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1.
J. H. Selverian A. R. Marder M. R. Notis 《Metallurgical and Materials Transactions A》1989,20(3):543-555
The effect of various silicon levels on the reaction between iron panels and Al-Zn-Si liquid baths during hot dipping at 610°C
was studied. Five different baths were used: 55Al−0.7Si−Zn, 55Al−1.7Si−Zn, 55Al−3.0Si−Zn, 55Al−5.0Si−Zn, and 55Al−6.88Si−Zn
(in wt pct). The phases which formed as a result of this reaction were identified as Fe2Al5 and FeAl3 (binary Fe−Al phases with less than 2 wt pct Si and Zn in solution),T1, T2, T4, T8, andT
5H (ternary Fe−Al−Si phases), andT
5C (a quaternary Fe−Al−Si−Zn phase). Compositional variations through the reaction zone were determined. The phase sequence
in the reaction zone of the panel dipped for 3600 seconds in the 1.7 wt pct Si bath was iron panel/(Fe2Al5+T
1)/FeAl3/(T
5H+T
5C)/overlay. In the panel dipped for 1800 seconds in the 3.0 wt pct Si bath the reaction zone consisted of iron panel/Fe2Al5/(Fe2Al5+T
1)/T
1/FeAl3/(FeAl3+T
2)/T
5H/overlay. In the panel dipped for 3600 seconds in the 6.88 wt pct Si bath the phase sequence was iron panel/Fe2Al5/(Fe2Al5+T1)/(T1+FeAl3)/(T1+T2)/T2/T8/T4/overlay. The growth kinetics of the reaction zone were also studied. A minimum growth rate for the reaction zone which formed
from a reaction between the iron panel and molten Al−Zn−Si bath was found in the 3.0 wt pct Si bath. The growth kinetics of
the reaction layers were found to be diffusion controlled in the 0.7, 1.7, and 6.88 wt pct Si baths, and interface controlled
in the 3.0 and 5.0 wt pct Si baths. The presence of the interface between theT2/T5H, Fe2Al5/T
1, orT
1/FeAl3 phases is believed responsible for the interface controlled growth kinetics exhibited in the 3.0 and 5.0 wt pct Si baths. 相似文献
2.
S. M. Skolianos T. Z. Kattamis O. F. Devereux 《Metallurgical and Materials Transactions A》1989,20(11):2499-2516
The microstructure and corrosion behavior of as-cast and heat-treated Al-4.5 pct Cu-2.0 pct Mn alloy specimens solidified
at various cooling rates were investigated. The equilibrium phases Al6Mn and θ-Al2Cu, which are observed in the conventionally solidified alloy in the as-cast condition, were not detected in rapidly solidified
(melt-spun) material. Instead, the ternary compound Al20Cu2Mn3 was present in addition to the α phase, which was present in all cases. The morphological and kinetic nature of corrosion
was investigated metallographically and through potentiostatic techniques in 3.5 wt pct NaCl aqueous solution. Corrosion of
the as-cast material was described by two anodic reactions: corrosion of the intermetallic phases and pitting of the α-Al
solid solution. The corrosion rate increased with cooling rate from that for the furnace-cooled alloy to that for the copper
mold-cast alloy and, subsequently, decreased in the rapidly solidified alloy. In the heat-treated material, corrosion could
be described by two anodic reactions: corrosion of Al20Cu2Mn3 precipitate particles and pitting of the α-Al matrix.
S.M. Skolianos, formerly Graduate Student, Department of Metallurgy, University of Connecticut 相似文献
3.
