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1.
Densities of solid Al and Al-Mg alloys were measured by the dilatometric method for seven compositions at mole fractions of
magnesium: 0.015, 0.05, 0.1, 0.125, 0.15, 0.20, and 0.25. A curvilinear dependence of density on temperature (room temperature
up to 800 K) was observed for all investigated alloys. Results are described by polynomials of the second degree. The molar
volumes of Al-Mg alloys were calculated from the density measurements. It has been found that the densities of solid Al-Mg
alloys show negative deviations from linearity and the molar volumes exhibit positive deviations from ideal behavior for all
samples in the experimental concentration range. The density of the β(Al3Mg2) phase along the (α(Al) + β)/β boundary was calculated and is described by a temperature-dependent polynomial. 相似文献
2.
Densities of solid Al and Al-Li alloys were measured by the dilatometric method for six compositions of mole fractions of
lithium: 0.05,0.1,0.125,0.15,0.20, and 0.25. A curvilinear dependence of density on temperature (room temperature up to 923
K) was observed for all investigated alloys. Results could be described by parabolic equations. The molar volumes of Al-Li
alloys were calculated from the density measurements. It has been found that the densities of solid Al-Li alloys initially
show slightly negative deviations from linearity that reverse to positive above 0.075 mole fraction of Li. Molar volume exhibits
negative deviation from linear dependence for all samples in the experimental concentration range. Power series were used
to fit the dependences of density on temperature and concentration. Coefficients of volume expansion were calculated and discussed.
The density of the β phase along the (α + β)/β boundary was calculated and described by a temperature-dependent polynomial. 相似文献
3.
Densities of solid Mg and Li-Mg alloys were measured for five compositions of mole fractions of Li equal to 0.05,0.1,0.15,0.20,
and 0.25, respectively, by the dilatometric method. The curvilinear dependence of the density on temperature (room temperature
up to 873 K) was observed for all investigated alloys. Results could be described by parabolic equations. The molar volumes
of Li-Mg alloys were calculated from the density measurements. It has been found that the densities of solid Li-Mg alloys
show positive deviations from linearity, and the molar volumes exhibit negative deviations from linear dependence for all
samples in the experimental concentration range. It was possible to describe the dependence of density on temperature and
concentration by a polynomial. Coefficients of thermal expansion were calculated and discussed. The density of the (Li) phase
along the (Li)/[(Mg) + (Li)] boundary was calculated and described by a temperature-dependent polynomial of the third power. 相似文献
4.
Through the application of the maximum bubble pressure and dilatometric method, density and surface tension were investigated.
The experiments were conducted in the temperature range from 583 K≤T≤1257 K. The surface tension was measured for pure antimony
and for six liquid Sb-Sn alloys (mole fractions X
Sn=0.2, 0.4, 0.6, 0.8, 0.9, and 0.935 mm2) and measurements of the density were only for alloys. It has been observed that both surface tension and density show linear
dependence on temperature. The temperature-concentration relation of both surface tension and density were determined with
minimization procedures. The surface tension isotherms calculated at 873 K and 1273 K show slight negative deviations from
linearity changes, but the observed maximal differences did not exceed 30 mN · m−1. The surface tension calculated from Butler’s model was higher than the experimental value for most concentrations and also
showed curvilinear temperature dependence. The experimental densities and the molar volumes of the Sb-Sn liquid alloys conform
very closely to ideal behavior with differences comparable to the experimental errors. 相似文献
5.
Through the application of the maximum bubble pressure and dilatometric method, density and surface tension were investigated.
The experiments were conducted in the temperature range from 583 K≤T≤1257 K. The surface tension was measured for pure antimony
and for six liquid Sb-Sn alloys (mole fractions X
Sn=0.2, 0.4, 0.6, 0.8, 0.9, and 0.935 mm2) and measurements of the density were only for alloys. It has been observed that both surface tension and density show linear
dependence on temperature. The temperature-concentration relation of both surface tension and density were determined with
minimization procedures. The surface tension isotherms calculated at 873 K and 1273 K show slight negative deviations from
linearity changes, but the observed maximal differences did not exceed 30 mN · m−1. The surface tension calculated from Butler’s model was higher than the experimental value for most concentrations and also
showed curvilinear temperature dependence. The experimental densities and the molar volumes of the Sb-Sn liquid alloys conform
very closely to ideal behavior with differences comparable to the experimental errors. 相似文献
6.
