WO2009054074A1 - Procédé de production pour matériau composite à matrice métallique - Google Patents

Procédé de production pour matériau composite à matrice métallique Download PDF

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Publication number
WO2009054074A1
WO2009054074A1 PCT/JP2007/070983 JP2007070983W WO2009054074A1 WO 2009054074 A1 WO2009054074 A1 WO 2009054074A1 JP 2007070983 W JP2007070983 W JP 2007070983W WO 2009054074 A1 WO2009054074 A1 WO 2009054074A1
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WO
WIPO (PCT)
Prior art keywords
powder
aluminum
casing
rolling
metal
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Application number
PCT/JP2007/070983
Other languages
English (en)
Inventor
Hideki Suzuki
Toshiaki Yamazaki
Kazuto Sanada
Yuichi Tamaki
Hideki Honmou
Toshimasa Nishiyama
Original Assignee
Nippon Light Metal Company, Ltd.
Nikkeikin Aluminium Core Technology Company, Ltd.
Priority date (The priority date 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 date listed.)
Filing date
Publication date
Application filed by Nippon Light Metal Company, Ltd., Nikkeikin Aluminium Core Technology Company, Ltd. filed Critical Nippon Light Metal Company, Ltd.
Priority to PCT/JP2007/070983 priority Critical patent/WO2009054074A1/fr
Publication of WO2009054074A1 publication Critical patent/WO2009054074A1/fr

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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
    • 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
    • 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
    • B22F2999/00—Aspects linked to processes or compositions used in powder metallurgy

Definitions

  • the present invention generally relates to a production method for a metal matrix composite material. More specifically, the present invention relates to a production method for a metal matrix composite material excellent in properties, such as plastic workability, thermal conductivity, room-temperature or high-temperature strength, high stiffness, neutron absorption performance, wear resistance and low thermal expansibility.
  • the sintering process in the step (3) includes: a technique (A) of simply heating the compact; a technique (B) of pressing the compact at high temperatures, such as hot pressing; a technique (C) of sintering the compact through hot plastic working, such as hot extruding, hot forging or hot rolling; a technique (D) of pressing the compact while applying a pulse current thereto, i.e., subjecting the compact to so-called
  • pulse-current pressure sintering (as disclosed, for example, in JP 2001-329302A) ; and a technique (E) based on a combination of two or more of the techniques (A) to (D) .
  • technique (E) based on a combination of two or more of the techniques (A) to (D) .
  • International Publication No. WO 2006/070879 relates to a method of producing an aluminum matrix composite material, which comprises the steps of: (a) mixing an aluminum powder and a ceramic powder to prepare a mixed powder; (b) subjecting the mixed powder to pulse-current pressure sintering together with a metal sheet to form a cladded material where a sintered compact is cladded with the metal sheet; and (c) subjecting the cladded material to plastic working to obtain an aluminum matrix composite material.
  • aluminum means both pure aluminum and an aluminum alloy.
  • a method of producing a metal matrix composite material which comprises the steps of mixing a metal powder and a ceramic powder to prepare a mixed powder, packing the mixed powder into a hollow and flat-shaped metal casing, hermetically closing the metal casing filled with the mixed powder to prepare a pre-rolling assembly, preheating the pre-rolling assembly, and rolling the preheated assembly.
  • the pre-rolling assembly is formed by packing the mixed powder into the metal casing and hermetically closing the metal casing.
  • the pre-rolling assembly is formed in such a manner that the mixed powder, i.e., mixed fine particles, is sandwiched from above and below by two metal plates serving as top and bottom walls of the metal casing.
  • the pre-rolling assembly can be subjected to rolling to reliably form a cladded material in which a layer of the mixture of the metal powder and the ceramic powder is cladded from above and below by the metal plates.
  • the metal powder may be a powder of pure aluminum having a purity of 99.0% or more, or a powder of aluminum alloy comprising Al and 0.2 to 2 weight% of at least one selected from the group consisting of Mg, Si, Mn and Cr, wherein the ceramic powder is contained in an amount of 0.5 to 60 mass% with respect to 100 mass% of the mixed powder.
  • the ceramic powder i.e., ceramic particles
  • the ceramic powder to be added as a reinforcing material
  • the ceramic powder generally have extremely high hardness.
  • a metal powder containing a large amount of ceramic powder is sintered to form a sintered body, and the sintered body is subjected to rolling, in a conventional manner, ceramic particles in a surface of the sintered body are highly likely to act as a fracture origin leading to wrinkling or cracking in a plastic-worked product. This also involves a problem about accelerated wear of an extrusion die, a mill roll, a forging die, etc.
  • any sintering process such as pulse-current pressure sintering, is not included in the method of the present invention.
  • a surface of the pre-rolling assembly is free from ceramic particles causing wear of a rolling die or the like. This uniquely provides an advantage of being able to obtain a high-quality rolled product, as a first feature of the present invention.
  • the mixed powder comprising the ceramic powder and the metal powder is packed in the hollow casing to allow the pre-rolling assembly to be maintained in a predetermined shape required for the rolling.
  • top and bottom walls of the hollow casing can serve as the upper and lower metal plates for forming a cladded material.
  • a structure of a cladded material is obtained only by packing the mixed powder into the casing. This also facilitates simplifying the production process, as a third feature of the present invention.