Z. W. Chen J. T. Gregory R. M. Sharp 《Metallurgical and Materials Transactions A》1992,23(9):2393-2400
The formation and growth of intermetallic phases during hot dipping of low carbon steel in a Galfan bath (5 wt pct Al-Zn plus
0.05 pct mischmetal) at 450 °C have been studied by using scanning electron microscopy, X-ray diffraction, and energy dispersive
spectroscopy (EDS). The first intermetallic phase to appear was in the form of local outbursts at the substrate/melt interface;
intermetallic phases subsequently developed a breakaway morphology. Both the inter- metallic outbursts and the breakaway were
found to be mixtures of Fe2Al5-Znx and FeAl3-Znx, the latter being in each case further away from the intermetallic/substrate interface. The initial outbursts were determined
to be mainly Fe2Al5-Znx; this phase grew into the substrate with a (001) preferred growth direction. The breakaway was mainly FeAl3-Znx with Fe2Al5-Znx found only close to the interface. Both intermetallic growth morphologies can be characterized by a reaction path of Fe (substrate)/Fe2Al5-Znx/FeAl3-Znx/galfan (melt). 相似文献
4.
5.
Fixed composition ratios of Fe and Zn corresponding to γ-(Fe3Zn110), Γ1-(Fe5Zn21), δ-(FeZn7), and ζ-(FeZn13) with the addition of 5 pct Al (wt) were ball milled in an argon gas atmosphere to form homogenous alloys. Nonisothermal
kinetic analyses of the mechanically alloyed materials, based on differential scanning calorimetry (DSC) measurements, revealed
two diffusion-controlled processes during the evolution of the δ+5 pct Al and ζ+5 pct Al compositions with activation energies of 227±2 and 159±1 kJ/mole, respectively. Other endothermic
and exothermic reactions detected for these compositions are consistent with the Fe-Zn-Al equilibrium phase systems with respect
to the formation of the Fe3Al, Fe2Al5, and δ-FeZn7 phases Based on the evidence of FeAl2 formation at 440 °C for the ζ+5 pct Al composition from X-ray diffraction (XRD) and DSC measurements, the revision/re-evaluation
of the Fe-Zn-Al equilibrium phase diagrams is proposed. The Γ+5 pct Al and Γ1+5 pct Al compositions evolved similarly through the same fields, except at 400 °C, where the former consisted of α-Fe + Γ + δ, while the later was without the Γ phase. 相似文献
6.
The aim of this work is to partially substitute Fe and Mn for Ni in the 3HA piston alloy and to study the consequences through
microstructural evaluation and the thermal analysis technique. Three types of near-eutectic alloys containing (2.6 wt pct
Ni-0.2 wt pct Fe-0.1 wt pct Mn), (1.8 wt pct Ni-0.75 wt pct Fe-0.3 wt pct Mn), and (1 wt pct Ni-1.15 wt pct Fe-0.6 wt pct
Mn) were produced, and their solidification was studied at the cooling rate of 0.9 K/s (°C/s) using the computer-aided thermal
analysis technique. Optical microscopy and scanning electron microscopy were used to study the microstructure of the samples,
and energy dispersive X-ray (EDX) analysis was used to identify the composition of the phases. Also, the quantity of the phases
was measured using the image analysis technique. The results show that Ni mainly participates as Al3Ni, Al9FeNi, and Al3CuNi phases in the high Ni-containing alloy (2.6 wt pct Ni). In addition, substitution of Ni by Fe and Mn makes Al9FeNi the only Ni-rich phase, and Al12(Fe,Mn)3Si2 appears as an important Fe-rich intermetallic compound in the alloys with the higher Fe and Mn contents. 相似文献
7.
Discussion of “Interfacial layer in coatings produced in molten Zn-Al eutectoid alloy containing Si”
Studies of the interfacial layer in coatings produced in a molten Zn-22.3 pct Al-0.4 pct Si alloy revealed a double layer
with an Fe2Al8Si sublayer on the top and an Fe2Al5 sublayer on the bottom. This suggests that a diffusion path is established during the hot-dipping stage, starting from the
liquid phase and passing through the phase fields of the ternary inhibition compound of Fe2Al8Si and all binary Fe-Al intermetallic compounds available in the Al-Fe system. Thermodynamic calculations of the free energies
of the relevant phases have confirmed the feasibility of such a diffusion path.
