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1.
After a short introduction to the theoretical background of thermally activated glide of dislocations, a constitutive model
is presented, which describes the temperature and strain-rate dependence of the flow stress. The properties of this constitutive
equation were estimated for several plain carbon steels in normalized conditions, for quenched and tempered low-alloy steels,
as well as for some high-strength low-alloy (HSLA) steels based on the temperature dependence and strain-rate sensitivity
of the flow stress at temperatures 81 K≤T≤398 K and strain rates 5 · 10−5 s−1≤ε≤1 · 10−2 s−1. The constitutive equation enables the extrapolation of flow-stress data to higher strain rates (ε≲10+4 s−1), which are in good agreement with the results obtained from high strain-rate deformation tests. The influence of solute-alloying
elements on the thermal stress, the activation enthalpy, and the constitutive parameters will be discussed.
This article is based on a presentation given in the symposium entitled “Dynamic Behavior of Materials-Part II,” held during
the 1998 Fall TMS/ASM Meeting and Materials Week, October 11–15, 1998, in Rosemont, Illinois, under the auspices of the TMS
Mechanical Metallurgy and the ASM Flow and Fracture Committees. 相似文献
2.
After a short introduction to the theoretical background of thermally activated glide of dislocations, a constitutive model
is presented, which describes the temperature and strain-rate dependence of the flow stress. The properties of this constitutive
equation were estimated for several plain carbon steels in normalized conditions, for quenched and tempered low-alloy steels,
as well as for some high-strength low-alloy (HSLA) steels based on the temperature dependence and strain-rate sensitivity
of the flow stress at temperatures 81 K≤T≤398 K and strain rates 5·10−5 s−1≤ε≤1·10−2s−1. The constitutive equation enables the extrapolation of flow-stress data to higher strain rates (ε<~10
+4s−1), which are in good agreement with the results obtained from high strain-rate deformation tests. The influence of solute-alloying
elements on the thermal stress, the activation enthalpy, and the constitutive parameters will be discussed.
This article is based on a presentation given in the symposium entitled ‘Dynamic Behavior of Materials-Part II,” held during
the 1998 Fall TMS/ASM ASM Meeting and Materials Week, October 11–15, 1998, in Rosemont, Illinois, under the auspices of the
TMS Mechanical Metallurgy and the ASM Flow and Fracture Committees. 相似文献
3.
The equilibrated grain boundary groove shapes for solid Zn in equilibrium with the ZnMg eutectic liquid were observed on rapidly
quenched samples. The Gibbs–Thomson coefficient for the solid Zn has been determined to be (10.64± 0.43) × 10−8 K m from the observed grain boundary groove shapes with the present numerical model, and the solid-liquid interfacial energy
for the solid Zn in equilibrium with the ZnMg eutectic liquid has been obtained to be (89.16 ± 8.02) × 10−3Jm−2 from the Gibbs–Thomson equation. The grain boundary energy for the solid Zn has also been calculated to be (172.97 ± 20.76)
× 10−3J m−2 from the observed grain boundary groove shapes.
This article is based on a presentation made in the symposium entitled ”Solidification Modeling and Microstructure Formation:
In Honor of Professor John Hunt” which occurred March 13-15, 2006, during the TMS Spring Meeting in San Antonio, Texas, under
the auspices of the TMS Materials Processing and Manufacturing Division, Solidification Committee. 相似文献
4.
Experiment reveals the characteristics of stable damping in a multiphase Al-Zn eutectoid alloy as follows: (1) the whole damping
(Q
−1) has the same dependence on measuring frequency (f);i.e., Q
-1 ∝f
−n
, wheren is a parameter independent of temperature; (2) in a low-temperature (low-T) and low-strain-amplitude (low-A
ε) region,Q
−1 = (B/f
n) exp (-nH/kT) (whereB is a constant,H is the phase interface or interphase boundary atom diffusion activation energy,k is Boltzmann’s constant, andT is the absolute temperature);n andH are independent ofA
ε. The damping originates from an anelastic motion of phase interface; (3) in an intermediate region, including low-T and high-A
ε, middle-T and middle-A
ε, and high-T and low-A
ε regions, we still have the equationQ
−1 = (C/f
n
) exp (-nH/kT), but the damping has a normal amplitude effect:C, n, andH all vary withA
ε. The damping results from a nonlinear relaxation of phase interface; and (4) in a high-T and high-A
ε region, there is no longer a linear relationship between InQ
−1 and 1/T, whereas relationQ
−1 ∝f
−n
is still satisfied;n increases asA
ε increases; and the damping has a normal amplitude effect, but it is weaker than that in case (3). The damping may be attributed
to another kind of nonlinear relaxation between phase interfaces. 相似文献
5.