  • the packing step further includes the sub-step of vibrating the casing to increase a density of the mixed powder to be packed into the casing.
  • a density of the mixed powder is increased to a value enough to allow the mixed powder to be maintained in a predetermined shape required for rolling. For example, it is necessary to increase a powder density up to 98% or more.
  • the mixed powder is directly subjected to rolling, in powder form.
  • a powder density to be maintained in a state after the mixed powder is packed in the casing is enough to be about 98% at a maximum.
  • a peripheral portion of the casing is surrounded by a reinforcing frame. That is, before rolling, an outer surface of the mixed powder is fully covered by a metal plate. This provides an advantage of being able to reliably prevent wrinkling or cracking from occurring in a top or lateral surface or an inside of a composite material obtained by the rolling.
  • FIG. 1 is a perspective view showing the structure of a casing for use in a method according to a first embodiment of the present invention.
  • FIG. 2A illustrates the structure of a reinforcing frame for use in the method according to the first embodiment.
  • FIG. 2B is a vertical cross sectional view showing the casing in which the mixed powder is packed therein.
  • FIG. 3 is a microscope photograph showing a region (100 times magnified) around a skin layer of a cladded material as an end product obtained through a method of the present invention.
  • FIG. 4 is a microscope photograph partly showing the region (400 times magnified) around the skin layer in FIG. 3.
  • FIG. 5 is a microscope photograph showing a region of an intermediate layer (100 times magnified) of the cladded material in FIG. 3.
  • FIG. 6 is a microscope photograph partly showing the region of the intermediate layer (400 times magnified) in FIG. 5.
  • FIG. 7 is a graph showing peeling between a skin layer and an intermediate layer, in connection with a shape ratio and a mill outlet-side temperature.
  • FIG. 8 is a perspective view showing the structure of a casing for use in a method according to a second embodiment of the present invention.
  • a method comprises the steps of: (a) mixing a metal powder and a ceramic powder to prepare a mixed powder; (b) packing the mixed powder into a hollow and flat-shaped metal casing; (c) hermetically closing the metal casing filled with the mixed powder to prepare a pre-rolling assembly; (d) preheating the pre-rolling assembly; and (e) rolling the preheated assembly to obtain a metal matrix composite (MMC) material.
  • MMC metal matrix composite
  • an aluminum powder serving as a matrix is made of an Al-Mg based alloy, specifically an aluminum alloy defined as A 1100 by JIS (or AA 1100 by A.A. ) . More specifically, the aluminum powder comprises 0.25 weight% or less of silicon (Si), 0.40 weight% or less of iron (Fe), 0.05 weight% or less of copper (Cu), 0.05 weight% or less of manganese (Mn), 0.05 weight% or less of magnesium (Mg), 0.05 weight% or less of chromium (Cr), 0.05 weight% or less of zinc (Zn), 0.05 weight% or less of vanadium (V) and 0.03 weight% or less of titanium (Ti) , with the remainder being aluminum (Al) and inevitable impurities .
  • the aluminum powder in the present invention is not limited to the above specific composition.
  • pure aluminum e.g., JIS 1050 or 1070
  • various types of aluminum alloys such as an Al-Cu based alloy (e.g., JIS 2017), an Al-Mg-Si based alloy (e.g., JIS 6061), an Al-Zn-Mg based alloy (e.g., JIS 7075) and an Al-Mn based alloy, may be used for the aluminum powder, independently or in the form of a combination of two or more of them.
  • the composition of the aluminum powder may be selectively determined in consideration of desired characteristics or properties, resistance to deformation during subsequent forming/rolling processes, an amount of ceramic powder to be mixed therewith, a raw material cost, etc.
  • a pure aluminum powder is advantageous in terms of a raw material cost.
  • the pure aluminum powder has a purity of 99.5% or more (a commercially available pure aluminum powder typically has a purity of 99.7% or more) .
  • a boron compound is used for an after-mentioned ceramic powder.
  • At least one element having neutron absorption capability such as hafnium (Hf) , samarium (Sm) or gadolinium (Gd) , may be added to the aluminum powder, preferably in an amount of 0.1 to 50 mass%.
  • the aluminum powder may be added with at least one selected from the group consisting of titanium (Ti) , vanadium (V) , chromium (Cr) , manganese (Mn) , magnesium (Mg) , iron (Fe) , copper (Cu) , nickel (Ni) , molybdenum (Mo) , niobium (Nb) , zirconium (Zr) and strontium (Sr) .
  • the aluminum powder may be added with at least one selected from the group consisting of silicon (Si), iron (Fe), copper (Cu), magnesium (Mg) and zinc (Zn) .
  • each of the above elements may be added in an amount of 7 weight% or less, and two or more of the above elements may be added in a total amount of 15 mass% or less.
  • an average particle size of the aluminum powder is not limited to a specific value, an upper limit of the average particle size may be typically set at 200 ⁇ m or less, preferably 100 ⁇ m or less, more preferably 30 ⁇ m or less. A lower limit of the average particle size may also be freely determined in consideration of manufacturability, and may be typically set at 0.5 ⁇ m or more, preferably 10 ⁇ m or more.
