EP1060279A4 - Composite d'aluminure de fer et procede de fabrication - Google Patents

Composite d'aluminure de fer et procede de fabrication

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Publication number
EP1060279A4
EP1060279A4 EP99905633A EP99905633A EP1060279A4 EP 1060279 A4 EP1060279 A4 EP 1060279A4 EP 99905633 A EP99905633 A EP 99905633A EP 99905633 A EP99905633 A EP 99905633A EP 1060279 A4 EP1060279 A4 EP 1060279A4
Authority
EP
European Patent Office
Prior art keywords
iron aluminide
composite
iron
powder
feal
Prior art date
Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
Withdrawn
Application number
EP99905633A
Other languages
German (de)
English (en)
Other versions
EP1060279A1 (fr
Inventor
Seetharama C Deevi
Joachim Hugo Schneibel
Current Assignee (The listed assignees may be inaccurate. Google has not performed a legal analysis and makes no representation or warranty as to the accuracy of the list.)
Chrysalis Technologies Inc
Original Assignee
Chrysalis Technologies Inc
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Publication date
Application filed by Chrysalis Technologies Inc filed Critical Chrysalis Technologies Inc
Publication of EP1060279A1 publication Critical patent/EP1060279A1/fr
Publication of EP1060279A4 publication Critical patent/EP1060279A4/fr
Withdrawn legal-status Critical Current

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Classifications

    • C—CHEMISTRY; METALLURGY
    • C22—METALLURGY; FERROUS OR NON-FERROUS ALLOYS; TREATMENT OF ALLOYS OR NON-FERROUS METALS
    • C22C—ALLOYS
    • C22C29/00—Alloys based on carbides, oxides, nitrides, borides, or silicides, e.g. cermets, or other metal compounds, e.g. oxynitrides, sulfides
    • C22C29/005—Alloys based on carbides, oxides, nitrides, borides, or silicides, e.g. cermets, or other metal compounds, e.g. oxynitrides, sulfides comprising a particular metallic binder
    • C—CHEMISTRY; METALLURGY
    • C22—METALLURGY; FERROUS OR NON-FERROUS ALLOYS; TREATMENT OF ALLOYS OR NON-FERROUS METALS
    • C22C—ALLOYS
    • C22C33/00—Making ferrous alloys
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B22—CASTING; POWDER METALLURGY
    • B22F—WORKING METALLIC POWDER; MANUFACTURE OF ARTICLES FROM METALLIC POWDER; MAKING METALLIC POWDER; APPARATUS OR DEVICES SPECIALLY ADAPTED FOR METALLIC POWDER
    • B22F3/00—Manufacture of workpieces or articles from metallic powder characterised by the manner of compacting or sintering; Apparatus specially adapted therefor ; Presses and furnaces
    • B22F3/23—Manufacture of workpieces or articles from metallic powder characterised by the manner of compacting or sintering; Apparatus specially adapted therefor ; Presses and furnaces involving a self-propagating high-temperature synthesis or reaction sintering step
    • C—CHEMISTRY; METALLURGY
    • C22—METALLURGY; FERROUS OR NON-FERROUS ALLOYS; TREATMENT OF ALLOYS OR NON-FERROUS METALS
    • C22C—ALLOYS
    • C22C1/00—Making non-ferrous alloys
    • C22C1/04—Making non-ferrous alloys by powder metallurgy
    • C22C1/045—Alloys based on refractory metals
    • C22C1/0458—Alloys based on titanium, zirconium or hafnium
    • C—CHEMISTRY; METALLURGY
    • C22—METALLURGY; FERROUS OR NON-FERROUS ALLOYS; TREATMENT OF ALLOYS OR NON-FERROUS METALS
    • C22C—ALLOYS
    • C22C14/00—Alloys based on titanium
    • C—CHEMISTRY; METALLURGY
    • C22—METALLURGY; FERROUS OR NON-FERROUS ALLOYS; TREATMENT OF ALLOYS OR NON-FERROUS METALS
    • C22C—ALLOYS
    • C22C32/00—Non-ferrous alloys containing at least 5% by weight but less than 50% by weight of oxides, carbides, borides, nitrides, silicides or other metal compounds, e.g. oxynitrides, sulfides, whether added as such or formed in situ
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B22—CASTING; POWDER METALLURGY
    • B22F—WORKING METALLIC POWDER; MANUFACTURE OF ARTICLES FROM METALLIC POWDER; MAKING METALLIC POWDER; APPARATUS OR DEVICES SPECIALLY ADAPTED FOR METALLIC POWDER
    • B22F2998/00—Supplementary information concerning processes or compositions relating to powder metallurgy
    • B22F2998/10—Processes characterised by the sequence of their steps

Definitions

  • the invention relates generally to iron aluminide composites and method of manufacture thereof.
