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1.
A small addition of Al in the liquid Zn bath inhibits the Fe/Zn reactions during hot dip galvanizing of steel sheets. Although
it is well known that Al and Fe are tied up in an layer located at the interface between Fe and Zn, the effect of the galvanizing
parameters on the formation of this Al-rich interfacial layer is not. This study has been carried out to determine the effect
of the galvanizing parameters on the formation of this Al-rich layer. Five zinc baths containing 0.10, 0.12, 0.13, 0.16, and
0.18 wt pct Al were used to produce galvanized coatings of commercial ultra-low-carbon (ULC) steel substrate. Full inhibition
of the Fe/Zn reactions was achieved in baths with Al content above 0.15 wt pct. The Al-rich layer is isomorphous to Fe2Al5 crystals and the Fe/Al ratio is close to Fe2Al5 with large amounts of Zn present (22 to 28 wt pct). The morphology of the Al-rich layer is strongly related to the Al content
of the bath. Indeed, bath contents above 0.15 wt pct are associated with two sublayers of Fe2Al5 crystals, making up colonies of grains of similar crystallographic orientation and directly associated to the crystallographic
orientation of the steel grains. In baths with contents below 0.15 wt pct, the Al-rich layer has only one sublayer of crystals
and shows colonies of grains with similar orientation. Finally, the Fe2Al5 crystals have a strong crystallographic texture. X-ray diffraction (XRD) reveals that the (200) planes are parallel to the
surface of the substrate. 相似文献
2.
A study was conducted on the effect of a uniform oxide layer on the galvanizing reaction in 0.20 wt pct Al-Zn and pure Zn
baths at 450 °C. In the 0.20 wt pct Al-Zn bath, poor wettability of the oxide layer was observed. No significant liquid Zn
penetration of the oxide occurred and, therefore, attack of the steel substrate to form localized Fe-Zn growth did not occur.
It was found that the iron oxide acted as a physical barrier or inhibition layer in the pure Zn bath, similar to the Fe2Al5 inhibition layer that forms at the steel interface in Al-Zn baths. The inhibition effect of the oxide in the pure Zn bath
was temporary, since cracks and other macrodefects in the oxide acted as fast diffusion paths for Zn. Localized Fe-Zn growth
(outbursts) formed at the steel/coating interface, and the number of outbursts was generally inversely proportional to the
oxide layer thickness at constant immersion times. Increased immersion time for a constant oxide layer thickness led to an
increase in the number of outbursts. These results simulate the diffusion short circuit mechanisms for Fe2Al5 inhibition layer breakdown in Al-containing Zn baths. 相似文献
3.
Effect of substrate grain size on iron-zinc reaction kinetics during hot-dip galvanizing 总被引:3,自引:0,他引:3
In the galvanizing process, it has been proposed that the grain size of the substrate steel influences the Fe-Zn alloy phase
reaction kinetics and growth rate during immersion in the liquid Zn bath. Two grain sizes (nominally 15 and 85 μm) were developed in a decarburized low-carbon (0.005) steel and hot-dipped galvanized in 0.00 wt pct Al-Zn and 0.20 wt pct
Al-Zn baths to study the effect of substrate grain size on Fe-Zn phase formation. Uniform attack of the substrate steel occurred
in the 0.00 wt pct Al-Zn bath, since an Fe2Al5 inhibition layer did not form. No barrier to nucleation of the Fe-Zn phases exists in this Zn bath, and therefore, the substrate
steel grain size had no significant effect on the kinetics of phase growth for the gamma, delta, and zeta phase layers. In
the 0.20 wt pct Al-Zn bath, discontinuous Fe-Zn phase growth (outburst formation) occurred due to the initial formation of
the Fe-Al inhibition layer. The nucleation of the Fe-Zn phases was significantly retarded in this bath for the large (85 μm) substrate grain size. Whereas outbursts were found in the 15-μm grain size substrate after 10 seconds of immersion time, it required 1200 seconds to nucleate just a few outbursts in the
85-μm substrate. These results support the mechanism that Fe-Al inhibition layer breakdown occurs along fast diffusion paths for
Zn in the inhibition layer that correspond to the location of substrate steel grain boundaries where reaction with Fe can
occur. 相似文献
4.