  • a particle size distribution of the aluminum powder may be set at 100 ⁇ m or less, and an average particle size of the after- mentioned ceramic powder serving as a reinforcing material may be set at 40 ⁇ m or less. In this case, the reinforcing particles are uniformly dispersed over the aluminum powder to significantly reduce a low density region of the mixed powder so as to effectively provide stable properties to the MMC plate.
  • An excessive difference between respective average particle sizes of the aluminum powder and the after-mentioned ceramic powder is likely to cause wrinkling or cracking during rolling.
  • An excessively large average particle size of the aluminum powder causes difficulty in being uniformly mixed with the after-mentioned ceramic powder having a restriction on increasing an average particle size.
  • an excessively small average particle size of the aluminum powder is likely to cause aggregation of the aluminum fine particles, which leads to significant difficulty in being uniformly mixed with the after- mentioned ceramic powder.
  • the aluminum powder having an average particle size set in the above preferable range can provide further enhanced plastic workability/ formability and mechanical properties to the pre-rolling assembly.
  • An average particle size of the aluminum powder in the present invention is expressed by a value based on a laser- diffraction particle-size-distribution measurement method.
  • a particle shape of the aluminum powder is not limited to a specific one.
  • the aluminum powder may have a teardrop shape, a perfect spherical shape, a spheroidal shape, a flake shape or an amorphous shape, without any problems.
  • a production method for the aluminum powder is not limited to a specific one.
  • the aluminum powder may be prepared by any conventional metal powder production method.
  • the conventional method may include an atomization process, a melt spinning process, a rotating disk process, a rotating electrode process, and other rapid solidification processes.
  • the atomization process particularly a gas atomization process of atomizing molten metal to produce fine particles .
  • the molten metal is subjected to the atomization process while being heated at a temperature ranging from 700 to 1200 "C, because atomization of the molten metal can be effectively achieved when a temperature of the molten metal is set in the above range.
  • An atomizing medium may be air, nitrogen, argon, helium, carbon dioxide or water, or a mixed gas thereof. In view of economic efficiency, air, nitrogen gas or argon gas is preferable as the atomizing medium.
  • a ceramic material to be mixed with the aluminum powder so as to form the mixed powder includes AI2O3, SiC, B 4 C, BN, aluminum nitride and silicon nitride. These ceramic materials may be used in powder form, independently or in the form of a mixture of two or more of them, and may be selected depending on an intended purpose of an aluminum matrix composite material.
  • a boron-based ceramic powder is used, an aluminum matrix composite material to be obtained can be used as a neutron- absorbing material, because boron (B) has neutron absorption capability.
  • a boron-based ceramic material may include B4C, TiB2, B2O3, FeB and FeB ⁇ .
  • boron-based ceramic materials may be used in powder form, independently or in the form of a mixture of two or more of them.
  • B4C boron carbide
  • 1OB is the isotope of B and capable of excellently absorbing neutrons .
  • the ceramic powder is contained in the aforementioned aluminum powder preferably in an amount of 0.5 to 90 mass%, more preferably 5 to 60 mass%, particularly preferably 5 to 45 mass%.
  • the reason for the lower limit set at 0.5 mass% is that, if the content of ceramic powder becomes less than 0.5 mass%, an aluminum matrix composite material cannot be adequately reinforced.
  • the reason for the upper limit set at 90 mass% is that, if the content of ceramic powder becomes greater than 90 mass%, an aluminum matrix composite material will have difficulty in plastic working due to increased resistance to deformation, and a compact therein will be likely to fracture due to a brittle structure. Moreover, a bonding between aluminum particles and ceramic particles will deteriorate, and thereby the compact is highly likely to have voids therein to cause difficulty in obtaining intended functions and deterioration in thermal conductivity. Further, a cutting performance of the aluminum matrix composite material will deteriorate.
  • the ceramic powder such as a B4C or AI2O3 powder, may have any average particle size. Preferably, the average particle size of the ceramic powder is set in the range of 1 to 30 ⁇ m.
  • the average particle size of the ceramic powder is more preferably set in the range of 5 to 20 ⁇ m. If the average particle size of the ceramic powder becomes greater than 20 ⁇ m, an aluminum matrix composite material will have a problem that saw teeth are rapidly worn during cutting. If the average particle size of the ceramic powder becomes less than 5 ⁇ m, aggregation of fine ceramic particles is highly likely to occur to cause difficulty in being uniformly mixed with the aluminum powder.
  • An average particle size of the ceramic powder in the present invention is expressed by a value based on a laser- diffraction particle-size-distribution measurement method.
  • a particle shape of the ceramic powder is not limited to a specific one.
  • the ceramic powder may have a teardrop shape, a perfect spherical shape, a spheroidal shape, a flake shape or an amorphous shape.
  • Each of a metal casing, upper and lower casings, a casing body and a plug member (hereinafter referred to collectively as "casing") for use in the method of the present invention may be made of any metal capable of being adequately bonded with the mixed powder.
  • the casing is made of aluminum or stainless steel.
  • pure aluminum e.g., JIS 1050 or 1070
  • JIS 1050 or 1070 is usually used.
  • various types of aluminum alloys such as an Al- Cu based alloy (e.g., JIS 2017), an Al-Mg based alloy (e.g., JIS 5052), an Al-Mg-Si based alloy (e.g., JIS 6061), an Al-Zn-Mg based alloy (e.g., JIS 7075) and an Al-Mn based alloy, may be used for the casing.