The onset of plasticity during nanoindentation of a tungsten single crystal was examined as a function of pre-existing dislocation
density. Vickers indentations were used to generate a spatially varying dislocation density, and nanoindentation was then
carried out at regions of high and low dislocation densities. Even with dislocation densities as high as 1.8 × 1013 m−2, a sharp elastic-plastic transition was observed during some indentations. At lower dislocation densities, 3.5 × 109 m−2, the shear stress at the elastic plastic transition increased and approached the theoretical shear stress of the crystal.
A first-order model that predicts the load required for the onset of plasticity during nanoindentation from the activation
of a dislocation source within a critical volume of material, rather than homogeneous dislocation nucleation, is developed.
The model correlates well with experimentally measured loads at the onset of plasticity for dislocation densities of 1012 m−2 and higher for these nanoindentation conditions.
This article is based on a presentation given in the symposium entitled “Deformation and Fracture from Nano to Macro: A Symposium
Honoring W.W. Gerberich’s 70th Birthday,” which occurred during the TMS Annual Meeting, March 12–16, 2006 in San Antonio,
Texas and was sponsored by the Mechanical Behavior of Materials and Nanomechanical Behavior Committees of TMS. 相似文献
6.
Hans Conrad 《Metallurgical and Materials Transactions A》2004,35(9):2681-2695
Data in the literature on the effect of grain size (d) from millimeters to nanometers on the flow stress of Cu are evaluated. Three grain-size regimes are identified: regime I,
d>∼10−6 m; regime II, d ≈10−8 to 10−6 m; and regime III, d<∼10−8 m. Grain-size hardening occurs in regimes I and II; grain-size softening occurs in regime III. The deformation structure
in regime I consists of dislocation cells; in regime II, the dislocations are mostly restricted to their slip planes; in regime
III, computer simulations indicate that dislocations are absent and that deformation occurs by the shearing of grain-boundary
atoms. The transition from regime I to II occurs when the dislocation cell size becomes larger than the grain size, and the
transition from regime II to III occurs when the dislocation spacing due to elastic interactions becomes larger than the grain
size. The rate-controlling mechanism in regime I is concluded to be the intersection of dislocations; in regime II, it is
proposed to be grain-boundary shear promoted by the pileup of dislocations; in regime III, it appears to be grain-boundary
shear by the applied stress alone.
This article is based on a presentation given in the symposium “Dynamic Deformation: Constitutive Modeling, Grain Size, and
Other Effects: In Honor of Prof. Ronald W. Armstrong,” March 2–6, 2003, at the 2003 TMS/ASM Annual Meeting, San Diego, California,
under the auspices of the TMS/ASM Joint Mechanical Behavior of Materials Committee. 相似文献
7.
High-damping metals and alloys 总被引:15,自引:0,他引:15
High-Damping Metals (HIDAMETS) are the physical metallurgist’s answer to unwanted noise and vibrations. However, the characterization
of the damping properties of metals and alloys is neither simple nor straightforward. This is mainly because the damping mechanisms
involved depend upon the stress-induced movement of defects in the metal in question which, in turn, implies a dependence
upon the microstructure (thermomechanical history) of the sample. To properly characterize the damping performance of a HIDAMET
in a well-defined structural state, one must measure the mechanical damping as a function of vibration frequency, temperature,
vibration strain amplitude, and static bias load over the ranges of these variables to be encountered in the application in
question. This requires the use of a variety of equipment adapted to different modes of vibration and their overtones, especially
when the damping is nonlinear (amplitude-dependent). Our approach to this problem is described and illustrated by test results
obtained on several HIDAMETS.
This paper is based on a presentation made in the symposium “Acoustic/Vibration Damping Materials” presented during the TMS
Fall Meeting, Indianapolis, IN, October 1–5, 1989, under the auspices of the TMS Physical Metallurgy Committee. 相似文献
8.
