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1.
2.
Jeonghyeon Do Hyuk-Joong Lee Changwoo Jeon Dae Jin Ha Choongnyun Paul Kim Byeong-Joo Lee Sunghak Lee Yang Su Shin 《Metallurgical and Materials Transactions A》2012,43(7):2237-2250
In the current study, Fe-based alloys were used for powder injection molding (PIM) parts with various qualities and hardness ranges by varying chemical compositions according to thermodynamically calculated phase diagrams. Their microstructure and hardness values were analyzed and compared with those of the PIM specimens made from conventional Fe-based alloy powders or stainless steel powders. The Cr-to-B ratio (X Cr/X B) and the sum of Fe, Cr, and B content (X Fe+X Cr+X B) were varied to design nine Fe-based alloy compositions based on the composition of Armacor ??M?? alloy powders (Liquidmetal Technologies, Lake Forest, CA). According to the microstructural analysis results of the cast and heat-treated Fe-based alloys, large amounts of (Cr,Fe)2B were formed in the tempered martensite matrix. The volume fraction of (Cr,Fe)2B was varied from 42?pct to 91?pct with alloy compositions, and these results were well matched with the thermodynamically calculated volume fractions of (Cr,Fe)2B. The hardness of the fabricated alloys was varied from 300?VHN to 1600?VHN with alloy compositions, and this value increased linearly with the increasing volume fraction of (Cr,Fe)2B. From the correlation data between the volume fraction of (Cr,Fe)2B and hardness, the high-temperature equilibrium phase diagram, which could be used for the design of Fe-based alloys with various fractions and hardness values of (Cr,Fe)2B, was made. 相似文献
3.
《Acta Metallurgica》1987,35(8):1981-1993
The effect of chromium and iron additions and of annealing and working on the microstructure and tensile properties of vapour quenched AlCr and AlCrFe alloys has been determined. Tensile strengths of the worked AlCrFe alloys were in the range 568–831 MPa. Chromium in solid solution or iron present as iron-rich precipitates increased the yield stress by 44.7 MPa/at.%Cr and 333 MPa/at.%Fe respectively. The contributions to the yield strength of AlCr alloys were solid solution 40% and dislocation density/cell size 60% and to the yield strength of AlCrFe alloys were solid solution 25%, iron-rich precipitates 42% and dislocation density/cell size 33%. Vapour quenching may allow the more efficient use of alloying elements in the strengthening of Al-alloys and greater flexibility in obtaining the desired combination of solute concentration, particle volume fraction and particle size. 相似文献
4.
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
5.
MicrostructureandRoomTemperatureTensilePropertiesofFe_3Al-basedAlloyswithCeriumAdditionZhangZhonghua(张忠铧),SunYangshan(孙扬善),Gu?.. 相似文献
6.
M. Hüller M. Wenderoth U. Glatzel R. Völkl S. Vorberg B. Fischer 《Metallurgical and Materials Transactions A》2005,36(3):681-689
The objective of this work was to produce an alloy showing a microstructure similar to Ni-base superalloys, but with Pt as
base metal. The Pt-base alloys with various contents of Al, Cr, and Ni were arc melted. Solution heat treatments at 1450 °C
followed by water quenching lead to single-phase alloys. Ageing at 1000 °C resulted in the precipitation of Ll2 ordered particles. An alloy with 11 at. pct Al, 3 at. pct Cr, 6 at. pct Ni, and Pt balance shows cuboidal precipitates with
edge lengths of 200 to 500 nm along with a volume fraction of 23 pct and a lattice misfit of −0.1 pct. Aging at 1100 °C leads
to coarsening of precipitates. Volume fraction and morphology of the precipitates were investigated by scanning electron microscopy
and optical microscopy. X-ray diffraction as well as transmission electron microscopy (TEM) were applied to verify the crystal
structure. 相似文献
7.