  • Iron base alloys containing aluminum can have ordered and disordered body centered crystal structures.
  • iron aluminide alloys having intermetallic alloy compositions contain iron and aluminum in various atomic proportions such as FegAl, FeAl, FeAl 2 , FeAl 3 , and F ⁇ j Al j .
  • Fe 3 Al intermetallic iron aluminides having a body centered cubic ordered crystal structure are disclosed in U.S. Patent Nos. 5,320,802; 5,158,744; 5,024,109; and 4,961,903.
  • Such ordered crystal structures generally contain 25 to 40 atomic % Al and alloying additions such as Zr, B, Mo, C, Cr, V, Nb, Si and Y.
  • An iron aluminide alloy having a disordered body centered crystal structure is disclosed in U.S. Patent No. 5,238,645 wherein the alloy includes, in weight %,
  • heating element configurations can be found in commonly owned U.S. Patent Nos. 5,530,225 and 5,591,368.
  • Other examples of electrical resistance heating elements can be found in commonly owned U.S. Patent Nos. 5,060,671; 5,093,894; 5,146,934; 5,188,130; 5,224,498; 5,249,586; 5,322,075; 5,369,723; and 5,498,855.
  • the nitrogen-gas atomized powders had low levels of oxygen (130 ppm) and nitrogen (30 ppm). To make sheet, the powders were canned in mild steel and hot extruded at 1000°C to an area reduction ratio of 9:1. The extruded nitrogen-gas atomized powder had a grain size of 30 ⁇ . The steel can was removed and the bars were forged 50% at 1000°C, rolled 50% at 850°C and finish rolled 50% at 650°C to 0.76 mm sheet.
  • Oxide dispersion strengthened iron-base alloy powders are disclosed in U.S. Patent Nos. 4,391,634 and 5,032,190.
  • the '634 patent discloses Ti-free alloys containing 10-40% Cr, 1-10% Al and ⁇ 10% oxide dispersoid.
  • the '190 patent discloses a method of forming sheet from alloy MA 956 having 75% Fe, 20% Cr, 4.5% Al, 0.5% Ti and 0.5% Y 2 O 3 .
  • the article states that FeAl alloys were prepared having a B2 ordered crystal structure, an Al content ranging from 23 to 25 wt % (about 40 at %) and alloying additions of Zr, Cr, Ce, C, B and Y 2 O 3 .
  • the article states that the materials are candidates as structural materials in corrosive environments at high temperatures and will find use in thermal engines, compressor stages of jet engines, coal gasification plants and the petrochemical industry.
  • the FA-350 alloy includes, in atomic %, 35.8% Al, 0.2% Mo, 0.05% Zr and 0.13% C.
  • the invention provides an iron aluminide composite comprising iron aluminide, an oxide filler and an additive which improves metallurgical bonding of the oxide filler to the iron aluminide.
  • the oxide filler can comprise alumina, zirconia, yttria, rare earth oxide and/or beryllia.
  • the additive can comprise a refractory carbide such as TiC, HfC and/or ZrC.
  • a preferred ratio of oxide: additive is 1 to 3.
  • the composite can be used for various devices such as tool bits, structural components or electrical resistance heating elements in devices such as heaters.
  • the composite comprises a liquid phase sintered composite.
  • the iron aluminide preferably comprises a binary alloy of iron and aluminum or an alloy.