K. S. Raja S. A. Namjoshi D. A. Jones 《Metallurgical and Materials Transactions A》2005,36(5):1107-1120
Rupture of passive film is considered as an essential step in the stress corrosion cracking (SCC) process. At constant load,
accumulation of creep strain is often associated with the strain to passive film rupture. Therefore, low-temperature creep
behavior of a material is important from an SCC point of view. Constant load creep studies carried out on alloy 22 (a Ni-22Cr-13Mo-4W
alloy) in acidified chloride environments at 80 °C showed a logarithmic creep behavior. The creep strain decayed logarithmically
and reached values less than 4×10−9/s, which is lower than the detectable limit of laboratory scale SCC tests. 304 SS showed SCC failure in acidified chloride
solutions in simulated open circuit conditions. A steady-state creep strain rate could be observed during SCC failures, of
the order of 10−5 to 10−6/s. The high creep strain rate of 304 SS can be correlated to the observed higher corrosion currents, which were more than
40 times that observed in alloy 22. When the dissolution rate of alloy 22 was increased by impressing about 1 mA/cm2 anodic current, a steady-state creep strain rate of 6.5×10−8/s was observed. The results indicated that anodic dissolution increased the localized plasticity of the material, resulting
in creep strain. However, alloy 22 did not show SCC.
This article is based on a presentation made in the symposium “Effect of Processing on Materials Properties for Nuclear Waste
Disposition,” November 10–11, 2003, at the TMS Fall meeting in Chicago, Illinois, under the joint auspices of the TMS Corrosion
and Environmental Effects and Nuclear Materials Committees. 相似文献
9.
Dr. Milton Blander 《Metallurgical and Materials Transactions B》2000,31(4):579-586
Modern concepts and theories have created the ability to predict the thermodynamic properties of high-temperature liquid solutions
(molten salts, metals, and slags) and vapors. These advances have made it possible to calculate thermodynamic properties and
total chemistries for many technologically and scientifically important systems. Specific theories include (1) a cycle for
accurately calculating the solubility products of relatively insoluble salts in reciprocal molten salt systems, (2) the coordination
cluster theory, which allows one to predict the temperature and concentration dependence of the activities of a dilute solute
in a multicomponent system, (3) the conformal ionic-solution theory, which predicts the properties of reciprocal and additive
multicomponent molten salt systems, (4) the modified quasi-chemical theory, which predicts the properties of multicomponent
silicate (and other polymeric) systems, (5) a simple extension of polymer theory, which leads to methods for predicting the
sulfide capacities (as well as capacities for PO
4
3−
, SO
4
2−
, Cl−, Br−, I−, etc.) in molten silicates and other polymeric solvents, and (6) a dimensional theory for the prediction of nonelectronic entropies
and free-energy functions of vapor molecules. These accomplishments have helped to create computer programs which can calculate
realistic total chemistries of complex systems and have provided a method of extending the scope of fundamental thermodynamic
databases of vapors.
He was a Group Leader and Senior Scientist at the Argonne National Laboratory until 1996 when he retired.
This article is based on a presentation made at “The Milton Blander Symposium on Thermodynamic Predictions and Applications”
at the TMS Annual Meeting in San Diego, California, on March 1–2, 1999, under the auspices of the TMS Extraction and Processing
Division and the ASM Thermodynamics and Phase Equilibrium Committee. 相似文献
10.
Stephen E. Grunschel Rodney J. Clifton 《Metallurgical and Materials Transactions A》2007,38(12):2885-2890
This study uses the pressure-shear plate impact configuration to investigate the rate-controlling mechanisms of the dynamic
plastic response of aluminum at strain rates of approximately 106 s−1 and at temperatures that approach melt. To achieve this combination of high strain rates and high temperatures, pressure-shear
plate impact experiments are being conducted with modifications introduced by Frutschy[1] to enable the experiments to be conducted at high temperatures. So far, the shearing resistance has been measured at temperatures
up to 906 K (632 °C), which is 81 pct of the melting temperature at the concurrent pressure. Several approaches are being
explored to obtain even higher fractions of the melting temperature, possibly exceeding it.
This article is based on a presentation made in the symposium entitled “Dynamic Behavior of Materials,” which occurred during
the TMS Annual Meeting and Exhibition, February 25–March 1, 2007 in Orlando, Florida, under the auspices of The Minerals,
Metals and Materials Society, TMS Structural Materials Division, and TMS/ASM Mechanical Behavior of Materials Committee. 相似文献
11.