J. Colin C. Gonzalez R. Herrera J. A. Juarez-Islas 《Journal of Materials Engineering and Performance》2002,11(5):487-491
This study carried out a characterization of chill-cast NiAl alloys with copper additions, which were added to NiAl, such
that the resulting alloy composition occurred in the β-field of the ternary NiAlCu phase diagram. The alloys were vacuum induction
melted and casted in copper chill molds to produce ingots 0.002 m thick, 0.020 m wide, and 0.050 m long. X-ray diffractometry
(XRD) and transmission electron microscopy (TEM) performed in chill-cast ingots identified mainly the presence of the β-(Ni,Cu)Al
phase. As-cast ingots showed essentially no ductility at room temperature except for the Ni50Al40Cu10 alloy, which showed 1.79% of elongation at room temperature. Ingots with this alloy composition were then heat treated under
a high-purity argon atmosphere at 550 °C (24 h) and cooled either in the furnace or in air, until room temperature was reached.
β-(Ni,Cu)Al and γ′(Ni,Cu)3Al were present in specimens cooled in the furnace and β-(Ni,Cu)Al, γ′(Ni,Cu)3Al plus martensite-(Ni,Cu)Al were present in specimens cooled in air. Thermogravimetric analysis indicated that martensite
transformation was the result of a solid-state reaction with M
s ∼ 470 and M
f ∼ 430 °C. Tensile tests performed on bulk heat-treated ingots showed room-temperature ductility between 3 and 6%, depending
on the cooling media. 相似文献
7.
The superplastic deformation behavior of Ti3Al based(α
2+β alloy was studied with respect to the volume fraction of α2/β. Three alloys containing 21, 50 and 77% in volume fractions ofβ exhibited large tensile elongations of over 500% at 970°C with a strain rate of 2.5x10-4 sec-1. The largest elongation was observed in the alloy with 21% ofβ. As the volume fraction ofβ phase increased, the flow stress and correspondingly, the strain-rate sensitivity values decreased. Due to the higher diffusivity
of Ti in,β phase than in α2 phase, the increase inβ volume fraction from 21 % to 77% accelerated the dynamic grain growth, and degraded the superplasticity of the Ti3Al-based alloys. The strain-based grain growth behavior was quantitatively analyzed and incorporated into a constitutive equation.
The calculated flow curves are in agreement with the experimental ones in the stable deformation region. 相似文献
8.
W. Gasior J. Pstru Z. Moser A. Krzyak K. Fitzner 《Journal of Phase Equilibria and Diffusion》2003,24(1):40-49
With the maximum bubble pressure method, the density and surface tension were measured for five Ag-Bi liquid alloys (X
Bi=0.05, 0.15, 0.25, 0.5, and 0.75), as well as for pure silver. The experiments were performed in the temperature range 544–1443
K. Linear dependences of both density and surface tension versus temperature were observed, and therefore the experimental
data were described by linear equations. The density dependence on concentration and temperature was derived using the polynomial
method. A similar dependence of surface tension on temperature and concentration is presented. Next, the Gibbs energy of formation
of solid Bi2O3, as well as activities of Bi in liquid Ag-Bi alloys, were determined by a solid-state electromotive force (emf) technique
using the following galvanic cells: Ni, NiO, Pt/O
−2/W, Ag
X
Bi
(1−X), Bi
2
O
3(s). The Gibbs energy of formation of solid Bi2O3 from pure elements was derived:
=−598 148 + 309.27T [J · mol−1] and
=−548 008 + 258.94T [J · mol−1]; the temperature and the heat of the α → δ transformation for this solid oxide were calculated as 996 K and 50.14 J · mol−1. Activities of Bi in the liquid alloys were determined in the temperature range from 860–1075 K, for five Ag-Bi alloys (X
Ag=0.2, 0.35, 0.5, 0.65, 0.8), and a Redlich-Kister polynomial expansion was used to describe the thermodynamic properties of
the liquid phase. Using Thermo-Calc software, the Ag-Bi phase diagram was calculated. Finally, thermodynamic data were used
to predict surface tension behavior in the Ag-Bi binary system. 相似文献
9.
