共查询到20条相似文献,搜索用时 10 毫秒
1.
2.
Phase diagrams of Fe-Ni-Cr are calculated as a function of temperature from the liquid phase down to 500 K using thermodynamic
values of the pertinent phases. These phases are the liquid, fcc, bcc, sigma, and γ′-FeNi3 phases. Not only the thermodynamic values calculated from the models for the various phases are in agreement with experimental
data available in the literature, the calculated phase diagrams are also in agreement with experimental data over a wide range
of temperature. Below 1123 K, no conventional phase diagram data are available in the literature due to kinetic difficulties.
However, the calculated diagram is able to explain the results obtained when the alloys are subjected to electron irradiation.
Deceased, was with the Department of Metallurgical and Mineral Engineering, University of Wisconsin. 相似文献
3.
K. F. Michaels W. F. Lange J. R. Bradley H. I. Aaronson 《Metallurgical and Materials Transactions A》1975,6(10):1843-1848
The Kaufman approach to phase equilibria involving primarily the fcc, bcc and hcp phases was examined outside the Group Nos. 4 to 10 range where it is customarily employed. The “stability parameters” (ΔH and ΔS of transformation) for most elements in the Group Nos. 1 to 3 region were found to fit satisfactorily the correlation curves of stability parametervs group no.; some of the parameters for Al, Be, Mg and Ti, however, did not. The rare earth parameters fit well in the Group No. 3.5 position they were expected to occupy. A sample phase diagram calculated between two Group 1 elements was in good agreement with experiment. Phase boundaries of fcc +bcc regions adjacent to terminal solid solutions in several Group 1/Group 2 and Group 1/Group 3 systems, on the other hand, were quite unsatisfactory. This difficulty was traced to the high, positive regular solution constants calculated for both phases. Such constants were shown to result from the downward concavity of a plot of enthalpy of vaporizationvs Group No. in the Nos. 1 to 3 region; in the Nos. 4 to 10 range this plot is concave upward. 相似文献
4.
K. F. Michaels W. F. Lange J. R. Bradley H. I. Aaronson 《Metallurgical and Materials Transactions A》1975,6(11):1843-1848
The Kaufman approach to phase equilibria involving primarily the fcc, bcc and hcp phases was examined outside the Group Nos.
4 to 10 range where it is customarily employed. The “stability parameters” (ΔH and ΔS of transformation) for most elements in the Group Nos. 1 to 3 region were found to fit satisfactorily the correlation curves
of stability parametervs group no.; some of the parameters for Al, Be, Mg and Ti, however, did not. The rare earth parameters fit well in the Group
No. 3.5 position they were expected to occupy. A sample phase diagram calculated between two Group 1 elements was in good
agreement with experiment. Phase boundaries of fcc +bcc regions adjacent to terminal solid solutions in several Group 1/Group
2 and Group 1/Group 3 systems, on the other hand, were quite unsatisfactory. This difficulty was traced to the high, positive
regular solution constants calculated for both phases. Such constants were shown to result from the downward concavity of
a plot of enthalpy of vaporizationvs Group No. in the Nos. 1 to 3 region; in the Nos. 4 to 10 range this plot is concave upward. 相似文献
5.
相图计算在TiAl基金属间化合物结构设计中的应用 总被引:1,自引:0,他引:1
为加速高性能TiAl基金属间化合物的研发,以相图热力学计算结果为基础,研究合金化元素Nb、W、B和热处理温度、冷却速度对TiAl基金属间化合物的相转变、微观结构的影响。研究结果表明:对成分为Ti-45Al—7Nb-0.4W-0.15B(原子百分比)的TiAl基金属间化合物在1450℃进行均匀化退火处理,高温下的α相经炉冷可以得到完全由α2/γ片层团构成的较为粗大的全片层组织;在1235℃进行均匀化热处理可以获得细小的双态组织。上述关键性的热处理实验和微观结构分析证实了理论计算结果的可行性。 相似文献
6.
《Canadian Metallurgical Quarterly》2013,52(3):257-264
AbstractThe relative partial thermodynamic properties of Cd in liquid Cd-Pb-Sn alloys have been investigated in the temperature range 680–840K by an emf technique. Data have been represented by general , power series expansions in the composition variables, and the liquidus surfaces when Cd or Sn are the primary crystallization products have been calculated analytically. Résumé Les propriétés thermodynamiques partielles du cadmium dans les alliages Cd-Pb-Sn liquide ont été étudiées dans une fourchette de température comprise entre 680 et 840K par la mesure de force électromotrice. Les données sont représentées par un développement en série des variables de composition. Les surfaces du liquidus ont été calculces analytiquement dans le cas où le cadmium ou l' étain est le produit prima ire de cristallisation. 相似文献
7.