Phosphorous was ion implanted on one surface of a large grain (10 to 20 mm) low-carbon steel sheet in order to study the effect
of surface segregation on the formation of Fe-Zn phases during galvanizing. Both an Al-free and a 0.20 wt pct Al-Zn bath at
450 °C were used in this investigation. It was found that P surface segregation did not affect the kinetics of Fe-Zn phase
growth for the total alloy layer or the individual Fe-Zn gamma, delta, and zeta phase alloy layers in the 0.00 wt pct Al-Zn
baths. In the 0.20 wt pct Al-Zn bath, the Fe2Al5 inhibition layer formed with kinetics, showing linear growth on both the P-ion implanted and non-P-ion implanted surfaces.
Fe-Zn phase growth only occurred after extended reaction times on both surfaces and was found to directly correspond to the
location of substrate grain boundary sites. These results indicate that P surface segregation does not affect the growth of
Fe-Zn phases or the Fe2Al5 inhibition layer. It was shown that in the 0.20 wt pct Al-Zn bath, substrate grain boundaries are the dominant steel substrate
structural feature that controls the kinetics of Fe-Zn alloy phase growth. 相似文献
5.
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
6.
7.
Xingbo Liu Ever Barbero Jing Xu Matthew Burris Keh-Minn Chang Vinod Sikka 《Metallurgical and Materials Transactions A》2005,36(8):2049-2058
Corrosion tests of 316L and two intermetallic compounds Fe3Al and FeCrSi in industrial Galvanizing (Zn-0.18Al), GALFAN (Zn-5Al), GALVALUME (Zn-55Al), and Aluminizing (Al-8Si) baths
and lab-scale static baths were conducted. In on-line tests in industrial hot-dip baths, 316L steel shows better corrosion
resistance than Fe3Al in Galvanizing, GALFAN, and GALVALUME baths. The corrosion resistance of 316L and Fe3Al is similar in Aluminizing bath. In static tests, FeCrSi shows the best corrosion resistance in pure Zn, Zn-55Al, and Al-8Si
baths. The corrosion resistance of 316L is better than that of Fe3Al. In Zn-5Al bath, 316L shows no thickness loss after the test. For the same bath composition, the corrosion rates of the
alloys in industrial baths are higher than those in static baths. Bath temperature and chemical composition play important
roles in corrosion and intermetallic layer formation. Increasing bath temperature accelerates the corrosion process and changes
the nature of intermetallic layers. A small amount of aluminum reduces the corrosion process by reducing the activity of Zn
and forming inhibition layer. However, after aluminum content reaches the critical point, the dominant corrosion process changes
from Zn-Fe reaction to Al-Fe reaction, and, consequently, the corrosion process accelerates by increasing aluminum content
in the bath. 相似文献
8.
Lawrence Cho Seok Jae Lee Myung Soo Kim Young Ha Kim Bruno C. De Cooman 《Metallurgical and Materials Transactions A》2013,44(1):362-371
The selective oxidation and reactive wetting of intercritically annealed Si-bearing CMnSi transformation-induced plasticity steels were investigated by high-resolution transmission electron microscopy. In a N2 + 10 pct H2 gas atmosphere with a dew point (DP) ranging from 213 K to 278 K (?60 °C to 5 °C), a continuous layer of selective oxides was formed on the surface. Annealing in a higher DP gas atmosphere resulted in a thinner layer of external oxidation and a greater depth of internal oxidation. The hot dipping was carried out in a Zn bath containing 0.22 mass pct Al, and the bath temperature was 733 K (460 °C). Coarse and discontinuous Fe2Al5?x Zn x grains and Fe-Zn intermetallics (?? and ??) were observed at the steel/coating interface after the hot dip galvanizing (HDG) of panels were annealed in a low DP atmosphere 213 K (?60 °C). The Fe-Zn intermetallics were formed both in areas where the Fe2Al5?x Zn x inhibition layer had not been formed and on top of non-stoichiometric Fe-Al-Zn crystals. Poor wetting was observed on panels annealed in a low DP atmosphere because of the formation of thick film-type oxides on the surface. After annealing in higher DP gas atmospheres, i.e., 263 K and 278 K (?10 °C and 5 °C), a continuous and fine-grained Fe2Al5?x Zn x layer was formed. No Fe-Zn intermetallics were formed. The small grain size of the inhibition layer was attributed to the nucleation of the Fe2Al5?x Zn x grains on small ferrite sub-surface grains and the presence of granular surface oxides. A high DP atmosphere can therefore significantly contribute to the decrease of Zn-coating defects on CMnSi TRIP steels processed in HDG lines. 相似文献
9.