With the maximum bubble pressure method, the density and surface tension were measured for five Ag-Bi liquid alloys (X
Bi=0.05, 0.15, 0.25, 0.5, and 0.75), as well as for pure silver. The experiments were performed in the temperature range 544–1443
K. Linear dependences of both density and surface tension versus temperature were observed, and therefore the experimental
data were described by linear equations. The density dependence on concentration and temperature was derived using the polynomial
method. A similar dependence of surface tension on temperature and concentration is presented. Next, the Gibbs energy of formation
of solid Bi2O3, as well as activities of Bi in liquid Ag-Bi alloys, were determined by a solid-state electromotive force (emf) technique
using the following galvanic cells: Ni, NiO, Pt/O
−2/W, Ag
X
Bi
(1−X), Bi
2
O
3(s). The Gibbs energy of formation of solid Bi2O3 from pure elements was derived: =−598 148 + 309.27T [J · mol−1] and =−548 008 + 258.94T [J · mol−1]; the temperature and the heat of the α → δ transformation for this solid oxide were calculated as 996 K and 50.14 J · mol−1. Activities of Bi in the liquid alloys were determined in the temperature range from 860–1075 K, for five Ag-Bi alloys (X
Ag=0.2, 0.35, 0.5, 0.65, 0.8), and a Redlich-Kister polynomial expansion was used to describe the thermodynamic properties of
the liquid phase. Using Thermo-Calc software, the Ag-Bi phase diagram was calculated. Finally, thermodynamic data were used
to predict surface tension behavior in the Ag-Bi binary system. 相似文献
10.
11.
Based on an assessment of the available experimental thermochemical and phase diagram information available, the phase equilibria
of the C-Hf-Zr system were calculated. The G of the individual phases was described with thermodynamic models. The liquid phase was described as a substitutional solution
using the Redlich-Kister formalism for excess G. Graphite was treated as a stoichiometric phase. The solid solutions of carbon in α(Hf,Zr) and β(Hf,Zr), as well as the non-stoichiometric
phase (Hf,Zr)C1−x, were represented as interstitial solid solutions using the compound energy model with two sublattices. The parameters in
the models were determined by computerized optimization using selected experimental data. A detailed comparison was made between
calculation and experimental data. 相似文献
12.
V. M. Imayev R. M. Imayev T. G. Khismatullin 《The Physics of Metals and Metallography》2008,105(5):484-490
A new approach to obtaining fine-grained structure in intermetallic-compound alloys such as γ-TiAl + α2-Ti3Al has been suggested. This approach is based on the use of alloys that solidify as the β phase, which contain β-stabilizing additives such as Nb and Mo and are characterized by the small size of crystallites already in the cast state; in these alloys, a simple heat treatment makes it possible to substantially decrease the fraction of the lamellar component and to increase the content of the β(B2) phase. It is shown on the example of the Ti-43Al-7(Nb,Mo)-0.2B (at %) alloy that this heat treatment ensures superplastic properties in the material in the temperature range of T = 1050–1130°C at a deformation rate $ \dot \varepsilon A new approach to obtaining fine-grained structure in intermetallic-compound alloys such as γ-TiAl + α2-Ti3Al has been suggested. This approach is based on the use of alloys that solidify as the β phase, which contain β-stabilizing
additives such as Nb and Mo and are characterized by the small size of crystallites already in the cast state; in these alloys,
a simple heat treatment makes it possible to substantially decrease the fraction of the lamellar component and to increase
the content of the β(B2) phase. It is shown on the example of the Ti-43Al-7(Nb,Mo)-0.2B (at %) alloy that this heat treatment ensures superplastic
properties in the material in the temperature range of T = 1050–1130°C at a deformation rate = 1.7 × 10−4 K−1. Under these temperature-strain-rate conditions, relative elongations such as δ = 160–230% and low flow stresses such as
σ = 36–100 MPa characteristic of superplastic flow have been obtained. It has been shown for the first time for the intermetallic
γ-TiAl + ga2-Ti3Al alloy that a sheet semifinished product cut out from an ingot subjected only to heat treatment can have plasticity acceptable
for press forming.