  • a composition of the aluminum may be selectively determined in consideration of desired characteristics or properties, cost, etc. For example, in view of obtaining enhanced plastic workability/ formability and heat radiation performance, it is preferable to select pure aluminum. As compared with aluminum alloys, pure aluminum is advantageous in terms of a raw material cost.
  • an Al-Mg based alloy e.g., JIS 5052
  • at least one element having neutron absorption capability such as Hf, Sm or Gd, may be added to the aluminum.
  • the aluminum powder and a ceramic powder are prepared and uniformly mixed together.
  • the aluminum powder may be a single type, or may be a mixture of plural types of aluminum powders.
  • the ceramic powder may be a single type, or may be a mixture of plural types of ceramic powders, for example, a mixture of B4C and AI2O3 powders.
  • the aluminum powder and the ceramic powder may be mixed in a conventional manner using any type of mixer, such as a V blender or a cross rotary mixer or a drum blender; or a planetary mill, for a predetermined time (e.g., about 10 minutes to 10 hours) .
  • the mixing may be dry mixing or may be wet mixing. With a view to grinding during mixing, a grinding medium, such as alumina or SUS balls, may be appropriately added.
  • the mixed-powder preparation process consists only of the step of mixing the aluminum and ceramic powders to prepare a mixed powder, and the obtained mixed powder is sent to a next step.
  • a hollow and flat-shaped metal casing for packing the mixed powder prepared through the above mixed powder preparation process is prepared.
  • a lower casing 12 and an upper casing 14 are prepared to form the metal casing 10.
  • the lower casing 12 is made of aluminum, and formed in a shape which has opposed lateral walls 12A, 12B, a front wall 12C, a rear wall 12D and a bottom wall 12E, as shown in FIG. 1.
  • the upper casing 14 is made of aluminum, i.e., made of the same material as that of the lower casing 12, and formed in a shape which has opposed lateral walls 14A, 14B, a front wall 14C, a rear wall 14D and a top wall 14E, as shown in FIG. 1.
  • the lower casing 12 is formed in a rectangular parallelepiped shape which has a closed bottom and an open top
  • the upper casing 14 is formed in an approximately rectangular parallelepiped shape adapted to cover an outer peripheral surface of the lower casing 12 from above so as to serve as a closing member for closing the open top of the lower casing 12. That is, the upper casing 14 is formed to have a size slightly greater than that of the lower casing 12.
  • the posture of the casing 10 during rolling means a state when the casing 10 is positioned in such a manner that a longitudinal axis thereof (any central axis of the casing 19 when it has a square shape in top plan view) extends along a rolling direction and a surface thereof to be rolled extends along a horizontal direction.
  • the reinforcing frame 16 comprises first and second reinforcing members 16A, 16B adapted to be fixed to respective ones of the opposed lateral surfaces (walls) 14A, 14B of the upper casing 14 each parallel to the rolling direction, in such a manner as to extend along the rolling direction, and third and fourth reinforcing members 16C, 16D adapted to be fixed to respective ones of the front surface (wall) 14C and the rear surface (wall) 14D of the upper casing 14 each orthogonal to the rolling direction, in such a manner as to extend along a direction orthogonal to the rolling direction.
  • Each of the first and second reinforcing members 16A, 16B is formed to have a length allowing front and rear ends thereof located along the rolling direction to extend beyond respective ones of front and rear ends of a corresponding one of the lateral surfaces 14A, 14B of the upper casing 14, when the first and second reinforcing members 16A, 16B are fixed to the respective lateral surfaces 14A, 14B.
  • Each of the third and fourth reinforcing members 16C, 16D is formed to have a length equal to a length of a corresponding one of the front and rear surfaces 14C, 14D of the upper casing 14 in a direction orthogonal to the rolling direction, and is fixed with or secured to the first and second reinforcing members 16A, 16B 2-4: Packing Process
  • the mixed powder M prepared through the aforementioned mixed powder preparation process is packed into the lower casing 12.
  • This packing process is performed as an operation of feeding the mixed powder M at a constant feed rate.
  • an operation of tapping or mechanical compaction of the lower casing 12 is performed to increase a density of the mixed powder M to be packed.
  • a theoretical filling rate of the mixed powder M is set in the range of 35 to 65%.
  • the upper casing 14 is fitted onto the lower casing 12 from above to close the open top of the lower casing 12 so as to form a pre-rolling assembly 18 having the mixed powder M packed therein.
  • the reinforcing operation is performed by surrounding an outer peripheral surface, except top and bottom surfaces, of the pre-rolling assembly 18 in a posture during rolling by the reinforcing frame 16, as shown in FIG. 2B.
  • each of the first and second reinforcing members 16A, 16B is temporarily fixed to a corresponding one of the lateral surfaces 14A, 14B of the upper casing 14, in such a manner that opposite ends (i.e., the front and rear ends) thereof located along the rolling direction extends beyond respective ones of the front and rear ends of the corresponding one of the lateral surfaces 14A, 14B.
  • the third reinforcing member 16C is temporarily fixed to the front surface 14C of the upper casing 14, in such a manner that the opposite lateral ends thereof come into contact with the respective front ends of the first and second reinforcing members 16A, 16B
  • the fourth reinforcing member 16D is temporarily fixed to the rear surface 14D of the upper casing 14, in such a manner that opposite lateral ends thereof come into contact with the respective rear ends of the first and second reinforcing members 16A, 16B.