M. RANJAN, R. TEWARI, W.J. VAN OOIJ, and V.K. VASUDEVAN: Metall. Mater. Trans. A, 2004, vol. 35A, pp. 3707–20. 相似文献
8.
Yongzhong Zhan Zhulin Yang Honglou Mo Yong Du 《Metallurgical and Materials Transactions A》2012,43(1):29-36
Isothermal section of the Al–V–RE (RE = Gd, Ho) ternary systems at 773 K (500 °C) was investigated over the whole concentration
range by means of X-ray diffraction and scanning electron microscopy equipped with energy dispersive X-ray analysis. The crystal
structures of the Al43Mo4Ho6-type ternary compounds Al43V4RE6 were determined with Rietveld refinement method. The intermetallic compound Al43V4Gd6 belongs to the Space group P63/mcm, with cell parameters of a = b = 1.0996(6) nm, c = 1.7813(9) nm, α = β = 90 deg, γ = 120 deg, and volume of unit cell of 1.8658(9) nm3. At 773 K (500 °C), all the Al-rich ternary alumides, i.e., Al43V4Gd6, Al20V2Gd, Al43V4Ho6, and Al20V2Ho appear without any significant homogeneity region. Five binary compounds, i.e., AlV3, Al4Gd, Al17Gd2, Al17Ho2, and AlHo2 reported in the literature were not found. Fifteen and 14 ternary phase fields have been identified in the isothermal section
of the Al–V–Gd and Al–V–Ho ternary systems, respectively. The solid solubility of V in Al2RE3, AlRE, and Al2RE amounts to approximately 1.0 at. pct to 2.0 at. pct, whereas the solid solubility of Al in V is approximately 39 at. pct. 相似文献
9.
The precipitation reaction in an aluminum alloy containing 0.05 wt pct Fe (enriched in Fe57) was studied using Mössbauer spectroscopy. It was found that in addition to the equilibrium precipitate, Fe Al3, the metastable phase FeAl6 occurs as well. Formation of FeAl6 is favored when the rate of precipitation is accelerated by cold working the supersaturated alloy. Step anneal experiments were performed in an effort to determine an activation energy for growth of precipitate particles. The results of these experiments are not entirely consistent with simple models of the nucleation and growth process. 相似文献
10.
Chunliu Li Yongzhong Zhan Jia She Qingxiao Huang Mingjun Pang Wenchao Yang 《Metallurgical and Materials Transactions A》2012,43(1):20-28
The isothermal sections of the phase diagram of the Zr–Si–RE (RE=La and Er) systems at 773 K (500 °C) have been investigated
using X-ray power diffraction (XRD), scanning electron microscopy (SEM), and optical microscopy (OM) with the aid of metallographic
analysis. The existences of 10 binary compounds, namely ZrSi2, α-ZrSi, α-Zr5Si4, Zr3Si2, Zr2Si, RESi2, RESi2–x
, RESi, RE5Si4, and RE5Si3 have been confirmed in the Zr–Si–RE (RE=La and Er) systems, respectively. As for the reported binary compound RE3Si2, only La3Si2 has been observed in the Zr–Si–La system, whereas Er3Si2 was not found. No binary compound was found in the Zr–RE binary systems, and no ternary compound was found in the current
ternary systems. None of the phases in Zr–Si–La system reveals a remarkable solid solution at 773 K (500 °C). However, the
maximum solid solubility of Zr in Er, Er5Si3, Er5Si4, ErSi, ErSi1.67, and ErSi2 is determined to be approximately 12.0 at. pct, 2.4 at. pct, 3.0 at. pct, 3.3 at. pct, 2.2 at. pct, and 1.8 at. pct, respectively.
The maximum solid solubility of Er in ErSi2 is approximately 1.8 at. pct. No remarkable solid solubility of the elements in any of the other phases has been observed. 相似文献
11.