Original Russian Text ? V.M. Imayev, R.M. Imayev, T.G. Khismatullin, 2008, published in Fizika Metallov i Metallovedenie,
2008, Vol. 105, No. 5, pp. 516–522.
The author is also known by the name Imayev. The name used here is a transliteration under the BSI/ANSI scheme adopted by
this journal.—Ed. 相似文献
13.
Infrared-brazing Fe3Al with Au–44Cu as filler metal has been investigated. The brazed joint consists mainly of a β-phase, Au8 − x
Cu4 + x
Al4, caused by the dissolution of Al from Fe3Al substrate into the braze alloy. The depletion of Al from Fe3Al substrate results in the formation of a layer of β-phase particles dispersed in the Fe-rich phase. The highest shear strength
for AuCu filler is 327 MPa for specimens infrared brazed at 880°C for 180 s. The brazed joint is mainly fractured along the
central β-phase in which the fractograph exhibits quasi-cleavage with dimples. Increasing the brazing time or temperature
will deteriorate the bonding strength of the joint, and the fracture mode is prone to cleavage of brittle fracture. Au–44Cu
filler demonstrates a great potential for bonding Fe3Al intermetallic compound. 相似文献
14.
Katsunari Oikawa Takuya Ota Yousuke Imano Toshiro Omori Ryosuke Kainuma Kiyohito Ishida 《Journal of Phase Equilibria and Diffusion》2006,27(1):75-82
Phase equilibria and martensitic and magnetic phase transformations of the β phase in the Co−Ni−Ga system have been investigated.
It has been shown that the β phase is in equilibrium with the α-phase over a wide range compositions at 600–1100°C. The β
phase exhibits both a paramagnetic-ferromagnetic transition and a thermoelastic martensitic transition from B2 to L10 structure. The Curie temperature T
C
increases with decreases with decreasing Ni content and with increasing Ga content. The composition region of the β phase
exhibiting the thermoelatstic martensitic transformation from ferromagnetic austenite is located near the α+β two-phase region.
T
C
and M
s
of α+β two-phase alloys increase with increasing annealing temperature.
This paper was presented at the International Symposium on User Aspects of Phase Diagrams, Materials Solutions Conference
and Exposition. Columbus, Ohio, 18–20 October, 2004. 相似文献
15.
16.
Effect of Zr addition on microstructures and mechanical properties of Ni-46Ti-4Al alloy 总被引:1,自引:0,他引:1
The microstructures and mechanical properties of Ni-(46-x)Ti-4Al-xZr (x = 0-8, at.%) alloys have been investigated by scanning electron microscopy (SEM), transmission electron microscopy (TEM), and mechanical tests. The results show that the Ni-Ti-Al-Zr alloys are composed of TiNi and (Ti, Al) 2 Ni with Zr as a solid solution element in both phases, and the third phase, (Zr, Ti, Al) 2 Ni, appears in Ni-40Ti-4Al-6Zr and Ni-38Ti-4Al-8Zr alloys. The compressive yield strength at room temperature increases with the increase of Zr content due to the solid-solution strengthening of Zr and precipitation strengthening of (Ti, Al, Zr) 2 Ni phase. However, the Ni-42Ti-4Al-4Zr alloy exhibits the maximum compressive yield strength at 873 and 973 K because of the softening of (Zr, Ti, Al) 2 Ni phase in the alloys with more Zr addition. The tensile stress-strain tests and the SEM fracture surface observations show that the brittle to ductile transition temperature of Ni-42Ti-4Al-4Zr alloy is between 873 and 923 K. 相似文献
17.