R. Banerjee P. C. Collins H. L. Fraser 《Metallurgical and Materials Transactions A》2002,33(7):2129-2138
Ti-Cr alloys have been laser deposited from powder feedstock consisting of a blend of elemental powders using the laser-engineered
net-shaping (LENS) process. The microstructure of the as-deposited Ti-Cr alloys primarily consists of a metastable bcc matrix
of β-Ti(Cr) with precipitates along the grain boundaries. The grain-boundary precipitates have been identified to be of three
types, essentially pure hcp Ti, an alloyed hcp phase designated α-Ti(Cr), and the C14 TiCr2 Laves phase. Initial stages of decomposition, visible within the β matrix, suggest a spinodal clustering process resulting in a fine dispersion of second phases. Diffraction studies have revealed
the presence of fine precipitates of α within the β matrix. The evidence for the precipitation of the metastable ω phase within the β matrix is not strong. The phase evolution in the LENS-deposited Ti-Cr alloy has been discussed in the context of rapid solidification
and the enthalpy of mixing of the elemental powders. 相似文献
8.
M. Wenderoth U. Glatzel R. Völkl L. A. Cornish R. Süss S. Vorberg B. Fischer 《Metallurgical and Materials Transactions A》2005,36(3):567-575
The objective of this work is to mimic the microstructure and strengthening mechanisms of Ni-based superalloys in a new group
of high-temperature alloys based on the system Pt-Al. The elements Cr and Ni were chosen as further alloying components. Having
a face-centered cubic (fcc) crystal structure with an Ll2-ordered and coherently embedded phase, these new alloys should increase creep and corrosion resistance beyond Ni-based superalloys.
After arc melting and heat treatment, the alloys were investigated by means of scanning electron microscopy (SEM) and X-ray
diffraction (XRD). In the aged condition, the alloy composition 13 at. pct Al, 3 at. pct Cr, 7 at. pct Ni, and balance Pt
showed the most promising microstructure with cubical precipitates, 30 pct precipitate volume fraction, and a lattice misfit
of about −0.1 pct at room temperature.
This article is based on a presentation made in the symposium entitled “Beyond Nickel-Base Superalloys,” which took place
March 14–18, 2004, at the TMS Spring meeting in Charlotte, NC, under the auspices of the SMD-Corrosion and Environmental Effects
Committee, the SMD-High Temperature Alloys Committee, the SMD-Mechanical Behavior of Materials Committee, and the SMD-Refractory
Metals Committee. 相似文献
9.
The effects of Cr additions to y-base alloys have been investigated, using bulk materials consolidated from rapid solidification-processed
ribbons. The composition ranges studied were 0 to 4 at. pet Cr and 44 to 54 at. pet Al. It was found that Cr additions do
not affect the deformation behavior of single-phase γ alloys. However, they significantly enhance the plasticity of Al-lean
duplex alloys which contain grains of single-phase γ and grains of lamellar γ/α2. Other Cr effects on microstructure, phase stability, site occupancy, and deformation sub-structures were characterized and
correlated to the observed mechanical behavior. It was concluded that the ductilization effect of Cr in duplex alloys is partially
due to the tendency of Cr to occupy Al lattice sites. Ductilization is also partially due to the ability of Cr to modify the
Al partitioning and, therefore, the thermal stability of transformed α2 laths. 相似文献
10.
M. Hüller M. Wenderoth S. Vorberg B. Fischer U. Glatzel R. Völkl 《Metallurgical and Materials Transactions A》2005,36(13):681-689
The objective of this work was to produce an alloy showing a microstructure similar to Ni-base superalloys, but with Pt as
base metal. The Pt-base alloys with various contents of Al, Cr, and Ni were are melted. Solution heat treatments at 1450 °C
followed by water quenching lead to single-phase alloys. Ageing at 1000 °C resulted in the precipitation of L12 ordered particles. An alloy with 11 at. pct Al, 3 at. pct Cr, 6 at. pct Ni, and Pt balance shows cuboidal precipitates with
edge lengths of 200 to 500 nm along with a volume fraction of 23 pct and a lattice misfit of −0.1 pct. Aging at 1100 °C leads
to coarsening of precipitates. Volume fraction and morphology of the precipitates were investigated by scanning electron microscopy
and optical microscopy. X-ray diffraction as well as transmission electron microscopy (TEM) were applied to verity the crystal
structure.