  • the iron aluminide alloy can comprise, in weight %, 14-32% Al, ⁇ 2.0% Ti, ⁇ 2.0% Si, ⁇ 30 % Ni, ⁇ 0.5 % Y, ⁇ 15 % Nb, ⁇ 1 % Ta, ⁇ 3% W, ⁇ 10% Cr, ⁇ 2.0% Mo, ⁇ 1 % Zr, ⁇ 1 % C and ⁇ 0.1 % B.
  • the oxide filler preferably comprises alumina which can be present in any desired amount such as ⁇ 40% .
  • the additive preferably comprises ⁇ 40% TiC.
  • the composite can be Cr- free, Mn-free, Si-free, and/or Ni-free.
  • the composite can include non-oxide filler ceramic particles such as SiC, Si 3 N 4 , AIN, etc.
  • Preferred iron aluminide alloys include 20.0-31.0% Al, 0.05-0.15% Zr, ⁇ 3% W, ⁇ 0.1 % B and 0.01-0.2% C; 14.0-20.0% Al, 0.3-1.5% Mo, 0.05-1.0% Zr, ⁇ 3% W and ⁇ 0.2% C, ⁇ 0.1 % B and ⁇ 2.0% Ti; and 20.0-31.0% Al, 0.3-0.5% Mo, 0.05-0.3% Zr, ⁇ 0.2% C, ⁇ 2% W, ⁇ 0.1% B and ⁇ 0.5% Y.
  • the electrical resistance heating element can be used for products such as heaters, toasters, igniters, heating elements, etc. wherein the composite has a room temperature resistivity of 80-400 ⁇ ⁇ • cm, preferably 90-200 ⁇ ⁇ • cm.
  • the composite preferably heats to 900 °C in less than 1 second when a voltage up to 10 volts and up to 6 amps is passed through the alloy.
  • the composite When heated in air to 1000°C for three hours, the composite preferably exhibits a weight gain of less than 4 % , more preferably less than 2 % .
  • the composite preferably exhibits thermal fatigue resistance of over 10,000 cycles without breaking when pulse heated from room temperature to 1000°C for 0.5 to 5 seconds.
  • the composite has a room temperature flexure strength of at least 300 MPa in the liquid phase sintered condition and at least 1000 MPa in the hot forged condition.
  • the invention also provides a powder metallurgical process of making an iron aluminide composite by forming a mixture of iron aluminide powder, oxide powder and an additive which promotes adhesion of the oxide powder to the iron aluminide, forming the powder mixture into a body and sintering the body.
  • the body can be formed by hot or cold pressing and the sintering can comprise solid state, partial liquid or liquid phase sintering.
  • the forming can be carried out by placing the powder in a metal can, sealing the metal can with the powder therein, and hot pressing or hot extruding the metal can.
  • the body can be made by liquid phase infiltration of an iron aluminide matrix into a mass of oxide filler particles.
  • the sintered body can be hot forged or subjected to other working steps such as cold working, extrusion, rolling, etc. If desired, the powder mixture can be cold pressed prior to sintering and/or annealed subsequent to sintering.
  • Figure 1 shows an X-ray diffraction pattern for an FeAl/Al ⁇ composite in accordance with the invention
  • Figure 2 shows an X-ray diffraction pattern for an FeAl/ZrOj composite in accordance with the invention
  • Figure 3 shows a scanning electron microscope image of an FeAl/ZrQ composite in accordance with the invention
  • Figure 4 shows exudation of FeAl during liquid phase sintering of an FeAl/AljO 3 composite which did not include a TiC additive in accordance with the invention
  • Figure 5 shows the effect of TiC on improving liquid infiltration of Al,O 3 of iron aluminide
  • Figure 6 shows a scanning electron microscope image of a polished section of an FeAl/TiC/Al 2 O 3 composite in accordance with the invention
  • Figure 7 shows a hot forged coupon of Fe-15TiC-15A ⁇ O 3 (vol. %) in accordance with the invention wherein the interior of the coupon is sound and some edge cracking is evident around the exterior of the coupon;
  • Figure 8 is an optical micrograph of a liquid phase sintered composite of FeAl- 16.5TiC-16.5Al 2 O 3 (vol. %) in accordance with the invention.