The rate of formation of intermetallic compounds between aluminum and three ferritic steels, one austenitic steel, and Inconel
has been determined by an electrolytic method. The steel was held at zero potential with respect to aluminum in a NaCl-AlCl3 melt, and the current measured. Comparison of measured thicknesses of intermetallic layers with those calculated from the
integrated current gives an average deposition efficiency of 95 pct. For the Type 304 austenitic steel thickness
(min), andk is given by logk= −6400/T(0K) +4.469. The ferritic steels show a linear rate of growth of Al5Fe2, with an initial higher rate such that extrapolation of the linear curve back to zero time gives an intercept of 16±7 μm.
The rate constants (mm min−1) may be represented by log (rate)=α/T+β, and the values of α and β are respectively −2650 and−0.788 for a plain carbon steel,−6580 and + 3.469 for a 1.3 pct Cr,
0.4 pct Mo steel, and−5950 and +2.466 for a 2.2 pct Cr, 0.9 pct Mo steel. The more highly alloyed steels are thus attacked,
more slowly. Results for Inconel could not be fitted to any simple equation. With the ferritic steels growth is by aluminum
diffusing inwards; with Inconel it is by nickel diffusing outward. 相似文献
12.
Frank W. Gayle Alexander J. Shapiro Francis S. Biancaniello William J. Boettinger 《Metallurgical and Materials Transactions A》1992,23(9):2409-2417
Isothermal sections of the Al-Cu-Fe equilibrium phase diagram at temperatures from 680 °C to 800 °C were determined in the
region with 50 to 75 at. pct Al and 0 to 25 at. pct Fe using scanning electron microscopy/energy dispersive spectroscopy (SEM/EDS)
techniques. This re- gion includes the face-centered icosahedral phase (Ψ-Al6Cu2Fe) which has unprecedented struc- tural perfection and no apparent phason strain. The icosahedral phase has equilibrium phase
fields with four distinct phases at 700 °C and 720 °C (β-Al(Fe, Cu), λ-Al13Fe4, ω-Al7Cu2Fe, and liquid) and three phases at 680 °C(β, ω, and λ) and 800 °C (β, λ, and liquid). The B2 ordered β phase has considerably greater solubility for Cu than previously
reported, extending from AlFe to ∼Al50Fe5Cu45. The equilibrium range of composition for the icosahedral phase at these temperatures was determined, and a liquidus projection
is proposed. 相似文献
13.
W. J. Boettinger L. Bendersky J. G. Early 《Metallurgical and Materials Transactions A》1986,17(5):781-790
Rapidly solidified powders of Al-8 wt pct Fe exhibit four distinct microstructures with increasing particle diameter in the
size range of 5 μm to 45 μm: microcellular α-Al; cellular α-Al; a-Al + Al6Fe eutectic; and Al3Fe primary intermetallic structure. Small powder particles (~10 μm or less) undercool significantly prior to solidification
and typically exhibit a two-zone microcellular-cellular structure in individual powder particles. In the two-zone microstructure,
there is a transition from solidification dominated by internal heat flow during recalescence with high growth rates (microcellular)
to solidification dominated by external heat flow and slower growth rates (cellular). The origin of the two-zone microstructure
from an initially cellular or dendritic structure is interpreted on the basis of growth controlled primarily by solute redistribution.
Larger particles experience little or no initial undercooling prior to solidification and do not exhibit the two-zone structure.
The larger particles contain cellular, eutectic, or primary intermetallic structures that are consistent with growth rates
controlled by heat extraction through the particle surface (external heat flow). 相似文献
14.