M. Huller, formerly with Metallic Materials, University Bayreuth, D-95440 Bayreuth, Germany 相似文献
11.
Daniel P. Abraham Sean M. McDeavitt Jangyul Park 《Metallurgical and Materials Transactions A》1996,27(8):2151-2159
Stainless steel-zirconium alloys have been developed at Argonne National Laboratory to contain radioactive metal isotopes
isolated from spent nuclear fuel. This article discusses the various phases that are formed in as-cast alloys of type 304
stainless steel and zirconium that contain up to 92 wt pct Zr. Microstructural characterization was performed by scanning
electron microscopy (SEM) and energy dispersive X-ray spectroscopy (EDS), and crystal structure information was obtained by
X-ray diffraction. Type 304SS-Zr alloys with 5 and 10 wt pct Zr have a three-phase microstructure—austenite, ferrite, and
the Laves intermetallic, Zr(Fe,Cr,Ni)2+x. whereas alloys with 15, 20, and 30 wt pct Zr contain only two phases—ferrite and Zr(Fe,Cr,Ni)2+x. Alloys with 45 to 67 wt pct Zr contain a mixture of Zr(Fe,Cr,Ni)2+x and Zr2(Ni,Fe), whereas alloys with 83 and 92 wt pct Zr contain three phases—α-Zr, Zr2(Ni,Fe), and Zr(Fe,Cr,Ni)2+x. Fe3Zr-type and Zr3Fe-type phases were not observed in the type 304SS-Zr alloys. The changes in alloy microstructure with zirconium content have
been correlated to the Fe-Zr binary phase diagram. 相似文献
12.
An overview of materials developments of iron aluminium alloys with strengthening precipitate phases is given. The discussion is focussed on recent studies on Fe‐Al‐based alloys with strengthening precipitates, such as κ‐phase Fe3AlCx, MC‐carbide and Laves phase. Alloys of the following alloy systems were investigated: Fe‐Al‐C, Fe‐Al‐Ta, Fe‐Al‐Ni, Fe‐Al‐Ti‐Nb, and Fe‐Al‐M‐C (M = Ti, V, Nb, Ta). The investigations were centred on microstructure, constitution, and mechanical properties of such Fe‐Al‐based alloys with Al contents ranging from 10 to 30 at. %. Mechanisms and problems are discussed and perspectives are outlined. 相似文献
13.
《Acta Metallurgica Materialia》1990,38(4):643-653
The microstructure and mechanical properties of three melt-spun NiCrAl alloy ribbons have been studied in the as-cast condition as well as after thermal treatments. The microstructure of the alloys is dendritic-microcellular in as-cast condition and phases present for 10 at.% Al and 30 at.% Al alloys are as is predicted by the equilibrium phase diagram. In the 20 at.% Al alloy, γ' has frozen in metastable form and partial ordering takes place during cooling in the solid state. After thermal treatments the ribbons generally maintain a refined microstructure; α phase precipitates are always found in β and γ' phases in 20 and 30 at.% Al alloys. The hardness of the alloys increases with aluminum content. The tensile strength at room temperature is related to the phases present in the material for each state of treatment. The alloys are brittle, a higher ductility always being obtained in the as-cast condition. 相似文献
14.
