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US4985202A Expired / Lapsed US ⏱️ 0.0 years remaining

Process for forming porous metal-second phase composites

Assignee: Lockheed Martin Corp
•
Filing: 1989-08-28
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Granted: 1991-01-15
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Expires: 2009-08-28
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Abstract

Abstract A method is taught for the in-situ precipitation of second phase materials, such as ceramic or intermetallic particles, in a substantial volume fraction of solvent metal matrix. The invention involves the propagating reaction of the second phase-forming constituents in a solvent metal medium to provide a porous composite of finely-dispersed second phase particles in the metal matrix. Exemplary materials include titanium carbide or titanium diboride in an aluminum matrix.

Inventors

  • 👤 William C. Moshier
  • 👤 John M. Brupbacher
  • 👤 Leontios Christodoulou
  • 👤 Dennis C. Nagle

Bibliographic Details

Application Number —
Jurisdiction US
Data Source google_patents
Last Synchronized 2026-10-26 01:27
CPC Classifications
C; C22; C22C; C22C49/00; C22C49/14; B; B22; B22F; B22F3/00; B22F3/10; B22F3/11; B22F3/1143; B22F3/23; B22F9/00; B22F9/02; B22F9/14; B82; B82Y; B82Y30/00; C22C29/00; C22C29/14; C22C32/00; C22C32/0047; C22C32/0073

Claims Analysis

Total Claims: 77
Claim 1
Independent Claim 139 words
A method for the production of porous metal-second phase composite material, the method comprising precipitating at least one second phase material in a solvent metal by locally igniting a mixture comprising reactive second phase forming constituents and at least about 20 volume percent of a substantially nonreactive solvent metal in which the second phase-forming constituents are move soluble than the second phase material, substantially at or below atmospheric pressure and at a temperature at which sufficient diffusion of the reactive second phase forming constituents into the substantially nonreactive solvent metal occurs to cause a substantially isothermal second phase forming reaction of the constituents to thereby precipitant second phase particles in the solvent metal so as to produce a solid composite material having a porosity of at least 10 percent comprising finely divided second phase particles in the metal matrix.
Claim 2
Independent Claim 139 words
A method for the production of porous metal-second phase composite material, the method comprising precipitating at least one second phase material in a solvent metal by locally igniting a mixture comprising reactive second phase forming constituents and at least about 20 volume percent of a substantially nonreactive solvent metal in which the second phase-forming constituents are move soluble than the second phase material, substantially at or below atmospheric pressure and at a temperature at which sufficient diffusion of the reactive second phase forming constituents into the substantially nonreactive solvent metal occurs to cause a substantially isothermal second phase forming reaction of the constituents to thereby precipitant second phase particles in the solvent metal so as to produce a solid composite material having a porosity of at least 10 percent comprising finely divided second phase particles in the metal matrix.
Claim 3
Dependent Claim 20 words
The method as set forth in claim 1, wherein the temperature is about the melting temperature of the solvent metal.
Claim 4
Dependent Claim 26 words
The method as set forth in claim 1, wherein the reactive second phase-forming constituents and the substantially nonreactive solvent metal are each provided as individual elements.
Claim 5
Dependent Claim 19 words
The method as set forth in claim 1, wherein the second phase-forming reaction is initiated in the solid state.
Claim 6
Dependent Claim 18 words
The method as set forth in claim 1, wherein the second phase-forming reaction occurs in the liquid state.
Claim 7
Dependent Claim 23 words
The method as set forth in claim 1, wherein the second phase-forming constituents are each provided as an alloy of the solvent metal.
Claim 8
Dependent Claim 19 words
The method as set forth in claim 6, wherein the second phase-forming reaction takes place in the liquid state.
Claim 9
Dependent Claim 20 words
The method as set forth in claim 1 wherein the mixture is compressed to a compact prior to local ignition.
Claim 10
Dependent Claim 35 words
The method as set forth in claim 1, wherein at least one second phase-forming constituent is provided as an alloy of the solvent metal, and the other second phase-forming constituents are provided as individual elements.