Lawrence Cho Myung Soo Kim Young Ha Kim Bruno C. De Cooman 《Metallurgical and Materials Transactions A》2013,44(11):5081-5095
The Fe-Zn reaction occurring during the galvannealing of a Si-bearing transformation-induced plasticity (TRIP) steel was investigated by field-emission electron probe microanalysis and field-emission transmission electron microscopy. The galvannealing was simulated after hot dipping in a Zn bath containing 0.13 mass pct Al at 733 K (460 °C). The galvannealing temperature was in the range of 813 K to 843 K (540 °C to 570 °C). The kinetics and mechanism of the galvannealing reaction were strongly influenced by the gas atmosphere dew point (DP). After the galvannealing of a panel annealed in a N2+10 pct H2 gas atmosphere with low DPs [213 K and 243 K (?60 °C and ?30 °C)], the coating layer consisted of δ (FeZn10) and η (Zn) phase crystals. The Mn-Si compound oxides formed during intercritical annealing were present mostly at the steel/coating interface after the galvannealing. Galvannealing of a panel annealed in higher DP [263 K and 273 K, and 278 K (?10 °C, 0 °C, and +5 °C)] gas atmospheres resulted in a coating layer consisting of δ and Г (Fe3Zn10) phase crystals, and a thin layer of Г 1 (Fe11Zn40) phase crystals at the steel/coating interface. The Mn-Si oxides were distributed homogeneously throughout the galvannealed (GA) coating layer. When the surface oxide layer thickness on panels annealed in a high DP gas atmosphere was reduced, the Fe content at the GA coating surface increased. Annealing in a higher DP gas atmosphere improved the coating quality of the GA panels because a thinner layer of oxides was formed. A high DP atmosphere can therefore significantly contribute to the suppression of Zn-alloy coating defects on CMnSi TRIP steel processed in hot dip galvanizing lines. 相似文献
10.
A. K. Mukhopadhyay 《Metallurgical and Materials Transactions A》1998,29(3):979-987
The deleterious effects of Fe-bearing constituent particles on the fracture toughness of wrought Al alloys have been known.
Recent studies have shown that the presence of Fe-bearing constituent particles is also detrimental to the nature and growth
of the hard anodic oxide coating formed on such materials. The present study, using a combination of scanning electron microscopy
(SEM), transmission electron microscopy (TEM), and electron probe microanalysis (EPMA), was made to examine the influence
of the nature of the Fe-bearing particles on the hard anodizing behavior of AA 7075 extrusion products containing varying
amounts of Si, Mn, and Fe impurities. It was found that, in the alloy containing 0.25 wt pct Si, 0.27 wt pct Mn, and 0.25
wt pct Fe, the Fe-bearing constituent particles are based on the Al12(FeMn)3Si phase (bcc with a=1.260 nm). These particles survive the hard anodizing treatment, add resistance to the electrical path, causing a rapid rise
in the bath voltage with time, and cause a nonuniform growth of the anodic oxide film. In the materials containing 0.05 wt
pct Si, 0.04 wt pct Mn, and 0.18 wt pct Fe, on the other hand, the formation of the Al12(FeMn)3Si-based phase is suppressed, and two different Fe-bearing phases, based on Al-Fe-Cu-Mn (simple cubic with a=1.265 nm) and Al7Cu2Fe, respectively, form. Neither the Al-Fe-Cu-Mn-based phase nor the Al7Cu2Fe-based phase survive the hard anodizing treatment, and this results in a steady rise in the bath voltage with time and a
relatively uniform growth of the anodic oxide film. Consideration of the size of the Fe-bearing particles reveals that the
smaller the particle, the more uniform the growth of the anodic oxide film. 相似文献
11.