  • Figure 9 is an optical micrograph of a hot forged composite of FeAl-15TiC-15A ⁇ O 3 (vol. %) in accordance with the invention.
  • Figure 10 is a graph of stress versus crosshead displacement produced during a flexure stress test of a composite of FeAl-15TiC-15Al 2 ⁇ 3 (vol. %) in accordance with the invention.
  • Figure 11 is a graph of load versus crosshead displacement produced during a fracture toughness test of a composite of FeAl-15TiC-15Al 2 O 3 (vol. %) in accordance with the invention.
  • the present invention is directed to iron aluminide composites including iron aluminide, an oxide filler and an additive which improves metallurgical bonding of the oxide filler to the iron aluminide.
  • the iron aluminide can include an iron concentration ranging from 4 to 32% by weight (nominal) and the oxide filler can comprise one or more oxides such as alumina, zirconia, yttria, rare 8
  • the additive preferably comprises at least one refractory carbide, refractory nitride or refractory boride such as TiC, HfC, ZrC, TiN, HfN, ZrN, TiB 2 , HfB 2 and/or ZrB 2 .
  • the concentration of the alloying constituents used in forming the iron aluminide is expressed herein in nominal weight percent.
  • the nominal weight of the aluminum essentially corresponds to at least about 97% of the actual weight of the aluminum in the iron aluminide.
  • a nominal 18.46 wt % may provide an actual 18.27 wt % of aluminum, which is about 99% of the nominal concentration.
  • the iron aluminide can be processed or alloyed with one or more selected alloying elements for improving properties such as strength, room-temperature ductility, oxidation resistance, aqueous corrosion resistance, pitting resistance, thermal fatigue resistance, electrical resistivity, high temperature sag or creep resistance and resistance to weight gain.
  • the iron aluminide composite can be used to make heating elements for various devices such as described in commonly owned U.S. Patent No. 5,530,225 or 5,591,368.
  • the composite can be used for other purposes such as in thermal spray applications wherein the composite could be used as coatings having oxidation and corrosion resistance.
  • the composite can be used as oxidation and corrosion resistant electrodes, furnace components, chemical reactors, sulfidization resistant materials, corrosion resistant materials for use in the chemical industry, pipe for conveying coal slurry or coal tar, substrate materials for catalytic converters, exhaust pipes for automotive engines, porous filters, etc.
  • the resistivity of the heater material can be varied by adjusting the iron aluminide alloy composition and/or the amount and/or type of filler material in the composite.
  • the composite can optionally include filler such as ceramic particles to enhance creep resistance and/or thermal conductivity.
  • the composite may also incorporate particles of electrically insulating material for purposes of making the composite creep resistant at high temperature and also enhancing thermal conductivity and/or reducing the thermal coefficient of expansion of the composite.
  • the electrically insulating/conductive particles/fibers can be added to a powder mixture of Fe, Al or iron aluminide or such particles/fibers can be formed by reaction synthesis of elemental powders which react exothermically during manufacture of the composite.
  • the composite can be made in various ways.
  • the iron alumimde of the composite can be made from a prealloyed powder or by mechanically alloying the alloy constituents.
  • the mechanically alloyed powder can be processed by conventional powder metallurgical techniques such as by canning and extruding, slip casting, centrifugal casting, hot pressing and hot isostatic pressing. Another technique is to use pure elemental powders of Fe, Al and optional alloying elements and mechanically alloying such ingredients.
  • the above mentioned electrically insulating and/or electrically conductive particles can be incorporated in the powder mixture to tailor physical properties and high temperature creep resistance of the composite.
  • the composite is preferably made by powder metallurgy techniques.
  • the composite can be produced from a mixture of powder having different fractions but a preferred powder mixture comprises particles having a size smaller than minus 100 mesh.
  • the iron aluminide powder can be produced by gas atomization in which case the powder may have a spherical morphology.
  • the iron aluminide powder can be made by water atomization in which case the powder may have an irregular morphology.
  • the iron aluminide powder produced by water atomization can include an aluminum oxide coating on the powder particles and such aluminum oxide can be broken up and incorporated in the composite during thermomechanical processing of the powder to form shapes such as sheet, bar, etc.