Claim 11
Dependent Claim 27 words
The method as set forth in claim 1, wherein the particulate second phase is titanium diboride, zirconium diboride, zirconium disilicide, zirconium carbide, titanium carbide, or titanium nitride.
Claim 12
Dependent Claim 20 words
The method as set forth in claim 1, wherein the second phase in substantially less than 5 microns in size.
Claim 13
Dependent Claim 18 words
The method as set forth in claim 1, wherein the second phase-forming constituents are contacted in stoichiometric proportions.
Claim 14
Dependent Claim 18 words
The method as set forth in claim 1, wherein one second phase-forming constituent is present in stoichiometric excess.
Claim 15
Dependent Claim 15 words
The method as set forth in claim 1, wherein the second phase is a ceramic.
Claim 16
Dependent Claim 15 words
The method as set forth in claim 1, wherein the second phase is an intermetallic.
Claim 17
Dependent Claim 16 words
The method as set forth in claim 1, wherein the second phase is submicron in size.
Claim 18
Dependent Claim 22 words
The method as set forth in claim 1, wherein the concentration of solvent metal matrix is greater than 30 percent by volume.
Claim 19
Dependent Claim 24 words
The method as set forth in claim 1, further comprising recovering a porous metal-second phase composite material having a substantially uniform distribution of particles.
Claim 20
Dependent Claim 23 words
The method as set forth in claim 1, wherein the particle size of second phase particles is between about 0.1 and 3 microns.
Claim 21
Dependent Claim 22 words
The method as set forth in claim 1, wherein the metal-second phase composite material has a porosity of greater than 25 percent.
Claim 22
Dependent Claim 22 words
The method as set forth in claim 1, wherein the reactive second-phase forming constituents are shaped in the form of a rod.
Claim 23
Dependent Claim 22 words
The method as set forth in claim 1, wherein the reactive second-phase forming constituents are compressed in the shape of a rod.
Claim 24
Independent Claim 19 words
The method as set forth in claim, wherein the second phase particles are substantially encapsulated by solvent matrix metal.
Claim 25
Dependent Claim 17 words
The method as set forth in claim 1, wherein the reaction further comprises an isothermal wave front.
Claim 26
Independent Claim 131 words
A method for dispersion of a second phase in a metal, metal alloy, or intermetallic matrix, the method comprising steps of: (a) preparing a mixture of reactive second phase-forming constituents and at least about 20 volume percent of a nonreactive solvent metal in which the second phase-forming constituents are moe soluble that the second phase; (b) locally heating the mixture substantially at or below atmospheric pressure to a reaction initiation temperature approximating the melting point of the solvent metal to initiate a substantially isothermal reaction; (c) permitting the reaction wave front to propagate and to further heat the mixture, consuming the second phase-forming constituents, forming a distribution of second phase particles in the matrix; and (d) recovering a solid metal-second phase composite material having a porosity of at least 10 percent.
Claim 27
Independent Claim 131 words
A method for dispersion of a second phase in a metal, metal alloy, or intermetallic matrix, the method comprising steps of: (a) preparing a mixture of reactive second phase-forming constituents and at least about 20 volume percent of a nonreactive solvent metal in which the second phase-forming constituents are moe soluble that the second phase; (b) locally heating the mixture substantially at or below atmospheric pressure to a reaction initiation temperature approximating the melting point of the solvent metal to initiate a substantially isothermal reaction; (c) permitting the reaction wave front to propagate and to further heat the mixture, consuming the second phase-forming constituents, forming a distribution of second phase particles in the matrix; and (d) recovering a solid metal-second phase composite material having a porosity of at least 10 percent.
Claim 28
Dependent Claim 29 words
The method as set forth in claim 25, wherein at least one second phase-forming constituent is a transition metal of the third to sixth groups of the Periodic Table.
