 + MCl (M = Li, Na, K, Rb, and Cs) melts is measured, and their adiabatic compressibility is calculated as a function of temperature
and composition. A relation is established between the relative deviations of these properties from their values for hypothetic
ideal salt mixtures, on the one hand, and the ionic potentials of the alkali-metal cations, on the other. 相似文献
3.
G. G. Mikhailov L. A. Makrovets L. A. Smirnov L. E. Dresvyankina 《Russian Metallurgy (Metally)》2016,2016(6):522-529
Analysis of the ternary phase diagrams of Ce2O3- and CeO2-containing oxide systems allowed us to find the oxide compounds that form during steel deoxidizing with cerium and with cerium together with aluminum, calcium, magnesium, or silicon. The temperature dependences of the equilibrium constants of formation of Ce2O3 oxides and Ce2O3 · Al2O3, Ce2O3 · 11Al2O3, Ce2O3 · 2SiO2, 7Ce2O3 · 9SiO2 and Ce2O3 · SiO2 compounds are found. Surfaces for the component solubility in metallic melts Fe–Al–Ce–O–C, Fe- Ca–Ce–O–C, Fe–Mg–Ce–O–C, and Fe–Si–Ce–O–C are constructed. Nonmetallic inclusions that form in the course of experimental melts of St20 steel after its deoxidizing with silicocalcium and rare-earth metal (REM)-containing master alloys in a ladle furnace after degassing are studied. Phase inhomogeneity of the inclusions is found. As a rule, they consist of phases classified into the following three groups: oxide–sulfide, sulfide–oxide, and multiphase oxide–sulfide melt. Calcium aluminates are found to be components of complex sulfide-oxide noncorrosive inclusions. 相似文献
4.
S. K. Thakur B. K. Dhindaw N. Hort K. U. Kainer 《Metallurgical and Materials Transactions A》2004,35(13):1167-1176
Magnesium alloy-based hybrid composites with carbon-fiber, SiC
p
, and in-situ Mg2Si reinforcements have been prepared by the squeeze-infiltration technique. The results of the studies done on the measurement
of the coefficient of thermal expansion after thermal cycling of these composites show that the thermal cycling initially
leads to rapid linear expansion of the composite. However, the expansion becomes stabilized after a few cycles, pointing toward
formation of the stable interfaces due to the formation of stable precipitates. The model for the growth kinetics of these
precipitates at the interface shows a rapid initial growth of the precipitates with the number of thermal cycles, which becomes
staturated after a few thermal cycles. The thermal treatment of the composite lowers the coefficient of linear thermal expansion,
which can be explained on the basis of further stabilization of the interfaces after the thermal treatment. 相似文献
5.
A. A. Yaroslavtsev A. P. Menushenkov R. V. Chernikov E. S. Clementyev V. N. Lazukov Ya. V. Zubavichus A. A. Veligzhanin N. N. Efremova A. G. Kuchin A. V. Gribanov 《Russian Metallurgy (Metally)》2011,(7):640-645
The effective valence of cerium is studied by L
3-XANES spectroscopy using synchrotron radiation in the following valence-unstable systems with different types of magnetic
ordering: a CeNi matrix doped with neodymium, praseodymium, and gadolinium ions in the temperature range 5–300 K and the Ce2Fe17 − x
Mn
x
intermetallic compound. The obtained dependences are discussed in terms of generally accepted models of states with an intermediate
valence of rare-earth ions. Possible correlations between the effective valence of cerium and the magnetic properties of the
substances are taken into account. 相似文献
6.
The high-temperature corrosion of a 12Kh18N10T steel in the melt of lithium and potassium chlorides and neodymium trichlorides is investigated at a temperature of 773 K. The NdCl3 concentration is varied from 0.2 to 5 mol %. In this study, neodymium is an analog of uranium. The composition of the electrolyte is close to the composition of the electrolytes used for processing nitride spent nuclear fuel (SNF). The main investigation technique is gravimetry, which includes aging of the steel in the melt for 1–24 h. Atomic absorption and electron microprobe analyses are also used. 相似文献
7.
A. V. Volkovich M. V. Solodkova Zh. V. Zhukova M. V. Sigailov D. P. Vent 《Russian Metallurgy (Metally)》2011,(2):122-126
The kinetics of dissolution and the solubility of strontium oxide in melts of KCl, NaCl, CsCl, (3Li-2K)Cleut (eutectic), and LiCl containing 5, 7, and 12 mol % SrCl2 at 973–1073 K are determined by the isothermal saturation method. The diffusion coefficients of strontium ions in these salt
systems are estimated. 相似文献
8.