  • the alumina particles are effective in increasing resistivity of the iron aluminum 10
  • molybdenum When molybdenum is used as one of the alloying constituents of the iron aluminide it can be added in an effective range from more than incidental impurities up to about 5.0% with the effective amount being sufficient to promote solid solution hardening of the iron aluminide alloy and resistance to creep of the alloy when exposed to high temperatures.
  • concentration of the molybdenum can range from 0.25 to 4.25% and in one preferred embodiment is in the range of about 0.3 to 0.5% .
  • Titanium can be added to the iron alumimde in an amount effective to improve creep strength of the iron aluminide alloy and can be present in amounts up to 3 % .
  • the concentration of titanium is preferably in the range of ⁇ 2.0%.
  • the carbon is present in an effective amount ranging from more than incidental impurities up to about
  • the carbide former is present in an effective amount ranging from more than incidental impurities up to about 1.0% or more.
  • the carbon concentration is preferably in the range of about 0.03 % to about 0.3 % .
  • the effective amount of the carbon and the carbide former are each sufficient to together provide for the formation of sufficient carbides to control grain growth in the iron aluminide alloy during exposure thereof to increasing temperatures.
  • the carbides may also provide some precipitation strengthening in the iron aluminide alloy.
  • the concentration of the carbon and the carbide former in the iron aluminide alloy can be such that the carbide addition provides a stoichiometric or near stoichiometric ratio of carbon to carbide former so that essentially no excess carbon will remain in the finished alloy.
  • Zirconium can be incorporated in the iron aluminide alloy to improve high temperature oxidation resistance. If carbon is present, an excess of a carbide former such as zirconium in the iron aluminide alloy is beneficial in as much as it will help form a 11
  • the carbide formers include such carbide-forming elements as tungsten, titanium, zirconium, niobium, tantalum and hafnium and combinations thereof.
  • the carbide former is preferably in a concentration sufficient for forming carbides with the carbon present within the iron alumimde alloy.
  • concentrations for tungsten, niobium, tantalum, titanium, zirconium and hafnium when used as carbide formers can be present in amounts up to 3 wt % each.
  • the use of an effective amount of a rare earth element such as about 0.05-0.25% cerium or yttrium in the iron aluminide alloy composition is beneficial since it has been found that such elements improve oxidation resistance of the alloy.
  • the oxide filler can be in the form of particles such as powder, fibers, etc.
  • the composite can include up to 40 wt % of oxide particles such as Y 2 O 3 , Al 2 O 3 , rare earth oxide, beryllia or combinations thereof.
  • the oxide particles can be added to a melt or powder mixture of Fe, Al and other alloying elements.
  • the oxide can be created in situ by water atomizing a melt of an aluminum-containing iron-based alloy whereby a coating of alumina or yttria on iron-aluminum powder is obtained. During processing of the powder, the oxides break up and are arranged as stringers in the final product. Incorporation of the oxide particles in the iron aluminide alloy is effective in increasing the resistivity of the alloy. For instance, by incorporating about 0.5-0.6 wt % oxygen in the alloy, the resistivity can be raised from around 100 ⁇ ⁇ • cm to about 160 ⁇ ⁇ • cm.
  • the additive for promoting bonding between the iron aluminide and oxide filler can comprise any element or compound which improves wetting of the iron aluminide, i.e. lowers surface tension and/or contact angle.
  • the additive can comprise a 12
  • a preferred additive is a refractory carbide such as TiC, HfC and/or ZrC.
  • a refractory carbide such as TiC, HfC and/or ZrC.
  • the refractory carbide remains solid and promotes bonding of the oxide filler to the molten iron aluminide matrix.
  • particles of electrically conductive and/or electrically insulating metal compounds can be incorporated in the alloy.
  • Such metal compounds include oxides, nitrides, suicides, borides and carbides of elements selected from groups IVb, Vb and VIb of the periodic table.
  • the carbides can include carbides of Zr, Ta, Ti, Si, B, etc.
  • the borides can include borides of Zr, Ta, Ti, Mo, etc.
  • the suicides can include suicides of Mg, Ca, Ti, V, Cr, Mn, Zr, Nb, Mo, Ta, W, etc.