  • the pre-rolling assembly 18 having the reinforcing frame 16 temporarily fixed thereto is put in a vacuum furnace, and the vacuum furnace is depressurized to a predetermined degree of vacuum so as to subject the mixed powder M in the pre-rolling assembly 18 to degassing.
  • the temporarily fixed reinforcing frame 16 is finally fixed by MIG (metal inert gas) welding.
  • MIG metal inert gas
  • an upper edge of the reinforcing frame 16 is welded to an upper edge of the upper casing 14 all around, and a lower edge of the reinforcing frame 16 is welded to a lower edge of the upper casing 14 all around.
  • the lower edge of the upper casing 14 is located in a closely adjacent relation to a lower edge of the lower casing 12.
  • the lower edge of the reinforcing frame 16 is welded to the lower edge of the upper casing 14
  • the lower edge of the lower casing 12 is also welded to the respective lower edges of the reinforcing frame 16 and the upper casing 14, so that the casing 10 is gas-tightly sealed in its entirety, that is the mixed powder M is hermetically sealed in the casing 10.
  • first and second reinforcing members 16A and 16B for reinforcing the casing 10.
  • the third and fourth reinforcing members 16C and 16D along with the first and second reinforcing members 16A and 16B.
  • a gas vent hole (not shown) is formed at each of four corners of a top wall of the upper casing 14 to release air (and other gas) from the pre- rolling assembly 18 so as to prevent the air from remaining within the pre-rolling assembly 18. It can also be expected to allow gas getting into the pre-rolling assembly 18 during the welding to be effectively released from the gas vent holes.
  • the pre-rolling assembly 18 reinforced by the reinforcing frame 16 is preheated.
  • This preheating is performed using a heating furnace in an ambient atmosphere at a temperature of 300 to 600° C for a holding time of 2 hours or more.
  • a preheating atmosphere is not limited to the ambient atmosphere.
  • the preheating is preferably performed in an inert gas atmosphere, such as an argon gas atmosphere, more preferably a vacuum atmosphere of 5 Pa or less.
  • the preheated assembly is subjected to rolling as one of the plastic workings.
  • conditions of the pre- rolling or preheated assembly 18 for providing a unique advantage of the present invention will be described below.
  • the mixed powder in the pre-heated assembly to be subjected to the rolling process is maintained in powder form without being solidified. That is, the mixed powder is not subjected to a preforming process for allowing a mixed powder to be maintained in a predetermined shape, specifically a process of preforming a mixed powder in an intended shape through press working or pulse-current pressure sintering.
  • the mixed powder is packed in the pre- rolling assembly at a relatively high filling rate, the filling rate is not increased to a level allowing the mixed powder to be changed from the powder state.
  • the mixed powder M maintained in powder form is subjected to the rolling process, it is sandwiched by metal or aluminum members from above and below.
  • a top surface of the mixed powder M is covered by the top wall 14E of the upper casing 14 fully and tightly, and a bottom surface of the mixed powder M is covered by the bottom wall 12E of the lower casing 12 fully and tightly.
  • the pre- rolling assembly 18 having the mixed powder M hermetically sealed in the casing 10 and sandwiched by the aluminum members from above and below is provided as a raw material of a plate- shaped cladded material.
  • the preheated assembly 18 is typically subjected to rolling and formed in an intended shape.
  • a plate-shaped cladded material having a given clad rate of an Al plate and/or an Al casing can be obtained only through cold rolling.
  • hot plastic working a single plastic working may be performed, or plural types of plastic workings may be performed in combination.
  • cold plastic working may be performed.
  • the pre-rolling assembly may be subjected to annealing at a temperature of 300 to 600° C (preferably 400 to 500 ° C) to facilitate the cold plastic working.
  • the pre-rolling assembly 18 is cladded with the aluminum plates, and therefore a surface of the pre-rolling assembly 18 is free from ceramic particles which act as a fracture origin during plastic working and cause accelerated wear of a roll, die or the like. This makes it possible to provide enhanced rollability and obtain an aluminum matrix composite material excellent in strength and surface texture.
  • an obtained hot plastic-worked product has a surface cladded with metal, and the metal clad is tightly bonded with the inner mixed powder M.
  • the hot plastic-worked product is superior in corrosion resistance, impact resistance and thermal conductivity to an aluminum matrix composite material devoid of metal cladding a surface thereof.
  • a surface of the pre-rolling assembly 18 is effectively covered by a protective plate, such as a thin plate made of SUS or Cu.
  • a protective plate such as a thin plate made of SUS or Cu.
  • a rolling temperature in the hot rolling is set at approximately 500 ° C.
  • the preheated assembly 18 may be finished to have a final thickness through this hot rolling.
  • the hot-rolled assembly may be further subjected to warm rolling at a temperature of 200 to 300 'C. Further, the assembly subjected to the first warm rolling may be subjected to second warm rolling at a temperature of 200 ° C or less.
  • the rolled assembly After completion of the rolling process, the rolled assembly is subjected to a heat treatment at a temperature of 300 to 600° C for a predetermined time, i.e., to an annealing process. After completion of the annealing process, the annealed assembly is subjected to a cooling process, and a correcting process for obtaining a desired flatness. Then, opposite lateral edges and front and rear edges of the corrected assembly are cut off to obtain a product having a predetermined shape.