Duygu Ağaoğulları Özge Balcı İsmaİl Duman M. Lütfİ Öveçoğlu 《Metallurgical and Materials Transactions B》2011,42(3):568-574
The α-rhombohedral and β-rhombohedral crystal structures of pure elemental boron powders have been synthesized via gas phase thermal dissociation
of BCl3 by H2 on a quartz substrate. The parameters affecting the crystal structures of the final products and the process efficiency,
such as BCl3/H2 molar ratio (1/2 and 1/4) and reaction temperature (1173 K to 1373 K [900 °C to 1100 °C]), have been examined. The experimental
apparatus of original design has enabled boron powders to be obtained at temperatures lower than those in the literature.
The surface/powder separation problem encountered previously with different substrate materials has been avoided. Boron powders
have been synthesized with a minimum purity of 99.99 pct after repeated HF leaching. The qualitative analysis of exhaust gases
has been conducted using a Fourier transform infrared spectroscope (FTIR). The synthesized powders have been characterized
using an X-ray powder diffractometer (XRD) and scanning electron microscope (SEM) techniques. The results of the reactions
have been compared with equilibrium predictions performed using the FactSage 6.2 (Center for Research in Computational Thermochemistry,
Montreal, Canada) thermochemical software. 相似文献
9.
A software package is developed to predict the types of crystal structures for ternary ABX
2 (A, B are metals; X = Fe, Co, Ni) intermetallics under normal conditions. These compounds are shown to be characterized by a Heusler-phase-type
cubic structure. New ABFe2 Heusler phases are predicted for the first time. 相似文献
10.
Dinabandhu Ghosh 《Metallurgical and Materials Transactions B》2010,41(6):1274-1283
In the literature, no direct derivation exists of the quadratic activity coefficient vs composition relationships for a quaternary system with high solute concentrations. Such relations for a ternary system (1-2-3)
were derived by Darken by extending the results of a binary system (1-2), introducing a new concept of “hypothetical system”
(2-3). To present a better scheme to find the activity coefficient-composition relations for multicomponent systems, derivations
are made for a quaternary system A-B-C-D in the current work. Using a MacLaurin series expansion, the (Raoultian) activity coefficient, ln γ
i
, of each component is equated with a quadratic expression of mole fractions (x), involving the activity coefficient at zero concentration ( gi0 ) \left( {\gamma_{i}^{0} } \right) and nine interaction coefficients (ε). Subsequently, with the help of a Gibbs–Duhem equation, followed by a comparison of coefficients, most preceding 9 × 4,
i.e., 36 interaction coefficients are eliminated, leaving behind only three self- and three ternary interaction coefficients,
which are enough to express the activity coefficient vs composition relationships for the solutes B, C, and D, as well as for the solvent A. Setting the mole fraction x
D
= 0, the preceding expressions establish the same relations as proposed by Darken for the ternary system A-B-C. The derivation also clarifies how the quadratic concentration terms accompany the first-order interaction coefficients,
not the second-order ones. Applications of the derived relations to determine simultaneously the activity coefficients gi0 \gamma_{i}^{0} and the interaction coefficients ε in a new way in some iron- and steelmaking systems are presented. A new data on interaction coefficients in liquid iron at
1873 K (1600 °C),
e\textV\textV = - 6. 1, \varepsilon_{\text{V}}^{\text{V}} = - 6. 1, has been generated through such an application. 相似文献
11.
Chung-Sik Yoo Sung K. Lim C. S. Yoon C. K. Kim 《Metallurgical and Materials Transactions A》2004,35(7):2057-2061
Alloys of Co78-x
Pt
x
B10Si12 were produced using the melt-spin process in order to study the crystallization behavior and ensuing magnetic properties
of the Co-Pt amorphous alloys as a function of the Pt content. We showed that when x>15, well below its stoichiometric composition, CoPt intermetallic compound crystallized in the amorphous alloy. Below this
composition, the main crystallization product was Co with Pt dissolved in its lattice. The nucleation of CoPt greatly altered
the crystallized microstructures and magnetic properties of the Co-Pt amorphous alloys during annealing. In spite of the nucleation
of CoPt with its high magnetic anisotropy, the highest coercivity was obtained when x was 15, free of the CoPt grains. It was also concluded that the Pt addition, in general, triggered crystallization to occur
at a progressively lower temperature. 相似文献
12.