  • the nitrides can include nitrides of Al, Si, Ti, Zr, etc.
  • the oxides can include oxides of Y, Al, Si, Ti, Zr, etc.
  • Additional elements which can be added to the iron aluminide alloy include Si, Ni and B.
  • Si silicon up to 2.0% can improve low and high temperature strength but room temperature and high temperature ductility of the alloy may be adversely affected with additions of Si above 0.25 wt % .
  • the addition of up to 30 wt % Ni can improve strength of the iron aluminide alloy via second phase strengthening but Ni adds to the cost of the alloy and can reduce room and high temperature ductility thus leading to fabrication difficulties particularly at high temperatures.
  • Small amounts of B can improve ductility of the alloy and B can be used in combination with Ti and/or Zr to provide titanium and/or zirconium boride precipitates for grain refinement.
  • FeAl-based composites reinforced with insulating oxide filler can be prepared by a variety of techniques including conventional casting and powder metallurgical processes.
  • fabrication of iron aluminide-oxide composites was carried out using powder metallurgical techniques.
  • iron aluminide composites were prepared using A ⁇ O 3 and/or ZrO 2 as the oxide particulates.
  • ZrO 2 in particular, exhibits a high coefficient of thermal expansion, and has therefore a relatively small thermal mismatch with the iron aluminide matrix.
  • the composites were made by hot-pressing as well as low-cost techniques such as liquid phase sintering.
  • % Al 2 O 3 composites improved the room temperature flexure strength more than threefold. For instance, room temperature flexure strengths exceeding 1000 MPa can be obtained with the hot-forged composites. Such improvement in mechanical properties mat be due to reduction in residual porosity in the composites.
  • a dramatic improvement of the liquid phase sintering behavior can be obtained by incorporating an additive (e.g., TiC) which promotes wetting of the oxide filler.
  • FeAl/Al 2 O 3 and FeAl/ZrO 2 specimens prepared by mixing Fe-40 at. % Al, Al 2 O 3 or Y 2 O 3 -stabilized ZrO 2 powders and liquid phase sintering them in vacuum at 1450°C or 1500°C.
  • FeAl is intended to denote Fe-40 at. % Al.
  • FeAl/ZrO 2 composite included cubic stabilized ZrO 2 as well as FeAl. However, there was also evidence of substantial amounts of alpha alumina suggesting a displacement reaction of the type: 3 ZrO 2 + 24 FeAl ⁇ 2 Fe ⁇ Al + 3 Fe 6 Al 6 Zr + 2 Al 2 O 3 , where Fe 6 Al 6 Zr is a 14
  • a hot-pressed FeAl/ZrO 2 specimen including 10% Al 2 O 3 and 10% ZrO 2 was tested to determine flexure strength.
  • Optical microscopy of the sample revealed that a reaction occurred in the material and chipped edges of flexure bars ground from the material indicated that the material was brittle in nature.
  • the flexure bars fractured in a brittle manner indicating that the iron alumimde had reacted to form more brittle phases.
  • the material exhibited a room temperature flexure strength of 215 + 29 MPa.
  • ZrO 2 is not thermodynamically stable in contact with FeAl.
  • prealloyed iron aluminide powders were mixed with oxide powders.
  • the powder mixtures were then poured into alumina crucibles which were covered with an alumina lid. In most cases, the crucibles had an inner diameter and inner height of 38 mm and 8 mm, respectively. Although the powder mixtures were not cold pressed prior to sintering, cold pressing prior to sintering is expected to improve the fabricability significantly.
  • the filled crucibles were usually pumped overnight to an indicated vacuum better than 10-5 Torr. Subsequently, the specimen was ramped to 1450 or 1500°C over a period of 2 h, held for 0.2 to 0.3 h at that temperature, followed by furnace cooling. At 1450 or 1500°C, the iron aluminide melted and liquid phase sintering occurred.
  • Figures 1 and 2 show powder X-ray diffraction patterns for specimens A003 (FeAl/Al 2 O 3 ) and A004 (FeAl/ZrO 2 ). Consistent with thermodynamic stability, the 15
  • the diffraction pattern for the FeAl/Al 2 O 3 composite indicates mostly ⁇ -Al 2 O 3 and FeAl. Two small peaks at 21 and 30° could not be identified.