  • a heat treatment at a temperature of 300 to 600° C for a predetermined time, i.e., to an annealing process.
  • the annealed assembly After completion of the annealing process, the annealed assembly is subjected to a cooling process, and a correcting process for obtaining a desired flatness. Then, opposite lateral edges and front and rear edges of the corrected assembly are cut off to obtain a product having a predetermined shape.
  • composition A composition of each material was analyzed by an inductively-coupled plasma (ICP) emission spectrophotometric analysis method.
  • ICP inductively-coupled plasma
  • a specimen cut from each sample was embedded in resin, and subjected to emery grinding and buffing. Then, a metal structure of the specimen was observed by an optical microscope.
  • a B4C ceramic powder was uniformly mixed with an aluminum alloy powder having a composition as shown in Table 1, in an amount of 35 mass%, to prepare a mixed powder M. Then, a lower casing 12 made of an aluminum alloy (JIS A5052P) and formed in an approximately rectangular parallelepiped shape having outside dimensions of 367.7 mm on a side in square-shaped top and bottom surfaces, and 31.6 mm in height, and a wall thickness of 1.6 mm was prepared. Further, an upper casing 14 made of an aluminum alloy (JIS A5052P) and formed in an approximately rectangular parallelepiped shape having outside dimensions of 370.9 mm on a side in square-shaped top and bottom surfaces, and 33.2 mm in height, and a wall thickness of 1.6 mm was prepared. The aluminum alloy (JIS A5052P) had a tensile strength of 195 MPa.
  • first and second reinforcing members 16A, 16B constructing a reinforcing frame 16.
  • first and second reinforcing members 16A, 16B constructing a reinforcing frame 16.
  • second reinforcing members 16A, 16B constructing a reinforcing frame 16.
  • third and fourth reinforcing members 16C, 16D constructing a reinforcing frame 16.
  • the reinforcing frame 16 (i.e., first to fourth reinforcing members 16A to 16D) was made of the same material (JIS A5052P) as that of the lower and upper casing 12, 14.
  • the mixed powder M was supplied into the lower casing 12 while tapping the lower casing 12.
  • an obtained pre-rolling assembly 18 was preheated at 500° C for 2 hours or more, and rolled using a two-high rolling mill (400 KW, ⁇ 870 x 900) at a rolling-initiation temperature of 500° C and a rolling-end temperature of 100° C, to have a final thickness of 1.9 mm.
  • the rolled assembly was subjected to annealing at a temperature of 450 ° C for 4 hours, and then cooled at 200° C.
  • FIGS. 3 to 6 Microscope photographs of the metal structure are shown in FIGS. 3 to 6, wherein: FIG. 3 is a microscope photograph showing a region (100 times magnified) including a portion where a top wall 14E of the upper casing 14 appears as an upper skin layer; FIG. 4 is a microscope photograph partly showing the region (400 times magnified) in FIG. 3; FIG. 5 is a microscope photograph showing a region of an intermediate layer (100 times magnified) made up of the mixed powder M subjected to rolling; and FIG. 6 is a microscope photograph partly showing the region of the intermediate layer (400 times magnified) in FIG. 5.
  • the specimen is rolled to have a sufficiently high density.
  • the upper skin layer formed from the top wall 14E of the upper casing 14 is tightly bonded with the inner mixed powder M.
  • the intermediate layer i.e., a layer made up of the mixed powder M densified or solidified through the rolling
  • the intermediate layer has a high theoretical density ratio of 95% or more which could not be achieved by conventional products (theoretical density ratio: a ratio of a computational density to a measured specific density)
  • the width of the reinforcing frame 16 in addition to the reinforcing frame 16 in the Example 1 having a width of 20.0 mm, five types of reinforcing frames 16 were prepared by changing only the width to 5 mm, 10 mm, 15 mm, 30 mm and 40 mm. Except for this change, the product was made under the same conditions as those in the Example 1. Each of the prepared reinforcing frames 16 was welded to the pre-rolling assembly 18 to prepare five types of samples, and each of the samples was subjected to rolling in the same manner.
  • an additional five types of reinforcing frames 16 were prepared by changing the material of the reinforcing frame 16 in the Example 1 to an aluminum alloy (JIS A6063) and then changing only the width to 5 mm, 10 mm, 15 mm, 30 mm and 40 mm. Except for these changes, the product was made under the same conditions as those in the Example 1.
  • Each of the prepared reinforcing frames 16 was welded to the pre-rolling assembly 18 to prepare five types of samples, and each of the samples was subjected to rolling in the same manner.
  • the aluminum alloy (JIS A6063) had a tensile strength of 95 MPa.
  • each of the reinforcing members 18A to 18D making up the reinforcing frame 18 is required to have a width set to be 4% or more of a length of the upper casing 14 along a direction orthogonal to a rolling direction.
  • a radius of a mill roll of a rolling mill for use in the rolling process is R
  • a thickness of the pre-rolling assembly 18 (before rolling) is HO
  • a thickness of the rolled assembly (after the rolling) is Hl (i.e., (HO - Hl) is a rolled amount per rolling process)
  • the "SQRT (R * (HO - Hl))" in the above inequalities is a value defined as a contact arc length. That is, the left-hand side of each of the inequalities is equivalent to [ (a thickness of the pre-rolling assembly 18) ⁇ (a contact arc length)], and therefore a value of the left-hand side is defined as a shape ratio.