The stability of the reactive interface during the solid-state displacement reaction, Cu2O+Co1−X
Fe
X
=2Cu+(Co1−X
Fe
X
)O, is studied as a function of Co-Fe alloy composition at 1223 K. For X≤0.03, the reaction zone has a layered structure, and the cation diffusion in (Co, Fe)O is the rate-limiting step. The interface
is unstable in the early stages of the reaction; the instability decreases with time as the oxide thickness increases, and
the interface becomes planar at long times. The time required for the attainment of interface planarity increases with the
value of X. The reaction kinetics are consistent with the available cation-diffusion data in (Co, Fe)O. For X≥0.045, the product zone is a composite of Cu+(Co, Fe)O, and the rate is limited by the oxygen transport in copper. The transition
to interface instability occurs when the oxide can support a cation flux that exceeds the maximum possible oxygen flux in
copper. During the reaction, composition gradients develop in (Co, Fe)O because of higher diffusion rates for iron than for
cobalt. 相似文献
13.
Youming Liu Wenyi Li Xun Cai Liuhe Li Qiulong Chen Bofan Xu 《Metallurgical and Materials Transactions A》2004,35(8):2511-2515
Rare earth CeO2 was investigated as an additive for in-situ preparation of TiC/Al composites using XD (exothermal dispersion) + casting technology. Experiment results showed that an
optimum CeO2 addition of 0.5 wt pct promotes the generation and refinement of TiC particles, prevents the formation of Al3Ti, increases the wettability between the TiC ceramic particles and the Al matrix, and improves the mechanical properties
of composite. A corresponding thermodynamic model was proposed for the mechanism. 相似文献
14.
Shigenari Hayashi Wen Wang Daniel J. Sordelet Brian Gleeson 《Metallurgical and Materials Transactions A》2005,36(7):1769-1775
The effect of platinum addition on the interdiffusion behavior of γ-Ni + γ′-Ni3Al alloys was studied by using diffusion couples comprised of a Ni-Al-Pt alloy mated to a Ni-Al, Ni-Al-Cr, or Ni-based commercial
alloy. The commercial alloys studied were CMSX-4 and CMSX-10. Diffusion annealing was at 1150 °C for up to 100 hours. An Al-enriched
γ′-layer often formed in the interdiffusion zone of a given couple during diffusion annealing due to the uphill diffusion of
Al. This uphill diffusion was ascribed to Pt addition decreasing the chemical activity of aluminum in the γ + γ′ alloys. For a given diffusion couple end member, the thickening kinetics of the γ′ layer that formed increased with increasing Pt content in the Ni-Al-Pt γ + γ′ alloy. The γ′-layer thickening kinetics in diffusion couples with Cr showed less of a dependence on Pt concentration. Inference of a negative
effect of Pt and positive effect of Cr on the Al diffusion in this system enabled explanation of the observed interdiffusion
behaviors. There was no or minimal formation of detrimental topologically close-packed (TCP) phases in the interdiffusion
zone of the couples with CMSX-4 or CMSX-10. An overlay Pt-modified γ + γ′ coating on CMSX-4 showed excellent oxidation resistance when exposed to air for 1000 hours at 1150 °C. Moreover, the Al
content in the coating was maintained at a relatively high level due to Al replenishment from the CMSX-4 substrate. 相似文献
15.
16.
Ryosuke O. Suzuki Katsutoshi Ono Koh Teranuma 《Metallurgical and Materials Transactions B》2003,34(3):287-295
A concept for calciothermic direct reduction of titanium dioxide in molten CaCl2 is proposed and experimentally tested. This production process consists of a single cell, where both the thermochemical reaction
of the calciothermic reduction and the electrochemical reaction for recovery of the reducing agent, Ca, coexist in the same
molten CaCl2 bath. A few molar percentages of Ca dissolve in the melt, which gives the media a strong reducing power. Using a carbon anode
and a Ti basket-type cathode in which anatase-type TiO2 powder was filled, a metallic titanium sponge containing 2000 ppm oxygen was produced after 10.8 ks at 1173 K in the CaCl2 bath. The optimum concentration of CaO in the molten CaCl2 was 0.5 to 1 mol pct, to shorten the operating time and to achieve a lower oxygen content in Ti. 相似文献
17.