J. P. Fowler M. J. Worswick A. K. Pilkey H. Nahme 《Metallurgical and Materials Transactions A》2000,31(13):831-844
Quantitative metallographic studies of damage evolution leading to ductile fracture under high strainrate loading conditions
are presented. A model material is considered, namely, leaded brass, which contains a dispersed globular lead phase that acts
as void nucleation sites. Interrupted tensile split Hopkinson bar tests have been performed to capture the evolution of porosity
and void aspect ratio with deformation at strain rates up to 3000 s−1. Both uniaxial and notched specimen geometries were considered to allow the effects of remote stress triaxiality to be investigated.
Plate impact testing has also been performed to investigate the evolution of damage under the intense tensile triaxiality
and extremely high rates of deformation (105 s−1) occurring within a spall layer. Quantitative metallographic measurements of damage within deformed specimens are used to
assess predictions from a Gursonbased constitutive model implemented within an explicit dynamic finite element code. A stresscontrolled
void nucleation treatment is shown to capture the effect of triaxiality on damage initiation for the range of experiments
considered.
J.P. FOWLER, formerly Research Associate with the Mechanical and Aerospace Engineering Department, Carleton University
This article is based on a presentation given in the symposium entiled “Dynamic Behavior of Materials—Part II,” held during
the 1998 Fall TMS/ASM Meeting and Materials Week, October 11–15, 1998, in Rosemont, Illinois, under the auspices of the TMS
Mechanical Metallurgy and the ASM Flow and Fracture Committees. 相似文献
12.
J. P. Fowler M. J. Worswick A. K. Pilkey H. Nahme 《Metallurgical and Materials Transactions A》2000,31(3):831-844
Quantitative metallographic studies of damage evolution leading to ductile fracture under high strain-rate loading conditions
are presented. A model material is considered, namely, leaded brass, which contains a dispersed globular lead phase that acts
as void nucleation sites. Interrupted tensile split Hopkinson bar tests have been performed to capture the evolution of porosity
and void aspect ratio with deformation at strain rates up to 3000 s−1. Both uniaxial and notched specimen geometries were considered to allow the effects of remote stress triaxiality to be investigated.
Plate impact testing has also been performed to investigate the evolution of damage under the intense tensile triaxiality
and extremely high rates of deformation (105 s−1) occurring within a spall layer. Quantitative metallographic measurements of damage within deformed specimens are used to
assess predictions from a Gurson-based constitutive model implemented within an explicit dynamic finite element code. A stress-controlled
void nucleation treatment is shown to capture the effect of triaxiality on damage initiation for the range of experiments
considered.
This article is based on a presentation given in the symposium entitled “Dynamic Behavior of Materials—Part II,” held during
the 1998 Fall TMS/ASM Meeting and Materials Week, October 11–15, 1998, in Rosemont, Illinois, under the auspices of the TMS
Mechanical Metallurgy and the ASM Flow and Fracture Committees. 相似文献
13.
Damping characteristics of TiNi shape memory alloys 总被引:10,自引:0,他引:10
The damping characteristics of TiNi SMAs have been systematically studied by using techniques of resonant-bar and low-frequency
inverted torsion pendulum. Experimental results show that both the martensite phase (M) and R phase (R) have high damping
due to the movement of twin boundaries. Because the B2 parent phase (B2) has smaller damping, it is suggested that this may
come from the dynamic ordering process of lattice defects. In the transformation re-gions of B2 ↔ M, B2 ↔ R, and R ↔ M, there
are maxima of the damping capacity which are attributed to two contributions. One arises from the plastic strain and twin-interface
move-ment during the thermal transformation, which obeys a linear variation of peak heightsQ
−1
max vst att ≥ 1 °C/min. The other originates from the stress-induced transformation formed by the applied external stress which dominates
atT < 1 °C/min. The elastic modulusE of martensite and the R phase is lower than that of the B2 phase, and a modulus minimum appears in the transformation region. 相似文献
14.
Toshiji Mukai Koichi Ishikawa Kenji Higashi 《Metallurgical and Materials Transactions A》1995,26(10):2521-2526
Three IN905XL aluminum alloys with fine grain (1 μm), intermediate grain (3 μm), and coarse grain (5 μm) have been developed
by a combination of mechanical alloying (MA) and conventional extrusion in order to investigate their mechanical properties
at dynamic strain rates of 1 × 103 and 2 × 103 s−1 and a quasi-static strain rate of 10-3 s−1. Flow stresses are found to increase with decreasing grain size for all the strain rates tested. Negative strain-rate sensitivity
of flow stress is observed up to 1 × 103 s−1 in both intermediate- and coarse-grained IN905XL. At the highest strain rate of 2 × 103 s−1 however, all samples showed a positive strain-rate sensitivity of strength. Total elongation at high strain rates is generally
larger than that at low strain rates. Total elongation also decreases with grain size for all the strain rates. This decrease
in elongation results from an initiation of microcracks at interfaces between the matrix and particles finely dispersed near
grain boundary regions, introduced during MA processing; then, this initiation leads elongation of alloys to small limited
values.