  • the diffraction pattern for the FeAl/ZrO 2 composite indicates cubic stabilized ZrO 2 as well as FeAl. However, there is evidence for substantial amounts of ⁇ -alumina suggesting a displacement reaction of the type:
  • Al 2 O 3 was found to be a suitable reinforcement in iron aluminide cermets.
  • ZrO 2 on the other hand, was unstable in contact with liquid FeAl, and brittle Fe- Al-Zr intermetallics formed instead.
  • AJ ⁇ O 3 was poorly wetted by liquid iron aluminide.
  • additions of either Ti or C to the iron aluminide did not improve the wetting of the Al 2 O 3 .
  • the combined addition of Ti and C in the form of TiC particulates, improved the wettability dramatically and resulted in much denser coupons.
  • cold pressing of the powder mixtures can be used to reduce the porosity of the final product. Optimization can be achieved by conducting quantitative density and porosity measurements to determine the concentrations of alloying additions 17
  • A008 (Fe40Al-ll wt% Ti)/28 A032, A033., Liquid phase Porous wt% ZrO 2 A001 sintering with Ti pellet, addition exuded FeAl, Pellet electrically conductive
  • specimen A009 was fabricated from Fe-40 at. % Al powder (-325 mesh or ⁇ 45 m), TiC powder (2.5-4 ⁇ m), and Al 2 O 3 powder ( ⁇ 38 ⁇ m), the sample having a nominal composition of FeAl- 16.5 vol. % TiC- 16.5 vol. % AljO 3 .
  • Compositions and preparation techniques for specimen A009 and additional specimens are set forth in Table 3.
  • Specimen A062C was made from powders having the following sizes: l-5 m Fe, 10 ⁇ m Al, 2.5-4 ⁇ m TiC and ⁇ 38 ⁇ m Al 2 O 3 .
  • the liquid phase sintering was carried out as follows: 0.3 h in vacuum for specimen A009, 0.2 h in vacuum for specimen A046, 0.2 h in vacuum for specimen A047, 0.2 h in vacuum for specimen A050, and 0.2 h in vacuum for specimen A062C. Table 3.
  • Specimens with the nominal composition FeAl-16.5vol%TiC-16.5vol%Al 2 O 3 were also fabricated by cold-pressing and subsequent sintering for 12 minutes at 1500°C in vacuum. Similar results were achieved using prealloyed FeAl (specimen A046) or elemental Fe and Al powders (specimen A047). However, the composite fabricated from elemental powders may have a slightly lower porosity level. In specimen A050, elemental Nb was added to the composite with the expectation that Nb would bond well to the A ⁇ O 3 and improve fracture toughness.
  • Specimen A062C was made by mixing 60 g of Fe, Al, TiC and AJ ⁇ O 3 and liquid phase sintering the mixture in an Al,O 3 crucible to provide a FeAl-15TiC-15Al 2 O 3 (vol. %) composite.
  • the sintered cylinder was hot forged at 1000°C from a height of 20 mm to approximately 8mm.
  • the hot forged coupon is shown in Figure 7 wherein edge cracking can be seen around the periphery of the coupon and the interior of the coupon is sound.
  • Figure 8 is an optical micrograph of specimen A046 fabricated with prealloyed Fe40Al powder. The bright TiC particles, dark A ⁇ J O 3 particles, with black pores surrounded by gray iron aluminide matrix are clearly visible. Processing with elemental 25
  • Figure 9 shows the microstructure of a hot forged coupon (A062C) wherein there is an absence of porosity.
  • Specimens for room temperature flexure tests were prepared by grinding samples having a cross section of approximately 3x4 mm. The flexure tests were carried out with a span of 20 mm and a cross head speed of 10 m/s.
  • Hot forging resulted in a pronounced strength increase.
  • Figure 10 shows three stress displacement curves for bend bars machined from coupon A062C (FeAl-15TiC- 15Al 2 O 3 , vol. %). The curves demonstrate not only a high strength, but also a small amount of ductility.