Chang Wook Lee Bruno Charles De Cooman 《Metallurgical and Materials Transactions A》2014,45(10):4499-4509
Press hardening is increasingly being used to produce ultra-high strength steel parts for passenger cars. Al-Si, Zn, and Zn-alloy coatings have been used to provide corrosion protection to press hardening steel grades. The use of coatings has drawbacks such as coating delamination or liquid metal-induced embrittlement. In the present work, the microstructural evolution of Al-Zn coating during press hardening was studied. The 55 wt pct Al-Zn coating can in principle provide both Al barrier protection and Zn cathodic protection to press hardened steel. During the heat treatment associated with the press hardening, the 55 wt pct Al-Zn alloy coating is converted to an intermetallic surface layer of Fe2Al5 and a FeAl intermetallic diffusion layer. The Zn is separated from both intermetallic compounds and accumulates at grain boundaries and at the surface. This Zn separation process is beneficial in terms of providing cathodic protection to Al-Zn coated press hardening steel. 相似文献
12.
The reaction between solid iron and liquid Al-Zn baths 总被引:1,自引:0,他引:1
J. H. Selverian A. R. Marder M. R. Notis 《Metallurgical and Materials Transactions A》1988,19(5):1193-1203
The reaction which occurred between iron panels and Al-Zn baths during hot dipping was investigated. Three baths were studied:
45Al-55Zn, 55Al-45Zn, and 75Al-25Zn (in wt pct) in the temperature range of 570 to 655 °C. The reaction between the iron panel
and the Al-Zn bath was very severe and in all cases the iron panel was totally consumed by the bath in less than two minutes.
The rapid attack of the iron panels by the Al-Zn baths was attributed to two separate causes depending on growth conditions.
First, in some panels the intermediate layer which formed between the iron panel and the molten bath was nonadherent. This
resulted in the direct contact of the molten bath with the iron panel at a nonequilibrium interface, which presented a large
driving force and little inhibition for the reaction. Second, in panels containing an adherent alloy layer, the layer had
channels of liquid Zn which extended from the molten bath to the iron panel. These channels allowed rapid transport of Zn
and Al to the iron panel which resulted in a very high reaction rate. The controlling step in the reaction between the iron
panel and molten Al-Zn bath was the diffusion rate of Al in the molten bath to the surface of the iron panel. The diffusion
coefficient of Al in the molten bath was found to be in the range of 1 × 10-5 to 5 × 10-5 cm2/s. Microstructural, electron microprobe, and X-ray diffraction data are presented to support the above-mentioned mechanisms
and conclusions. 相似文献
13.
Guangxin Wu Jieyu Zhang Qian Li Kuochih Chou Xiaochun Wu 《Metallurgical and Materials Transactions B》2012,43(1):198-205
The microstructure and thickness of 55 pct A1-Zn-1.6 pct Si-0.2 pct RE coatings during continuous hot-dip on Q235 steel were
investigated in this work. The experimental results revealed that the intermetallic layer was composed of the Fe2Al5, FeAl3, and α-FeAlSi phases. The results of thermodynamic calculations with Pandat software package (CompuTherm, LLC, Madison, WI) indicated
that FeAl3 and α(β)-FeAlSi phase precipitated during the period of temperature cooling, which was consistent with experimental result. Then,
the thickness of intermetallic layer was characterized. It was shown that the thickness of intermetallic layer decreased after
0.2 wt pct RE was added. Finally, a first-principles calculation was performed to interpret the effect mechanism of RE on
the thickness of intermetallic layer. The results indicated that La substitution in Fe2Al5 and FeAl3 phases could grab electronic charges from Al atoms and weaken the formation of Fe-Al compounds. 相似文献
14.