Formerly with the Department of Mechanical Systems Engineering, University of Osaka Prefecture.
This article is based on a presentation made in the symposium “Dynamic Behavior of Materials,” presented at the 1994 Fall
Meeting of TMS/ASM in Rosemont, Illinois, October 3-5, 1994, under the auspices of the TMS-SMD Mechanical Metallurgy Committee
and the ASM-MSD Flow and Fracture Committee. 相似文献
15.
The relaxation process and glass transition kinetics of the La55Al25Ni10Cu10 bulk metallic glass (BMG) below the calorimetric glass transition were investigated by differential scanning calorimetry.
Enthalpy relaxation was observed in isothermal annealing experiments below the glass transition temperature T
g
. The time-dependent enthalpy relaxations were well described by a stretched exponential relaxation function, with an exponential
index 0.78. An apparent activation energy E = 60.8 kJ/mol was derived from the temperature dependence of the relaxation time. The equilibrium free volume concentration
at a temperature about 30 K below T
g
is 10−17 to 10−13, calculated using an empirical Vogel–Fulcher–Tammann (VFT) type equation.
This article is based on a presentation given in the symposium entitled “Bulk Metallic Glasses IV,” which occurred February
25–March 1, 2007 during the TMS Annual Meeting in Orlando, Florida under the auspices of the TMS/ASM Mechanical Behavior of
Materials Committee. 相似文献
16.
Vibration damping characteristics of laminated steel sheet 总被引:3,自引:0,他引:3
The use of laminated steel sheets as vibration damping materials was studied. The laminate consisted of a viscoelastic layer
which was sandwiched between two steel sheets. The study sought to identify parameters affecting the damping efficiency of
the laminate. Two viscoelastic materials, a copolymer based on ethylene and acrylic acid (PEAA) and polyvinyl butyral (PVB),
were used. A frequency analyzer was used to measure the loss factor of the laminates. A theoretical analysis of damping efficiency
based on a model described by Ungar[2] was also carried out. The results showed that the loss factor of the PEAA-based laminates increased monotonically with increasing
thickness of the viscoelastic layer and leveled off at 25.9 pct of total thickness. Ungar’s theory predicted a higher loss
factor than the experimental data. This might have resulted from interfacial adhesive bonding, a nonuniform viscoelastic layer
thickness, and the extrapolation of the rheological data from low to high frequencies. The loss factor of the laminate increased
with increasing temperature, reached a maximum value, and then decreased. An optimum temperature for maximum damping was found
for each laminate configuration. The PEAA-based laminates possessed higher damping efficiency than the PVB-based laminates
at room temperature. The symmetric laminate (with the same steel sheet thickness) possessed a better damping efficiency than
asymmetric laminates. The maximum damping peak of the laminates using a polymer blend, when compared to the laminates using
unblended resin, exhibited a lower loss factor value, became broader, and occurred at a temperature between theT
g’s of the individual components of the polymer blend.
This paper is based on a presentation made in the symposium “Acoustic/Vibration Damping Materials” presented during the TMS
Fall Meeting, Indianapolis, IN, October 1–5, 1989, under the auspices of the TMS Physical Metallurgy Committee. 相似文献
17.
High-temperature deformation behavior of a gamma TiAl alloy—Microstructural evolution and mechanisms
Jeoung Han Kim Graduate Ph.D. Candidate Student Young Won Chang Chong Soo Lee Tae Kwon Ha 《Metallurgical and Materials Transactions A》2003,34(10):2165-2176
The present investigation was carried out in the context of the internal-variable theory of inelastic deformation and the
dynamic-materials model (DMM), to shed light on the high-temperature deformation mechanisms in TiAl. A series of load-relaxation
tests and tensile tests were conducted on a fine-grained duplex gamma TiAl alloy at temperatures ranging from 800 °C to 1050
°C. Results of the load-relaxation tests, in which the deformation took place at an infinitesimal level (ε ≅ 0.05), showed that the deformation behavior of the alloy was well described by the sum of dislocation-glide and dislocation-climb
processes. To investigate the deformation behavior of the fine-grained duplex gamma TiAl alloy at a finite strain level, processing
maps were constructed on the basis of a DMM. For this purpose, compression tests were carried out at temperatures ranging
from 800 °C to 1250 °C using strain rates ranging from 10 to 10−4/s. Two domains were identified and characterized in the processing maps obtained at finite strain levels (0.2 and 0.6). One
domain was found in the region of 980 °C and 10−3/s with a peak efficiency (maximum efficiency of power dissipation) of 48 pct and was identified as a domain of dynamic recrystallization
(DRx) from microstructural observations. Another domain with a peak efficiency of 64 pct was located in the region of 1250
°C and 10−4/s and was considered to be a domain of superplasticity.