B. B. Straumal A. S. Gornakova Y. O. Kucheev B. Baretzky A. N. Nekrasov 《Journal of Materials Engineering and Performance》2012,21(5):721-724
Zr-Nb alloys play the important role in the energy production being the main material for the cladding of nuclear fuel in
the nuclear power plants. The thermo-mechanical treatment of these alloys proceeds in the (αZr) + (βZr, Nb) two-phase area
of the Zr-Nb phase diagram. Therefore, the morphology and the mutual arrangement of the (Zr) and (Nb) phases play an extremely
important role. The microstructure of binary Zr-Nb alloys with 2.5, 4, and 8 wt.% Nb after long anneals (720 h) was studied
between 660 and 810 °C in the two-phase (αZr) + (βZr, Nb) area of the Zr-Nb phase diagram. (βZr, Nb)/(βZr, Nb) grain boundaries
(GBs) completely or incompletely wetted by the αZr phase were observed. The portion of the completely wetted (βZr, Nb)/(βZr,
Nb) GBs increases from 10% (at 660 °C) to 60% close to the upper border of the (αZr) + (βZr, Nb) two-phase area of the Zr-Nb
phase diagram (850 °C). The temperature of the beginning of the GB wetting phase transition of (βZr, Nb)/(βZr, Nb) GBs by
the αZr phase is T
ws = 630 ± 10 °C. The αZr/αZr GBs completely wetted by a layer of (βZr, Nb) phase were not observed in the studied samples. 相似文献
18.
《Intermetallics》2016
First-principles calculations have been performed to investigate the phase stability, elastic, and thermodynamic properties of Co3(Al,Mo,Nb) with the L12 structure. Calculated elastic constants show that Co3(Al,Mo,Nb) is mechanically stable and possesses intrinsic ductility. It is found that the shear and Young's moduli of Co3(Al,Mo,Nb) are smaller than those of Co3(Al,W). Calculated density of states indicate the existence of covalent-like bonding in Co3(Al,Mo,Nb). Temperature-dependent thermodynamic properties of Co3(Al,Mo,Nb) can be described satisfactorily using the Debye-Grüneisen approach, including entropy, enthalpy, heat capacity and linear thermal expansion coefficient, showing their significant temperature dependences. Furthermore the obtained data can be employed in the modeling of thermodynamic and mechanical properties of Co-based alloys to enable the design of high temperature alloys. 相似文献
19.
G. Ghosh 《Journal of Phase Equilibria and Diffusion》2002,23(4):310-328
A synergistic approach of thermodynamic and kinetic modeling is applied to the Cr-Ti-V system. To assist the design of (α+β)
and β titanium alloys for structural applications and vanadium alloys for fusion reactor applications, a set of self-consistent
and optimized thermodynamic model parameters is presented to describe the phase equilibria of the Cr-Ti, Cr-V, Ti-V, and Cr-Ti-V
systems. The Laves phases, α-Cr2Ti, β-Cr2Ti, and γ-Cr2Ti, are described by a two-sublattice model assuming antistructure atoms on both sublattices. The calculated thermodynamic
quantities and phase diagrams are in good accord with the corresponding experimental data. To assist the simulation of the
kinetics of diffusional transformations in bodycentered cubic (bcc) alloys, the atomic mobilities of Cr, Ti, and V are modeled.
A set of optimized mobility parameters is given. Very good agreement between the calculated and experimental diffusivities
was found. 相似文献
20.
G. Ghosh 《Journal of Phase Equilibria》2002,23(4):310-328
A synergistic approach of thermodynamic and kinetic modeling is applied to the Cr-Ti-V system. To assist the design of (α+β) and β titanium alloys for structural applications and vanadium alloys for fusion reactor applications, a set of self-consistent and optimized thermodynamic model parameters is presented to describe the phase equilibria of the Cr-Ti, Cr-V, Ti-V, and Cr-Ti-V systems. The Laves phases, α-Cr2Ti, β-Cr2Ti, and γ-Cr2Ti, are described by a two-sublattice model assuming antistructure atoms on both sublattices. The calculated thermodynamic quantities and phase diagrams are in good accord with the corresponding experimental data. To assist the simulation of the kinetics of diffusional transformations in bodycentered cubic (bcc) alloys, the atomic mobilities of Cr, Ti, and V are modeled. A set of optimized mobility parameters is given. Very good agreement between the calculated and experimental diffusivities was found. 相似文献