D. K. Mukhopadhyay C. Suryanarayana F. H. FROES 《Metallurgical and Materials Transactions A》1995,26(8):1939-1946
The structural evolution in mechanically alloyed binary aluminum-iron powder mixtures containing 1, 4, 7.3, 10.7, and 25 at.
pct Fe was investigated using X-ray diffraction (XRD) and electron microscopic techniques. The constitution (number and identity
of phases present), microstructure (crystal size, particle size), and transformation behavior of the powders on annealing
were studied. The solid solubility of Fe in Al has been extended up to at least 4.5 at. pct, which is close to that observed
using rapid solidification (RS) (4.4 at. pct), compared with the equilibrium value of 0.025 at. pct Fe at room temperature.
Nanometer-sized grains were observed in as-milled crystalline powders in all compositions. Increasing the ball-to-powder weight
ratio (BPR) resulted in a faster rate of decrease of crystal size. A fully amorphous phase was obtained in the Al-25 at. pct
Fe composition, and a mixed amorphous phase plus solid solution of Fe in Al was developed in the Al-10.7 at. pct Fe alloy,
agreeing well with the predictions made using the semiempirical Miedema model. Heat treatment of the mechanically alloyed
powders containing the supersaturated solid solution or the amorphous phase resulted in the formation of the Al3Fe intermetallic in all but the Al-25 at. pct Fe powders. In the Al-25 at. pct Fe powder, formation of nanocrystalline Al5Fe2 was observed directly by milling. Electron microscope studies of the shock-consolidated mechanically alloyed Al-10.7 and
25 at. pct Fe powders indicated that nanometer-sized grains were retained after compaction. 相似文献
15.
S. Marich 《Metallurgical and Materials Transactions B》1970,1(10):2953-2958
A study has been made of the thermal stability of microstructures within unidirectionally solidified ingots of the rod-like Fe?Fe1-xS eutectic. The ingots were heat treated at temperatures of up to 98.7 pct of the eutectic’s melting point for times of up to 500 hr. At the higher temperatures the iron rods broke-up and spheroidized; these processes were accompanied by diffusion and precipitation of iron at surfaces and grain boundaries of specimens. The greater termalinstability of the Fe?Fe1-xS eutectic compared with that of the Al?CuAl2 and Al?Al3Ni eutectics was attributed to the higher interfacial energy of the former system, the absence of preferred crystallographic orientations and the higher temperatures of heat treatment. 相似文献
16.
A. Sémoroz Ph.D. L. Strezov M. Rappaz 《Metallurgical and Materials Transactions A》2002,33(8):2695-2701
The crystallographic orientation of galvanized coatings (Zn-0.2Al-0.15Sb in wt pct) has been characterized by Electron-Backscattered
Diffraction (EBSD) and optical microscopy. While 80 pct of the nucleation spots in the coating give rise to single-crystal
Zn grains, it has been found that about 20 pct of them give rise to two or more orientation domains, each having a specific
crystallographic orientation. For such “polycrystalline Zn grains,” the orientations of the domains are crystallographically
related: they have a dense crystallographic direction (〈1010〉, 〈1120〉, or 〈0001〉) in common. Moreover, the crystallographic relationships are similar to those observed in snowflakes and can
be partially explained by the concept of a coincidence-site lattice (CSL). The EBSD measurements were also used in order to
measure quantitatively the crystallographic texture. In particular, it has been evidenced that the (0001) texture of galvanized
coatings is the result of two contributions: (1) the nuclei are preferentially oriented with the basal plane parallel to the
coating plane (33 pct of the grains have an angle between the basal plane and the coating plane smaller than 22.5 deg), and
(2) the grains having the basal plane parallel to the coating plane grow faster (these grains represent 43 pct of the coating
surface). This reinforcement of the texture during growth is in agreement with that predicted by growth models, which take
into account the effect of the interfaces. 相似文献
17.
The reaction mechanisms and the structures of the phases formed during the hot dipping of iron in 0 to 10 pct Al-Zn alloy
baths at temperatures of 450° to 700°C were studied by X-ray diffraction and electron microprobe analysis techniques. A new
mechanism for the inhibition reaction between iron and zinc is proposed. At bath temperatures below 600°C, a thin layer of
an Fe-Al-Zn ternary compound forms on the iron surface and inhibits the growth of Fe-Zn phases. Breakdown of inhibition occurs
during the dipping process when the ternary compound becomes rich in aluminum and transforms to a more stable structure which
is isomorphous with Fe2Al5. While this breakdown is occurring, the zinc atoms react with iron and form the conventional Fe-Zn phases.