H. Zou G. M. Hood J. A. Roy R. J. Schultz 《Metallurgical and Materials Transactions A》1994,25(7):1359-1365
The formation and stability of Fe-rich precipitates in two α-Zr(Fe) single-crystal alloys with nominal compositions I, 50
parts per million by atom (ppma) Fe, and II, 650 ppma Fe, have been investigated. Optical microscopy, scanning electron microscopy
(SEM), and transmission electron microscopy (TEM) were used to examine the characteristics of Fe-rich precipitates. The SEM
and TEM micrographs showed that in as-grown alloy II, Zr2Fe precipitates were located at “stringers. ”Precipitates were not observed in as-grown alloy I. Annealing treatments below
700 °C, for alloy I, and 820 °C, for alloy II, resulted in the diffusion of excess Fe (above the α-phase solution limit) to
the free surface with the subsequent formation of Zr3Fe precipitates in both alloys. Dissolution of Zr3Fe surface precipitates of alloy I (annealing above the solvus) left precipitate-like features on the surfaces. Zr2Fe precipitates in as-grown alloy II were readily dissolved by β-phase annealing. 相似文献
15.
The solute distribution within and near the proeutectoid α plates which were isothermally formed from the β solid solution
in Ti-V, Cr, and Fe alloys was measured in a scanning transmission electron microscope (STEM) equipped with an energy dispersive
X-ray (EDX) analyzer. In the Ti-4.9 at. pct Cr and 5.1 at. pct Fe alloys in which all measurements were made above the calculated
To temperature (the maximum temperature at which the diffusionless β to α transformation can occur), the solute concentration
in the α plates was close to final equilibrium as long as the analyzed plates had grown to the sizes comparable to the STEM
spatial resolution (∼50 nm). In the Ti-5.4 at. pct V and 2.6 at. pct Fe alloys, the solute concentration in the α plates was
already close to equilibrium at very short reaction times at temperatures more than 100 °C below To. The ledgewise diffusion growth mechanism can roughly account for the thickening behavior of these plates, consistent with
the results of the composition analysis. In the Cr alloy, a microstructure resembling the lower bainite in steels, i.e., nonlamellar
distribution of TiCr2 particles in thick α plates, was formed by coalescence of solute-depleted thin α plates which were formed in aggregates (in
sheaves) at an earlier stage of growth.
This paper is based on a presentation made in the symposium “International Conference on Bainite” presented at the 1988 World
Materials Congress in Chicago, IL, on September 26 and 27, 1988, under the auspices of the ASM INTERNATIONAL Phase Transformations
Committee and the TMS Ferrous Metallurgy Committee. 相似文献
16.
The influence of Cr and N on the transformation temperatures of a Fe‐8%Mn alloy has been investigated by means of equilibrium thermodynamics and dilatometry. The addition of Cr and N resulted in the presence of ferrite or α'‐martensite at room temperature, with the microstructure transforming to a single phase austenitic microstructure with increasing temperature. Only high amounts of Cr or N in excess of 0.2% prevented the transformation to a single phase austenitic microstructure. The addition of alloying elements resulted in a decrease of the martensite start temperature Ms. The effect on the austenite start temperature As was smaller. The effect of thermal cycling resulted in a stabilization of the transformation temperatures. More cycles were required to reach stable phase transformation temperatures when N was added to Fe‐Mn‐Cr alloys. 相似文献
17.
Mateusz Kotkowiak Adam Piasecki Michał Kotkowiak Michał Kulka 《Transactions of the Indian Institute of Metals》2018,71(12):2919-2931
Aluminizing process is an important technology in which aluminum is introduced into the surface of base material. In this work, aluminized layers were produced by the pack cementation process on Inconel 600, Inconel 625 and Nimonic 90 nickel-based alloys. Powder mixture contained 80% of Al and 20% of Fe–Cr. Microstructure, hardness, chemical composition and heat resistance were investigated. The microstructure consisted of intermetallic phases near the surface, and below them, the solid solution was observed. The oxidation resistance at elevated temperature of alloys with the layer was compared with pure alloys. After 20-h annealing at 1000 °C, the phase analysis was carried out. On the Nimonic 90 with aluminized coatings, a lot of Cr2O3 and Al2O3 oxides were produced, whereas on the pure Nimonic 90, a lot of NiO oxides were observed. It was found that the best heat resistance was obtained for the layer produced on the Nimonic 90. 相似文献
18.