Claim 29
Dependent Claim 54 words
The method as set forth in claim 25, wherein at least one second phase-forming constituent is aluminum, titanium, silicon, boron, carbon, sulfur, tantalum, thorium, yttrium, cobalt, nickel, molybdenum, tungsten, vanadium, zirconium, niobium, hafnium, magnesium, scandium, lanthanum, chromium, oxygen, nitrogen, lithium, beryllium, iron, manganese, zinc, tin, copper, silver, gold, platinum or a rare earth element.
Claim 30
Dependent Claim 45 words
The method as set forth in claim 27 wherein the solvent metal is aluminum, nickel, titanium, copper, vanadium, chromium, manganese, cobalt, iron, silicon, molybdenum, beryllium, silver, gold, platinum, niobium, tantalum, hafnium, zirconium, magnesium, lead, zinc, tin, tungsten, antimony, bismuth, or an alloy of such metals.
Claim 31
Dependent Claim 22 words
The method as set forth in claim 25, wherein the second phase-forming constituents and the solvent metal are provided as individual elements.
Claim 32
Dependent Claim 17 words
The method as set forth in claim 29, wherein the reaction takes place in the liquid state.
Claim 33
Dependent Claim 29 words
The method as set forth in claim 30, wherein the solvent metal is aluminum, zinc, magnesium, copper, lead, nickel, chromium, iron, titanium, cobalt, or an alloy of such metals.
Claim 34
Dependent Claim 27 words
The method as set forth in claim 31, wherein at least one second phase-forming constituent is aluminum, silicon, titanium, hafnium, tantalum, zirconium, magnesium, vanadium, nickel, or tungsten.
Claim 35
Dependent Claim 23 words
The method as set forth in claim 32, wherein at least one other second phase-forming constituent is aluminum, boron, silicon, nitrogen, or carbon.
Claim 36
Dependent Claim 18 words
The method as set forth in claim 33, wherein the solvent metal is aluminum or an alloy thereof.
Claim 37
Dependent Claim 18 words
The method as set forth in claim 34, wherein the second phase is titanium diboride or titanium carbide.
Claim 38
Dependent Claim 23 words
The method as set forth in claim 25, wherein the second phase-forming constituents are each provided as an alloy of the solvent metal.
Claim 39
Dependent Claim 29 words
The method as set forth in claim 36, wherein the solvent metal is aluminum, zinc, magnesium, copper, lead, nickel, chromium, iron, titanium, cobalt, or an alloy of such metals.
Claim 40
Dependent Claim 31 words
The method as set forth in claim 37, wherein the second phase-forming constituents are selected from aluminum, hafnium, tantalum , vanadium, nickel, tungsten, titanium, zirconium, magnesium, boron, silicon, nitrogen, and carbon.
Claim 41
Dependent Claim 18 words
The method as set forth in claim 36 wherein the solvent metal is aluminum or an alloy thereof.
Claim 42
Dependent Claim 24 words
The method as set forth in claim 39, wherein the second phase-forming constituents are selected from aluminum, titanium, zirconium, magnesium, boron, silicon, or carbon.
Claim 43
Dependent Claim 29 words
The method as set forth in claim 36, wherein the second phase material is titanium diboride or titanium carbide and the solvent metal is aluminum or an alloy thereof.
Claim 44
Dependent Claim 38 words
The method as set forth in claim 25, wherein at least one second phase-forming constituent is provided as an individual element, and at least one other second phase-forming constituent is provided as an alloy of the solvent metal.
Claim 45
Dependent Claim 28 words
The method as set forth in claim 42, wherein the solvent metal is aluminum, zinc, magnesium, copper, nickel, chromium, iron, titanium, cobalt, or an alloy of such metals.
Claim 46
Dependent Claim 24 words
The method as set forth in claim 43, wherein the second phase-forming constituents are selected from aluminum, titanium, zirconium, magnesium, boron, silicon, and carbon.
Claim 47
Dependent Claim 23 words
The method as set forth in claim 44, wherein the solvent metal is aluminum and the second phase-forming constituents are titanium and boron.