In 1 to 10 pct Al-Zn baths at temperatures≥600°C a very violent, highly exothermic reaction occurs during hot dipping. This
type of process is due to the electronic bond rearrangements which occur during the formation of the intermetallic Fe2(AlZn)5. This intermetallic forms from the reaction of aluminum-bearing FeZn7 with the Zn-Al alloy bath. 相似文献
18.
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
19.
A. K. Mukhopadhyay 《Metallurgical and Materials Transactions A》1998,29(13):979-987
The deleterious effects of Fe-bearing constituent particles on the fracture toughness of wrought A1 alloys have been known.
Recent studies have shown that the presence of Fe-bearing, constituent particles is also determental to the nature and growth
of the hard anodic oxide coating formed on such materials. The present study, using a combination of scanning electron microscopy
(SEM), transmission electron microscopy (TEM), and electron probe microanalysis (EPMA), was made to examine the influence
of the nature of the Fe-bearing particles on the hard anodizing behavior of AA 7075 extrusion products containing varying
amounts of Si, Mn, and Fe impurities. It was found that, in the alloy containing 0.25 wt pct Si, 0.27 wt pct Mn, and 0.25
wt pct Fe, the Fe-bearing constituent particles are based on the Al12(FeMn)3Si phase (bcc with α=1.260 nm). These particles survive the hard anodizing treatment, add resistance to the electrical path,
causing a rapid rise in the bath voltage with time, and cause a nonuniform growth of the anodic oxide film. In the materials
containing 0.05 wt pct Si, 0.04 wt pct Mn, and 0.18 wt pct Fe, on the other hand, the formation of the Al12(FeMn)3Si-based phase is suppressed, and two different Fe-bearing phases, based on Al−Fe−Cu−Mn-based (simple cubic with a=1.265 nm) and Al7Cu2Fe, respectively form. Neither the Al−Fe−Cu−Mn-based phase nor the Al7Cu2Fe-based phase survive the hard anodizing treatment, and this results in a steady rise in the bath voltage with time and a
relatively uniform growth of the anodic oxide film. Consideration of the size of the Fe-bearing, particles reveals that the
smaller the particle, the more uniform the growth of the anodic oxide film. 相似文献
20.
Robert Hansson Peter C. Hayes Evgueni Jak 《Metallurgical and Materials Transactions B》2004,35(4):633-642
The phase equilibria in the Al-Fe-Zn-O system in the range 1250 °C to 1695 °C in air have been experimentally studied using
equilibration and quenching techniques followed by electron probe X-ray microanalysis. The phase diagram of the binary Al2O3-ZnO system and isothermal sections of the Al2O3-“Fe2O3”-ZnO system at 1250 °C, 1400 °C, and 1550 °C have been constructed and reported for the first time. The extents of solid
solutions in the corundum (Al,Fe)2O3, hematite (Fe,Al)2O3, Al2O3*Fe2O3 phase (Al,Fe)2O3, spinel (Al,Fe,Zn)O4, and zincite (Al,Zn,Fe)O primary phase fields have been measured. Corundum, hematite, and Al2O3*Fe2O3 phases dissolve less than 1 mol pct zinc oxide. The limiting compositions of Al2O3*Fe2O3 phase measured in this study at 1400 °C are slightly nonstoichiometric, containing more Al2O3 then previously reported. Spinel forms an extensive solid solution in the Al2O3-“Fe2O3”-ZnO system in air with increasing temperature. Zincite was found to dissolve up to 7 mole pct of aluminum in the presence
of iron at 1550 °C in air. A meta-stable Al2O3-rich phase of the approximate composition Al8FeZnO14+x
was observed at all of the conditions investigated. Aluminum dissolved in the zincite in the presence of iron appears to
suppress the transformation from a round to platelike morphology. 相似文献