Kyung Sub Jung Sai Ramudu Meka Ralf E. Schacherl Ewald Bischoff Eric J. Mittemeijer 《Metallurgical and Materials Transactions A》2012,43(3):934-944
The microstructure of the nitrided zone of Fe-Ti-Cr alloys, containing a total of 0.30 at. pct (Ti + Cr) alloying elements,
with varying Ti/Cr atomic ratio (0.45, 0.87, and 1.90), was investigated by X-ray diffraction (XRD) and transmission electron
microscopy (TEM). The stable TiN and CrN nitrides did not precipitate after nitriding. Instead, ultrafine, metastable, mixed
Ti1–x
Cr
x
N nitride precipitates developed in the nitrided zone: The precipitates were of platelet morphology (length ≤30 nm and thickness
≤3 nm) and of cubic, rock-salt, crystal-structure type. The misfit strain around the nitride platelets in the ferrite matrix
increases with increasing Ti/Cr atomic ratio. As a consequence, most pronouncedly for the highest Ti/Cr atomic ratio, a tetragonally
distorted ferrite matrix surrounds the precipitates, as evidenced both by XRD and TEM. The amount of nitrogen taken up was
determined quantitatively by measuring the so-called nitrogen-absorption isotherms. It follows that the absorbed amount of
so-called excess nitrogen dissolved in the matrix and adsorbed at the nitride-platelet faces increases distinctly with increasing
Ti/Cr atomic ratio. The results were discussed in terms of the dependence of misfit strain on the Ti/Cr atomic ratio and the
higher chemical affinity of Ti for N than of Cr for N. 相似文献
19.
Shivkumar Khaple R. G. Baligidad Sambasiva Rao 《Transactions of the Indian Institute of Metals》2009,62(2):153-157
Effect of titanium and nickel on the structure and properties of Fe3Al intermetallic alloy containing about 1.0wt.% C have been investigated. The composition of the alloying element was substituted
for Iron. The alloys were prepared by melting commercial grade raw materials iron, aluminum, titanium or nickel in air induction
furnace with flux cover (AIMFC). Further these ingots were refined by electroslag refining (ESR) process. These ingots could
be successfully hot-worked using conventional hot-forging and hot-rolling techniques. The hot-worked material was sound and
free from cracks. ESR hot-rolled alloys were examined using optical microscopy, X-ray diffraction (XRD), scanning electron
micrograph (SEM) to understand the microstructure of these alloys. The electron probe micro analysis (EPMA) studies were carried
out to determine the matrix and precipitate compositions and to identify the phases present in the alloys. The base alloy
and the alloy containing Ni exhibited a two-phase microstructure of Fe3AlC0.5 precipitates in Fe3Al matrix. The alloy containing Ti exhibits three-phase microstructure, the additional phase being TiC precipitate. Ti addition
resulted in no improvement in strength at room temperature and at 873 K whereas Ni addition has resulted in greater improvement
in strength at room temperature and at 873 K and also improved the creep life significantly from 66 hrs to 111 hrs. 相似文献
20.
The laser surface cladding technique was used to formin situ Fe-Cr-Mn-C alloys on AISI 1016 steel substrate. In this process mixed powders containing Cr, Mn, and C with a ratio of 10∶1∶1
were delivered using a screw feed, gravity flow carrier gas aided system into the melt pool generated by a 10 kw CO2 laser. This technique produced ultrafine microstructure in the clad alloy. The microstructure of the laser surface clad region
was investigated by optical, scanning, and transmission electron microscopy and X-ray microanalysis techniques. Microstructural
study showed a high degree of grain refinement and an increase in solid solubility of alloying elements which, in turn, produced
a fine distribution of complex types of carbide precipitates in the ferrite matrix because of the high cooling rate. An alloy
of this composition does not show any martensitic or retained austenite phase. In preliminary wear studies the laser clad
Fe-Cr-Mn-C alloys exhibited far superior wear properties compared to Stellite 6 during block-on-cylinder tests. The improved
wear resistance is attributed to the fine distribution of metastable M6C carbides. 相似文献