8.
Yu. I. Ustinovshikov 《Russian Metallurgy (Metally)》2009,(5):437-440
Experimental results that are obtained by electron microscopy, X-ray diffraction, and carbide analysis and indicate the precipitation
of carbon atoms clusters in a hypereutectoid steel during its annealing above the eutectoid temperature are presented. These
results are compared to the reported data in order to construct a new Fe-C phase diagram, where cementite forms below the
eutectoid temperature due to the tendency of the Fe-C system toward ordering and carbon unbound to iron precipitates above
this temperature in the form of clusters or graphite particles due to the tendency of this system toward phase separation. 相似文献
9.
E. H. Du Marchie van Voorthuysen D. O. Boerma N. C. Chechenin 《Metallurgical and Materials Transactions A》2002,33(8):2593-2598
Iron layers are nitrided in mixtures of ammonia and hydrogen at low temperatures, using a thin nickel caplayer as a catalyst.
In the coordinate field of inverse temperature vs nitriding potential, we determined the boundaries between areas in which the α, γ′, or ε phases are in thermal equilibrium. Using these data, the Fe-N phase diagram is extended from 350 °C to 240 °C and extrapolated
down to 200 °C. The α, γ′, and ε phases probably coexist in a triple point in the Lehrer diagram around 214 °C. 相似文献
10.
Lars-Ingvar Staffansson 《Metallurgical and Materials Transactions B》1976,7(1):131-134
Using a DTA technique the melting point of pure MnS has been determined to 1655 ±5°C. The monotectic temperature in the Mn-MnS
system was found to be 1570 ±5°C. With these new data a thermodynamic analysis of the Mn-MnS system was carried out applying
a previously developed thermodynamic model. 相似文献
11.
12.
Calculation of the titanium-aluminum phase diagram 总被引:1,自引:0,他引:1
Joanne L. Murray 《Metallurgical and Materials Transactions A》1988,19(2):243-247
The Ti-Al phase diagram has been calculated by optimization of Gibbs energies with respect to phase diagram and thermochemical
data.T
0
curves, the locus of compositions and temperatures where the Gibbs energies of the liquid and one of the solid phases are
equal, have been calculated over the entire composition range. In order to assure physically reasonable extrapolations of
theT
0
curves of the ordered phases far from their equilibrium stability ranges, the Bragg-Williams approximation was used to provide
start values for the empirical optimizations. This approximation led to good convergence of the optimizations, and only small
deviations from the Bragg-Williams Gibbs energies were needed to obtain excellent agreement with experimental data. 相似文献
13.
An associated solution model is applied to describe the thermodyanmic properties of the liquid Ni-S phase. This model assumes
the existence of ‘NiS’ (l) species in the liquid in addition to Ni(l) and S(l). With two solution parameters for the binaries
Ni-‘NiS’ and ‘NiS’-S, this model is able to describe the thermodynamic behavior of the liquid phase over a wide range of temperature
and composition. Using this model for the liquid phase, a statistical thermodynamic model for the monosulfide phase and empirical
thermodynamic equations for β1-Ni3S2 and β2-Ni4S3, the Ni-S phase diagram is calculated. The calculated diagram is in excellent agreement with the available experimental data
with the exception that the eutectic composition for the equilibrium L1 + δ + η and those of the two liquids for the equilibriumL
1
+ L
2
+ η differ from the experimental data by more than 2 at. pct S.
Formerly Post-Doctorl Research Associate, University of Wisconsin-Milwaukee is now Lecturer, Department of Metallurgical Engineering,
Indian Institute of Technology, Kanpur, India 相似文献
14.
A. Saccone S. Delfino A. M. Cardinale R. Ferro 《Metallurgical and Materials Transactions A》2003,34(3):743-750
The dysprosium-zinc phase diagram has been investigated over its entire composition range by using differential thermal analysis,
(DTA) metallographic analysis, X-ray powder diffraction, and electron probe microanalysis (EPMA). Seven intermetallic phases
have been found and their structures confirmed. DyZn, DyZn2, Dy13Zn58, and Dy2Zn17 melt congruently at 1095 °C, 1050 °C, 930 °C, and 930 °C, respectively. DyZn3, Dy3Zn11, and DyZn12 form through peritectic reactions at 895 °C, about 900 °C and 685 °C, respectively. Four eutectic reactions occur at 850
°C and 30.0 at pct Zn (between (Dy) and DyZn), 990 °C and 60.0 at pct Zn (between DyZn and DyZn2), 885 °C and 76.0 at pct Zn (between DyZn3 and Dy3Zn11), and 875 °C and 85.0 at pct Zn (involving Dy13Zn58 and Dy2Zn17). The Dy-rich end presents a catatectic equilibrium; a degenerate invariant effect has been found in the Zn-rich region.