  • the beneficial effect of the hot forging is attributed to the removal of porosity.
  • Some specimens were annealed for 1 day at 500 °C in order to remove thermal vacancies which were presumably frozen in during the hot forging.
  • the removal of excess vacancies in iron aluminides results in a reduction of the high yield strength and an increase in ductility.
  • the anneal was expected to reduce the flaw sensitivity and increase fracture strength, it was found that the anneal did not affect the fracture strength significantly.
  • the room temperature fracture toughness of the hot forged FeAl-lSTiC-lSA ⁇ O-, composite was determined from the controlled fracture of chevron-notched specimens.
  • Figure 11 shows a measured load-displacement curve.
  • V p is the volume fraction of the ceramic particles
  • E p and E m are the moduli of the ceramic phases (estimated to be 410 GPa) and the matrix (180 GPa).
  • the Young's modulus for FeAl-15TiC-15Al 2 O 3 (vol. %) is estimated to be 228 Gpa.

Abstract

La présente invention concerne un composite d'aluminure de fer comprenant une charge d'oxyde et un additif qui améliore la liaison métallurgique de la charge d'oxyde à l'aluminure de fer. Le composite de la présente invention est utilisé dans des composants structurels, des profilés extrudés et des éléments chauffants à résistance électrique. L'aluminure de fer peut comprendre, en pourcentage en poids, ≤1 % Cr, 4-32 % Al, ≤2 % Ti, ≤2 % Mo, ≤1 % Zr, ≤1 % C, ≤3 % W et ≤0,1 % B. La charge d'oxyde peut comprendre ≤40 % de particules d'oxyde d'aluminium et l'additif peut comprendre jusqu'à 40 % d'un ou plusieurs carbures réfractaires tels que le TiC.
EP99905633A 1998-02-02 1999-02-02 Composite d'aluminure de fer et procede de fabrication Withdrawn EP1060279A4 (fr)

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US1748398A 1998-02-02 1998-02-02
US17483 1998-02-02
PCT/US1999/002211 WO1999039016A1 (fr) 1998-02-02 1999-02-02 Composite d'aluminure de fer et procede de fabrication

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EP1060279A1 EP1060279A1 (fr) 2000-12-20
EP1060279A4 true EP1060279A4 (fr) 2003-02-12

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JP (1) JP2002501983A (fr)
KR (1) KR20010040578A (fr)
CN (1) CN1292039A (fr)
AU (1) AU2575499A (fr)
BR (1) BR9908525A (fr)
CA (1) CA2319507A1 (fr)
ID (1) ID27488A (fr)
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WO (1) WO1999039016A1 (fr)

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JP4852737B2 (ja) * 2004-09-27 2012-01-11 国立大学法人 千葉大学 リサイクル型Ｆｅ−Ａｌ複合材料の製造方法
CN103820691B (zh) * 2014-02-27 2015-11-11 西安石油大学 一种FeAl/TiC复合材料的常压烧结制备方法
JP6615108B2 (ja) * 2014-10-10 2019-12-04 国立研究開発法人産業技術総合研究所 高温耐酸化性のレアメタルフリー硬質焼結体およびその製造方法
CN106939383B (zh) * 2017-01-11 2018-05-29 苏州金江铜业有限公司 一种变形铍铝合金板增塑挤压成形制备方法
CN109097656A (zh) * 2017-06-21 2018-12-28 高佑君 一种难熔金属与氧化锆复合的高温耐火材料及其制备方法
CN107552804B (zh) * 2017-09-05 2019-04-26 北京科技大学 一种烧结型高通量换热管用的合金粉末的制备及使用方法

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Publication number Publication date
WO1999039016A1 (fr) 1999-08-05
JP2002501983A (ja) 2002-01-22
CN1292039A (zh) 2001-04-18
NO20003836D0 (no) 2000-07-26
BR9908525A (pt) 2000-11-28
ID27488A (id) 2001-04-12
KR20010040578A (ko) 2001-05-15
AU2575499A (en) 1999-08-16
CA2319507A1 (fr) 1999-08-05
NO20003836L (no) 2000-10-02
EP1060279A1 (fr) 2000-12-20

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