I. C. Barlow H. Jones W. M. Rainforth 《Metallurgical and Materials Transactions A》2001,32(12):2937-2945
The formation and coarsening of Al2O3 dispersoids have been investigated at 500 °C, 550 °C, and 600 °C in a mechanically alloyed (MA) extrusion of composition
Al-0.35wt pct Li-1wt pct Mg-0.25wt pct C-10vol pct TiO2 for times up to 1500 hours. In the as-extruded condition, the dispersed phases included Al3Ti, Al4C3, MgO, cubic TiO (C-TiO), monoclinic TiO (M-TiO), TiO2, and a small amount of Al2O3. However, numerous Al2O3 dispersoids (various polymorphs: η, γ, α, and δ) with “block-shaped” morphology were formed after heat treatment due to reduction of C-TiO, M-TiO, and TiO2. Transmission electron microscopy (TEM) and X-ray diffraction (XRD) showed conclusively the transformation of these phases
to additional Al2O3 and Al3Ti. High resolution TEM showed that the α-Al2O3 dispersoids exhibited some lattice matching with the α-Al matrix. Coalescence of the block-shaped Al2O3 dispersoids occurred after heat treatment, and Al4C3 also became attached to them. The length and width of the block-shaped Al2O3 dispersoids increased by a factor of ∼1.55 between 340 and 1500 hours at 600 °C. 相似文献
15.
U. Kamachi Mudali N. Bhuvaneswaran P. Shankar H. S. Khatak B. Raj 《Metallurgical and Materials Transactions A》2004,35(6):1799-1806
This article presents the preparation, characterization, and hot-salt oxidation behavior of nitrogen-containing type 316L
stainless steel (SS), surface modified with intermetallic coatings. Three different types of intermetallic coating systems,
containing aluminum, titanium, and titanium/aluminum multilayers, were formed by diffusion annealing of type 316L austenitic
SS containing 0.015, 0.1, 0.2, and 0.56 pct nitrogen. Analysis by using X-ray diffraction (XRD), scanning electron microscopy
(SEM), and secondary ion mass spectroscopy (SIMS) confirmed the formation of various intermetallic phases such as AIN, Al13Fe4, FeAl2, FeTi, Ti2N, and Ti3Al in the coatings. Hot salt oxidation behavior of the uncoated and surface-modified stainless steels was assessed by periodic
monitoring of the weight changes of NaCl salt-applied alloys kept in an air furnace at 1023 K up to 250 hours. The oxide scales
formed were examined by XRD and stereomicroscopy. Among the various surface modifications investigated in the present study,
the results indicate that the titanium-modified alloys show the best hot-salt oxidation resistance with the formation of an
adherent, protective, thin, and continuous oxide layer. Among the four N-containing alloys investigated, the titanium and
Ti/Al multilayer modified 0.56 pct N alloy showed the best hot-salt oxidation resistance as compared to uncoated alloys. The
slower corrosion kinetics and adherent scale morphology indicate that the surface-modified titanium intermetallic coatings
could provide high-temperature service applications up to 1073 K, particularly in chloride containing atmospheres, for austenitic
stainless steels. 相似文献
16.
17.
The Effect of Iron Content on the Iron-Containing Intermetallic Phases in a Cast 6060 Aluminum Alloy
L. Sweet S. M. Zhu S. X. Gao J. A. Taylor M. A. Easton 《Metallurgical and Materials Transactions A》2011,42(7):1737-1749
The effect of iron content, ranging from 0.1 to 0.5 wt pct, on the formation of Fe-containing intermetallic phases in a cast
6060 aluminum alloy was investigated. Various characterization techniques, including optical microscopy, scanning electron
microscopy (SEM), electron backscatter diffraction (EBSD), and transmission electron microscopy (TEM) were used to examine
the identity, morphology, and prevalence of the Fe-Al and Fe-Al-Si intermetallic phases. The predominant phase is found to
be β-Al5FeSi at lower Fe levels, but this is replaced by α-AlFeSi (bcc structure) with increasing Fe content. The Fe containing intermetallic phases observed are compared to those
predicted using the Scheil module of THERMO-CALC software, and the similarities and discrepancies are discussed. 相似文献
18.