N. D. Alexopoulos S. G. Pantelakis 《Metallurgical and Materials Transactions A》2004,35(10):3079-3089
The mechanical performance of A357 cast ingot aluminum alloy specimens subjected to 25 different artificial aging heat treatments
has been experimentally investigated. For the quality evaluation of the artificially aged alloys, the quality index Q
D
, proposed by the authors, has been involved. The index Q
D
interprets quality as the potential of an alloy to offer combinations of tensile strength, ductility, and toughness at certain
levels of values. The evaluation of the alloy quality using Q
D
relies on the availability of the materials tensile flow curve. To facilitate the exploitation of Q
D
for quality assessment, approximations of Q
D
are developed. In the proposed approximations, Q
D
is formulated as a function of ultimate tensile strength, yield strength, and elongation to fracture, or alternatively, as
a function of Rockwell hardness E and Charpy impact energy values. Accurate estimations of the quality index Q
D
are compared against Q
D
values obtained by using the proposed approximations. 相似文献
18.
In this work, a reactive synthesis process is proposed to obtain ZrAl3-Al2O3 particulate-reinforced aluminum matrix composites. The process involves the in-situ formation of Al2O3 and ZrAl3 from Al-ZrO2 green compacts. Upon compact heating, it is found that reduction of ZrO2 by molten aluminum occurs at temperatures above 750 °C, leading to the development of ZrAl3 and Al2O3 phases. Thermodynamically, it is found that the reduction of zirconium oxide is driven mainly by the dissolution of Zr in
molten aluminum. Because the solubility of Zr in liquid aluminum is extremely small, the formation of ZrAl3 is favored after relatively small Zr dissolutions. The first Zr-Al intermetallics to form at the lowest temperatures seem
to be metastable, as infered from the measured atom ratios for Al : Zr of 2.83 : 1. At increasing temperatures, the reaction
comes into completion, resulting in the formation of equilibrium intermetallic ZrAl3 phases. The results obtained from differential scanning calorimetry (DSC) indicate that by increasing the scanning rates,
both the reaction temperature and the exothermic peak intensity also increase. Alternatively, it is found that by reducing
the amount of ZrO2 in the green compact, the in-situ reaction temperatures also shift toward higher values. 相似文献
19.
Tatsuya Fukino Sadahiro Tsurekawa Yasuhiro Morizono 《Metallurgical and Materials Transactions A》2011,42(3):587-593
This article presents in-situ observation of ferrite (α)/austenite (γ) phase transformation in an Fe-8.5 at. pct Ni alloy deformed by rolling using an automated scanning electron microscopy/energy
backscattered diffraction (SEM/EBSD) system. During heating, recrystallization in α phase and α → γ phase transformation independently occurred. The γ grains nucleated in unrecrystallized α grains were most probably incorporated into the grain interior of recrystallized α grains. They did not have any specific orientation relation (OR) with recrystallized α grains and grew in an isotropic manner. On the other hand, the intragranular γ grains nucleated in recrystallized α grains had a Kurdjumov–Sachs (K-S) OR with the α grains and grew in a considerably anisotropic manner. They preferentially grew along the common direction of surface traces
of {110}
α
/{111}
γ
. Approximately half of grain boundary (GB) allotriomorphs had either the K-S OR or the Nishiyama–Wasserman (N-W) OR with
the parent α grains. The γ allotriomorphs predominantly grew into the α grain having the special OR with themselves. The GB character distribution of γ phase at high temperatures was measured. The fraction of CSL boundaries was as high as 63 pct, particularly that of Σ3 grain
boundaries (GBs) was 54 pct. 相似文献
20.
G. Sreenivasulu N. K. Mukhopadhyay G. V. S. Sastry A. K. Singh 《Metallurgical and Materials Transactions A》2005,36(10):2601-2613
The stability of a lamellar structure consisting of α
2 and γ phases in alloys Ti-48Al, Ti-48Al-2Mo, Ti-48Al-4Nb, and Ti-48Al-1Mo-4Nb has been studied as a function of aging time and
temperature. The alloys were solution treated (1400 °C, 30 min, and air-cooled (AC)) and aged at 1000 °C and 1100 °C for 1,
4, and 16 hours, respectively. The results indicate that the kinetics of lamellae to equiaxed transformation depends on alloy
chemistry, aging time, and temperature. The Nb decreases and Mo increases the kinetics of transformation. The combined effect
of Nb and Mo results in the highest volume fraction of equiaxed microstructure at a given aging time and temperature. The
results have been discussed in relation to microstructural features and have been compared with those reported in other α
2+γ alloys. 相似文献