The phase equilibria of the Dy-Zn alloys are discussed and compared with those of the other known RE-Zn systems (RE=rare earth
metal) in view of the regular change in the relative stabilities of the phases across the lanthanide series 相似文献
15.
An associated solution model is applied to describe the thermodynamic behavior of Fe-S liquid. This model assumes the existence
of ‘FeS’ species in addition to Fe and S in the liquid. With two solution parameters for each of the binaries Fe-‘FeS’ and
‘FeS’-S, this model accounts for the compositional dependence of the thermodynamic properties of Fe-S liquid from pure Fe
to pure S over a wide range of temperature. The binary Fe-S does not contribute significantly to the excess Gibbs energy of
the liquid due to the rather small dissociation constant of ‘FeS’ to Fe and S. Using this model for the liquid phase and a
defect thermodynamic model for the pyrrhotite phase, the Fe-S phase diagram is calculated. The calculated diagram is in excellent
agreement with the experimental data, accounting for the range of homogeneity of pyrrhotite at all temperatures. Both the
thermodynamic and phase diagram data are obtained from the literature.
Formerly Post-Doctoral Research Associate, Materials Department, College of Engineering and Applied Science, University of
Wisconsin-Milwaukee. 相似文献
16.
17.
A. Saccone D. Macciò S. Delfino R. Ferro 《Metallurgical and Materials Transactions A》1999,30(5):1169-1176
The Nd-Au phase diagram was studied in the 0 to 100 at. pct Au composition range by differential thermal analysis (DTA), X-ray
diffraction (XRD), optical microscopy (LOM), scanning electron microscopy (SEM), and electron probe microanalysis (EPMA).
Six intermetallic phases were identified, the crystallographic structures were determined or confirmed, and the melting behavior
was determined, as follows: Nd2Au, orthorhombic oP12-Co2Si type, peritectic decomposition at 810 °C; NdAu, R.T. form, orthorhombic oP8-FeB type, H.T. forms, orthorhombic oC8-CrB type and, at a higher temperature, cubic cP2-CsCl type, melting point 1470 °C; Nd3Au4, trigonal hR42-Pu3Pd4 type, peritectic decomposition at 1250 °C; Nd17Au36, tetragonal tP106-Nd17Au36 type, melting point 1170 °C; Nd14Au51, hexagonal hP65-Gd14Ag51 type, melting point 1210 °C; and NdAu6, monoclinic mC28-PrAu6 type, peritectic decomposition at 875 °C. Four eutectic reactions were found, respectively, at 19.0 at. pct Au and 655 °C,
at 63.0 at. pct Au and 1080 °C, at 72.0 at. pct Au and 1050 °C, and, finally, at 91.0 at. pct Au and 795 °C. A catatectic
decomposition of the (βNd) phase, at 825 °C and ≈1 at. pct Au, was also found. The results are briefly discussed and compared to those for the other
rare earth-gold (R-Au) systems. A short discussion of the general alloying behavior of the “coinage metals” (Cu, Ag, and Au) with the rare-earth
metals is finally presented. 相似文献
18.
Metallographie, thermal, and X-ray techniques were used to determine the phase relations in the Nd-Zn system. Eight compounds,
three eutectics and a eutectoid were found. The compounds NdZn, NdZn2, and Nd2Znn melt congruently at 923°, 925°, and 981°C respectively. The compounds Nd3Zn11, NdZn4.46, and Nd3Zn22 undergo peritectic decomposition at 870°, 902°, and 950°C respectively, while NdZn3 undergoes peritectoid decomposition at 849°C. The eutectics occur at 12 wt pct Zn and 630°C, 38 wt pct Zn and 868°C, and
56 wt pct Zn and 854°C. The eutectoid occurs at 4 wt pct Zn and 622°C. The existence of a NdZn12 phase of the SmZn12 type structure has been confirmed. An allotropie transformation between the tetragonal NdZn11 structure and the hexagonal NdZn12 defect structure is proposed. 相似文献
19.
20.
E. A. Luk’yanova L. L. Rokhlin T. V. Dobatkina I. G. Korol’kova 《Russian Metallurgy (Metally)》2011,(5):484-490
Differential thermal, electron microprobe, and X-ray diffraction analyses and metallography are used to study Mg-Sm-Tb alloys
containing up to 30% Sm or Tb. Polythermal sections and the solidification surface of the Mg-Sm-Tb phase diagram are constructed
for the Mg-rich region. In the composition range under study, nonvariant transition-type equilibrium L + Mg24Tb5 = (Mg) + Mg41Sm5 is found to exist at a temperature of 539°C. 相似文献