M. M. Stupel F. Hornstein B. Z. Weiss M. Ron 《Metallurgical and Materials Transactions A》1976,7(4):689-693
The first stages in the sintering of Ti-9 pct Fe were studied with the aid of room temperature M?ssbauer spectroscopy and
X-ray diffractometry. At a sintering temperature of 800°C most of the αFe disappeared after ten hours, at 1000°C-after less
than 10 minutes. The first stages of the densification process are controlled by the disappearance of theαFe phase, which causes a decrease in density. Density increases again only after that phase has completely disappeared. Small
quantities of TiFe intermetallic as an intermediate phase were observed to form, which subsequently converted toβTi. These small quantities of the intermetallic as well as theαFe phase were discernible only by M?ssbauer spectroscopy, not by X-ray diffractometry. A model is presented to describe the
formation of transient intermediate phases characteristic of the sintering process.
This research was supported by the United States-Israel Binational Science Foundation. 相似文献
19.
The microstructure evolution of impulse atomized powders of Al-0.61 wt pct and Al-1.90 wt pct Fe compositions have been investigated
with a scanning electron microscope, transmission electron microscope, neutron diffraction, and backscattering electron diffraction
(EBSD). Both hypoeutectic and hypereutectic compositions demonstrated similar macrostructure (i.e., primary α-Al dendrites/cells with eutectic Al-Fe intermetallics decorated at the dendritic/cellular walls). Selected area electron
diffraction (SAED) analysis and SAED pattern simulation identified the eutectic Al-Fe intermetallic as AlmFe (m = 4.0-4.4). This is verified by neutron diffraction analysis. Cubic texture was observed by EBSD on the droplets with dendritic
growth direction close to 〈111〉. The possible reasons are discussed. 相似文献
20.
W. Khalifa F. H. Samuel J. E. Gruzleski 《Metallurgical and Materials Transactions A》2003,34(3):807-825
The iron intermetallics observed in six dilute Al-Si-Fe alloys were studied using thermal analysis, optical microscopy, and
image, scanning electron microscopy/energy dispersive X-ray, and electron probe microanalysis/wavelength dispersive spectroscopy
(EPMA/WDS) analyses. The alloys were solidified in two different molds, a preheated graphite mold (600 °C) and a cylindrical
metallic mold (at room temperature), to obtain slow (∼0.2 °C/s) and rapid (∼15 °C/s) cooling rates. The results show that
the volume fraction of iron intermetallics obtained increases with the increase in the amount of Fe and Si added, as well
as with the decrease in cooling rate. The low cooling rate produces larger-sized intermetallics, whereas the high cooling
rate results in a higher density of intermetallics. Iron addition alone is more effective than either Si or Fe+Si additions
in producing intermetallics. The alloy composition and cooling rate control the stability of the intermetallic phases: binary
Al-Fe phases predominate at low cooling rates and a high Fe:Si ratio; the β-Al5FeSi phase is dominant at a high Si content and low cooling rate; the α-iron intermetallics (e.g., α-Al8Fe2Si) exist between these two; while Si-rich ternary phases such as the δ-iron Al4FeSi2 intermetallic are stabilized at high cooling rates and Si contents of 0.9 wt pct and higher. Calculations of the solidification
paths representing segregations of Fe and Si to the liquid using the Scheil equation did not conform to the actual solidification
paths, due to the fact that solid diffusion is not taken into account in the equation. The theoretical models of Brody and
Flemings[44] and Clyne and Kurz[45] also fail to explain the observed departure from the Scheil behavior, because these models give less weight to the effect
of solid back-diffusion. An adjusted 500 °C metastable isothermal section of the Al-Si-Fe phase diagram has been proposed
(in place of the equilibrium one), which correctly predicts the intermetallic phases that occur in this part of the system
at low cooling rates (∼0.2 °C/s). 相似文献