  • Example 1 was verified. The verification result is shown in FIG. 7.
  • the rolling conditions for preventing peeling of the skin layers can be defined using the above inequalities.
  • a matrix material of the mixed powder M comprises a B 4 C ceramic powder and an aluminum powder
  • the matrix material for use in the method of the present invention is not limited to such a composition. It is also understood that a primary component of the matrix material is not limited to aluminum, but may be a powder of any other suitable metal element, such as copper, magnesium, titanium, gallium, iron or indium.
  • the casing used in the method of the present invention is not limited to such a structure, but may have any other suitable structure, for example, the structure of a casing 10' for use in a method according to a second embodiment of the present invention.
  • the method according to the second embodiment will be described below.
  • the second embodiment is different from the first embodiment in only the casing 10', and other components, materials, production process, etc., are almost the same as those in the first embodiment. Thus, the following description will be made about only the casing 10' and the operation of packing and other duplicative descriptions will be omitted.
  • the casing 10' in the second embodiment comprises a casing body 20 formed as a hollow member prepared through an extrusion process to have an inner hollow cavity which is fully opened to the outside in such a manner as to define front and rear open ends located along a rolling direction, a first plug member 22 is adapted to close the front open end, and a second plug member 24 is adapted to close the rear open end.
  • the casing body 20 is made of the same material (JIS A5052P) as that of the casing 10 (upper and lower casings 14, 12) in the first embodiment.
  • the casing body 20 has an integral hollow structure prepared through an extrusion process, as mentioned above. More specifically, the casing body 20 is formed in a flat rectangular parallelepiped shape which integrally has opposed lateral walls 2OA, 2OB each extending along the rolling direction, and a top wall 20C and a bottom wall 2OD. In a rolling process, the casing body 20 is positioned in such a posture (rolling posture) that a longitudinal axis thereof extends along the rolling direction and the top wall 2OC (i.e., top surface) thereof to be rolled extends along a horizontal direction, and is subjected to rolling using a rolling mill in a direction from the front open end toward the rear open end.
  • a posture rolling posture
  • the bottom wall 2OD and the top wall 2OC in the second embodiment correspond, respectively, to the bottom wall 12E of the lower casing 12 and the top wall 14E of the upper casing 14 in the first embodiment.
  • the lateral wall 2OA in the second embodiment corresponds to a combination of the lateral wall 12A of the lower casing 12, the lateral wall 14A of the upper casing 14, and the reinforcing member 16A in the first embodiment.
  • the lateral wall 2OB in the second embodiment corresponds to a combination of the lateral wall 12B of the lower casing 12, the lateral wall 14B of the upper casing 14, and the reinforcing member 16B in the first embodiment.
  • the first plug member 22 is formed in a shape and size fittable into the front open end (specifically, a front opening) of the casing body 20 in a slidable manner to fully close the front open end.
  • the first plug member 22 is fitted into the front open end of the casing body 20 in such a manner that an outer surface of the first plug member 22 becomes flush with a surface of the front open end, and then fixed to the casing body 20 by crimping or welding.
  • the first plug member 22 has a thickness in the rolling direction which is set at a value equal to a total thickness of the front wall 12C of the lower casing 12, the front wall 14C of the upper casing 14, and the reinforcing member 16C of the reinforcing frame 16, in the first embodiment.
  • the second plug member 24 is formed in a shape and size fittable into the rear open end (specifically, a rear opening) of the casing body 20 in a slidable manner to be able to push down a required depth and to fully close the rear open end.
  • the second plug member 24 has a thickness in the rolling direction which is set at a value equal to a total thickness of the rear wall 12D of the lower casing 12, the rear wall 14D of the upper casing 14, and the reinforcing member 16D of the reinforcing frame 16, in the first embodiment.
  • the second plug member 24 is formed with a through-hole
  • the through-hole is serves as a gas vent (i.e., gas release) means to release gas from an inside of the casing body 20 during heating and rolling and is set to be closed by a plug or tape (not shown) during a transportation of the pre-rolling assembly as in the first embodiment.
  • gas vent i.e., gas release
  • Each of the first and second plug members 22, 24 is made of the same material as that of the casing body 20.
  • the casing 10' i.e., an assembly of the casing body 20 and the first and the second plug members 22, 24 fitted in the casing body 20, has outside dimensions equal to those of the pre-rolling assembly 18 (including the reinforcing frame 16) in the first embodiment, and inside dimensions equal to those of an inner hollow cavity defined by the upper and lower casings 14, 12 fitted together.
  • the casing 10' in the second embodiment is integrally formed with the reinforcing frame 16 in the first embodiment.
  • the first plug member 22 is fitted into the first open end of the casing body 20, and fixed by crimping the casing to gas-tightly close the front open end of the casing body 20.
  • the casing body 20 After closing the front open end of the casing body 20, the casing body 20 is positioned in an upstanding posture where the rear open end is located at a top of the casing body 20.
  • the mixed powder M is fed into the casing body 20 from the rear and upper open end thereof at a constant feed rate.