Claim 48
Dependent Claim 27 words
The method as set forth in claim 25, wherein the particulate second phase is titanium diboride, zirconium diboride, titanium carbide, zirconium disilicide, zirconium carbide, or titanium nitride.
Claim 49
Dependent Claim 20 words
The method as set forth in claim 46, wherein the second phase is substantially less than 5 microns in size.
Claim 50
Dependent Claim 18 words
The method as set forth in claim 25, wherein the second phase-forming constituents are contacted in stoichiometric proportions.
Claim 51
Dependent Claim 18 words
The method as set forth in claim 25, wherein one second phase-forming constituent is provided in stoichiometric excess.
Claim 52
Dependent Claim 14 words
The method as set forth claim 25, wherein the second phase is a ceramic.
Claim 53
Dependent Claim 14 words
The method as set forth claim 25, wherein the second phase is an intermetallic.
Claim 54
Dependent Claim 21 words
The method as set forth in claim 25, wherein the concentration of solvent metal is greater than 30 percent by volume.
Claim 55
Dependent Claim 21 words
The method as set forth in claim 25, wherein the metal-second phase composite material comprises a substantially uniform distribution of particles.
Claim 56
Dependent Claim 23 words
The method as set forth in claim 25, wherein the particle size of second phase particles is between about 0.1 and 3 microns.
Claim 57
Dependent Claim 22 words
The method as set forth in claim 25, wherein the metal-second phase composite material has a porosity of greater than 25 percent.
Claim 58
Dependent Claim 19 words
The method as set forth in claim 25, wherein the mixture is shaped in the form of a rod.
Claim 59
Dependent Claim 19 words
The method as set forth in claim 25, wherein the mixture is compressed in the shape of a rod.
Claim 60
Dependent Claim 19 words
The method as set forth in claim 25, wherein the second phase particles are substantially encapsulated by solvent metal.
Claim 61
Dependent Claim 17 words
The method as set forth in claim 25, wherein reaction propagation further comprises an isothermal wave front.
Claim 62
Independent Claim 135 words
A method for the production of porous metal-second phase composite materials, the method comprising precipitating at least one second phase material in solvent matrix by locally igniting a mixture of reactive second phase-forming constituents and at lest about 20 volume percent of a substantially nonreactive solvent metal in which the second phase-forming constituents are more soluble than the second phase, substantially at or below atmospheric pressure and at a temperature at which sufficient diffusion of the constituents into the solvent metal occurs, to cause propagation of a substantially isothermal reaction of the reactive second phase-forming constituents to increase the temperature to a temperature exceeding the melting temperature of the solvent metal, to precipitate the second phase in the solvent metal, thereby forming a metal-second phase composite material having a porosity of at least 10 percent.
Claim 63
Independent Claim 135 words
A method for the production of porous metal-second phase composite materials, the method comprising precipitating at least one second phase material in solvent matrix by locally igniting a mixture of reactive second phase-forming constituents and at lest about 20 volume percent of a substantially nonreactive solvent metal in which the second phase-forming constituents are more soluble than the second phase, substantially at or below atmospheric pressure and at a temperature at which sufficient diffusion of the constituents into the solvent metal occurs, to cause propagation of a substantially isothermal reaction of the reactive second phase-forming constituents to increase the temperature to a temperature exceeding the melting temperature of the solvent metal, to precipitate the second phase in the solvent metal, thereby forming a metal-second phase composite material having a porosity of at least 10 percent.
Claim 64
Independent Claim 122 words
A method for providing a second phase in a metallic matrix, the method comprising steps of: (a) preparing a mixture of reactive second phase-forming constituents and at least about 20 volume percent of nonreactive solvent metal in which the second phase-forming constituents are more soluble than the second phase; (b) locally heating the mixture substantially at or below atmospheric pressure to a reaction initiation temperature approximating the melting point of the solvent metal to initiate a substantially isothermal reaction wave front; (c) permitting the exothermic reaction to further heat the mixture and to propagate, forming a uniform distribution of second phase particles in a metallic matrix; and (d) recovering a metal-second phase composite material having a porosity of at least 10 percent.