This article is based on a presentation made in the symposium entitled “Fundamentals of Structural Intermetallics,” presented
at the 2002 TMS Annual Meeting, February 21–27, 2002, in Seattle, Washington, under the auspices of the ASM and TMS Joint
Committee on Mechanical Behavior of Materials. 相似文献
18.
Y. Li J. A. Lucas G. M. Evans I. P. Ratchey G. R. Belton 《Metallurgical and Materials Transactions B》2000,31(5):1049-1057
The interfacial reaction rate between liquid iron oxide and CO-CO2 was determined using a thermogravimetric technique. The measured rates were controlled by the chemical reactions at the gas-slag
interface. The apparent first-order rate constant, for the oxidation of liquid iron oxide by CO2, decreased sharply with the equilibrium CO2/CO ratio. The rate of reduction of liquid iron oxide by CO showed a slight increase with the oxidation state of the melt.
At 1773 K, the apparent first-order rate constants are given by k=4.0×10−5(CO2/CO)−0.8 and k=4.0 × 10−5(CO2/CO)0.18 mol cm−2 s−1 atm−1 for the oxidation and reduction, respectively. The addition of basic oxides, such as BaO and CaO, resulted in an increased
reaction rate, while the addition of acidic oxide, such as SiO2, decreased the rate. The results are consistent with the dissociation or formation of the CO2 molecule, involving the transfer of two charges, being the rate controlling mechanism of the reactions.
This article is based on a presentation made in the “Geoffrey Belton Memorial Symposium,” held in January 2000, in Sydney,
Australia, under the joint sponsorship of ISS and TMS. 相似文献
19.
Trapping of hydrogen by sulfur-associated defects in steel 总被引:1,自引:0,他引:1
M. Iino 《Metallurgical and Materials Transactions A》1985,16(3):401-409
Reversible and irreversible trapping behaviors of sulfur-associated defects in steel were studied through electrochemical
hydrogen permeation experiments and the results were analyzed to obtain the follow-ing information: an apparent diffusion
constant of hydrogen influenced by reversible and irreversible trapping by sulfur-associated defects,D *, was shown to be given as a function of sulfur content, S, in wt ppm.byD * = 1.12·10−6(1 + 0.0933S0.548)−1cm2 s−1. Associated parameters of reversible and irreversible trapping, λ/μ and k, were also expressed as a function of sulfur content,
S. Both parameters, λ/μ, and k, are shown to increase with S, suggesting an increase of both reversible and irreversible trap
sites with increase in sulfur content in steel. 相似文献
20.
Y. Li R. J. Fruehan J. A. Lucas G. R. Belton 《Metallurgical and Materials Transactions B》2000,31(5):1059-1068
Measurements have been made of the chemical diffusion coefficient of oxygen in liquid iron oxide at temperatures from 1673
to 1888 K and in a calcium ferrite (Fe/Ca = 2.57) at temperatures from 1573 to 1873 K. A gravimetric method was used to measure
the oxygen uptake during the oxidation of the melts by oxygen or CO2-CO mixtures. The rate was shown to be controlled by mass transfer in the liquid melt. The chemical diffusivity of oxygen
in liquid iron oxide at oxygen potential between air and oxygen was found to be 4.2±0.3 × 10−3 cm2/s at 1888 K. That in iron oxide at oxidation state close to iron saturation was established to be given by the empirical
expression log D=−6220/T + 1.12 for temperatures between 1673 and 1773 K. For the calcium ferrite (Fe/Ca=2.57) at oxygen potential between air and
oxygen, the diffusivity of oxygen was found to be given by log D=−1760/T−1.31 for temperatures between 1673 and 1873 K.
This article is based on a presentation made in the “Geoffrey Belton Memorial Symposium,” held in January 2000, in Sydney,
Australia, under the joint sponsorship of ISS and TMS. 相似文献