  • the packing process is performed while tapping the casing body 20 or mechanical compaction so as to complete to fill a required quantity of the mixed powder M and increase a density of the mixed powder M to be packed into the casing body 20.
  • the second plug 24 is fitted into the rear open end (that is, the upper open end) of the casing body 20 and put on the upper surface of the mixed power M inr the casing body 20. More specifically, this fitting operation is performed in such a manner that the second plug member 24 (specifically, a bottom surface of the second plug member 24) comes into contact with an upper surface of the mixed powder M packed in the casing body 20, Further, during the fitting operation, the tap operation is continuously performed. Thus, the density of the packed mixed powder M is further increased so that a bulk of the mixed powder M is gradually reduced, and the upper surface of the mixed powder M is gradually lowered. That is, the second plug member 24 will be gradually fitted into the casing body 20 according to the lowering of the upper surface of the mixed powder M.
  • the tap operation and the fitting operation are performed over a time enough to obtain a predetermined density of the mixed powder M.
  • the second plug member 24 is fixed to the casing body 20 by crimping the casing or welding. In this manner, a pre-rolling assembly equivalent to the pre-rolling assembly 18 in the first embodiment is prepared.
  • the pre-rolling assembly i.e., the casing 10' having the mixed powder M packed in the casing body 20
  • the pre-rolling assembly will be subjected to a preheating process and a rolling process to obtain an end product.
  • a verification test using the casing 10' in the second embodiment which has a shape different from that of the casing 10 in the first embodiment was carried out in the same manner as that in the first embodiment (Examples 1 to 3) . As a result, it was verified that the same advantages as those in the first embodiment can be reliably obtained.

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  • Chemical & Material Sciences (AREA)
  • Engineering & Computer Science (AREA)
  • Materials Engineering (AREA)
  • Mechanical Engineering (AREA)
  • Metallurgy (AREA)
  • Organic Chemistry (AREA)
  • Powder Metallurgy (AREA)

Abstract

La présente invention concerne un procédé de production pour matériau composite à matrice d'aluminium comprenant les étapes suivantes : le mélange d'une poudre d'aluminium et d'une poudre céramique pour préparer un mélange de poudre ; la production d'une boîtier inférieur réalisé en aluminium et conformé en une forme de parallélépipède rectangulaire creuse présentant une partie supérieure ouverte, et un élément de fermeture sur le haut du boîtier inférieur réalisé en aluminium et conformé pour la fermeture hermétique de la partie haute ouverte du boîtier inférieur ; le bourrage du mélange de poudre dans le boîtier inférieur ; la fermeture de la partie haute du boîtier inférieur rempli du mélange de poudre, par l'élément de fermeture, pour préparer un ensemble de prélaminage ; et le laminage de l'ensemble préchauffé pour obtenir un matériau composite à matrice d'aluminium, le matériau composite à matrice d'aluminium comportant une paire de plaques métalliques comprenant le mélange de poudre entre elles.
PCT/JP2007/070983 2007-10-23 2007-10-23 Procédé de production pour matériau composite à matrice métallique WO2009054074A1 (fr)

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Cited By (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
JP2010255033A (ja) * 2009-04-23 2010-11-11 Nippon Light Metal Co Ltd 金属基複合材
JP2010255032A (ja) * 2009-04-23 2010-11-11 Nippon Light Metal Co Ltd 金属基複合材
JP2013241675A (ja) * 2013-04-11 2013-12-05 Nippon Light Metal Co Ltd 金属基複合材の製造方法

Citations (4)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
JPS52120207A (en) * 1976-04-02 1977-10-08 Mitsubishi Metal Corp Powder rolling
JPS63125601A (ja) * 1986-11-14 1988-05-28 Mitsubishi Metal Corp 金属粉末から金属板材を製造する方法
WO2004102586A1 (fr) * 2003-05-13 2004-11-25 Nippon Light Metal Company, Ltd. Absorbeur de neutrons a base d'aluminium et son procede de production
JP2007040914A (ja) * 2005-08-05 2007-02-15 Nippon Light Metal Co Ltd 中性子吸収用アルミニウム粉末合金複合材及びその製造方法並びにそれで製造されたバスケット

Patent Citations (4)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
JPS52120207A (en) * 1976-04-02 1977-10-08 Mitsubishi Metal Corp Powder rolling
JPS63125601A (ja) * 1986-11-14 1988-05-28 Mitsubishi Metal Corp 金属粉末から金属板材を製造する方法
WO2004102586A1 (fr) * 2003-05-13 2004-11-25 Nippon Light Metal Company, Ltd. Absorbeur de neutrons a base d'aluminium et son procede de production
JP2007040914A (ja) * 2005-08-05 2007-02-15 Nippon Light Metal Co Ltd 中性子吸収用アルミニウム粉末合金複合材及びその製造方法並びにそれで製造されたバスケット

Cited By (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
JP2010255033A (ja) * 2009-04-23 2010-11-11 Nippon Light Metal Co Ltd 金属基複合材
JP2010255032A (ja) * 2009-04-23 2010-11-11 Nippon Light Metal Co Ltd 金属基複合材
JP2013241675A (ja) * 2013-04-11 2013-12-05 Nippon Light Metal Co Ltd 金属基複合材の製造方法

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