Claim 65
Independent Claim 122 words
A method for providing a second phase in a metallic matrix, the method comprising steps of: (a) preparing a mixture of reactive second phase-forming constituents and at least about 20 volume percent of nonreactive solvent metal in which the second phase-forming constituents are more soluble than the second phase; (b) locally heating the mixture substantially at or below atmospheric pressure to a reaction initiation temperature approximating the melting point of the solvent metal to initiate a substantially isothermal reaction wave front; (c) permitting the exothermic reaction to further heat the mixture and to propagate, forming a uniform distribution of second phase particles in a metallic matrix; and (d) recovering a metal-second phase composite material having a porosity of at least 10 percent.
Claim 66
Independent Claim 165 words
A method for dispersion of second phase dispersoids in a metallic matrix, the method comprising forming a reaction mixture of reactive second phase-forming constituents in the presence of a substantial volume fraction of at least two metals, at least one of which acts as a solvent metal in which the second phase-forming constituents are more soluble than the second phase dispersoids, holding the mixture substantially at or below atmospheric pressure, raising the temperature of the reaction mixture locally to a temperature at which sufficient diffusion of the second phase-forming constituents into the lowest melting solvent metal occurs to initiate a substantially isothermal reaction of the constituents, whereby the exothermic heat of reaction of the constituents causes the temperature of the reaction mixture to locally exceed the melting point of the highest melting metal, permitting propagation of the reaction, and dispersion of the second phase dispersoid in an alloy to thereby form a solid metal-second phase composite material having a porosity of at least 10 percent.
Claim 67
Independent Claim 165 words
A method for dispersion of second phase dispersoids in a metallic matrix, the method comprising forming a reaction mixture of reactive second phase-forming constituents in the presence of a substantial volume fraction of at least two metals, at least one of which acts as a solvent metal in which the second phase-forming constituents are more soluble than the second phase dispersoids, holding the mixture substantially at or below atmospheric pressure, raising the temperature of the reaction mixture locally to a temperature at which sufficient diffusion of the second phase-forming constituents into the lowest melting solvent metal occurs to initiate a substantially isothermal reaction of the constituents, whereby the exothermic heat of reaction of the constituents causes the temperature of the reaction mixture to locally exceed the melting point of the highest melting metal, permitting propagation of the reaction, and dispersion of the second phase dispersoid in an alloy to thereby form a solid metal-second phase composite material having a porosity of at least 10 percent.
Claim 68
Independent Claim 173 words
A method for dispersion of second phase dispersoids in a metal matrix, the method comprising forming a reaction mixture of reaction second phase-forming constituents in the presence of at least about 20 volume percent of a mixture of at least two metals, at least one of which acts as a solvent metal in which the second phase-forming constituents are more soluble than the second phase dispersoids, holding the mixture substantially at or below atmospheric pressure, raising the temperature of the reaction mixture locally to a temperature at which sufficient diffusion of the second phase-forming constituents into the lowest melting solvent metal occurs to initiate a substantially isothermal reaction of the constituents, whereby the exothermic heat of reaction of the constituents causes the temperature of the reaction mixture to exceed the melting point of the lowest melting point solvent metal, permitting propagation of the reaction and dispersion of the second phase dispersoids in a mixed metal matrix to thereby form a solid metal-second phase composite material having a porosity of at least 10 percent.
Claim 69
Independent Claim 173 words
A method for dispersion of second phase dispersoids in a metal matrix, the method comprising forming a reaction mixture of reaction second phase-forming constituents in the presence of at least about 20 volume percent of a mixture of at least two metals, at least one of which acts as a solvent metal in which the second phase-forming constituents are more soluble than the second phase dispersoids, holding the mixture substantially at or below atmospheric pressure, raising the temperature of the reaction mixture locally to a temperature at which sufficient diffusion of the second phase-forming constituents into the lowest melting solvent metal occurs to initiate a substantially isothermal reaction of the constituents, whereby the exothermic heat of reaction of the constituents causes the temperature of the reaction mixture to exceed the melting point of the lowest melting point solvent metal, permitting propagation of the reaction and dispersion of the second phase dispersoids in a mixed metal matrix to thereby form a solid metal-second phase composite material having a porosity of at least 10 percent.
Claim 70
Independent Claim 131 words
A method for dispersion of at least one intermetallic material in a metallic matrix, comprising steps of: (a) preparing a mixture of reactive intermetallic-forming constituents and a substantial volume fraction of nonreactive solvent metal, metal alloy, or intermetallic in which the intermetallic-forming constituents are more soluble than the intermetallic material; (b) locally heating the mixture substantially at or below atmospheric pressure to a reaction initiation temperature approximating the melting point of the solvent metal, metal alloy or intermetallic; (c) permitting the resultant exothermic reaction to raise the temperature of the mixture to a temperature exceeding the melting point of the solvent metal, and to propagate, as a substantially isothermal wave front consuming the intermetallic-forming constituents; and (d) recovering a solid metal-intermetallic composite material having a porosity of at least 10 percent.
Claim 71
Independent Claim 131 words
A method for dispersion of at least one intermetallic material in a metallic matrix, comprising steps of: (a) preparing a mixture of reactive intermetallic-forming constituents and a substantial volume fraction of nonreactive solvent metal, metal alloy, or intermetallic in which the intermetallic-forming constituents are more soluble than the intermetallic material; (b) locally heating the mixture substantially at or below atmospheric pressure to a reaction initiation temperature approximating the melting point of the solvent metal, metal alloy or intermetallic; (c) permitting the resultant exothermic reaction to raise the temperature of the mixture to a temperature exceeding the melting point of the solvent metal, and to propagate, as a substantially isothermal wave front consuming the intermetallic-forming constituents; and (d) recovering a solid metal-intermetallic composite material having a porosity of at least 10 percent.
Claim 72
Independent Claim 125 words
A method for dispersion of at least one ceramic material in a metallic matrix, comprising steps of: (a) preparing a mixture of reactive ceramic-forming constituents and t least about 20 volume percent of nonreactive solvent metal in which the ceramic-forming constituents are more soluble than the ceramic material; (b) locally heating the mixture substantially at or below atmospheric pressure to a reaction initiation temperature approximating the melting point of the solvent metal; (c) permitting the resultant exothermic reaction to raise the temperature of the mixture to a temperature exceeding the melting point of the solvent metal, and to propagate, as a substantially isothermal wave front consuming the ceramic-forming constituents; and (d) recovering a slid metal-ceramic composite material having a porosity of at least 10 percent.
Claim 73
Independent Claim 125 words
A method for dispersion of at least one ceramic material in a metallic matrix, comprising steps of: (a) preparing a mixture of reactive ceramic-forming constituents and t least about 20 volume percent of nonreactive solvent metal in which the ceramic-forming constituents are more soluble than the ceramic material; (b) locally heating the mixture substantially at or below atmospheric pressure to a reaction initiation temperature approximating the melting point of the solvent metal; (c) permitting the resultant exothermic reaction to raise the temperature of the mixture to a temperature exceeding the melting point of the solvent metal, and to propagate, as a substantially isothermal wave front consuming the ceramic-forming constituents; and (d) recovering a slid metal-ceramic composite material having a porosity of at least 10 percent.
Claim 74
Independent Claim 142 words
A method for dispersing dispersoid particles of an intermetallic material and a ceramic material in a metal matrix, the method comprising steps of: (a) preparing a mixture of reactive intermetallic and ceramic-forming constituents and at least about 20 volume percent of nonreactive solvent metal in which the intermetallic-forming constituents and the ceramic-forming constituents are more soluble than the intermetallic or the ceramic material, respectively; (b) locally heating the mixture substantially at or below atmospheric pressure to a reaction initiation temperature approximating the melting point of the solvent metal; (c) initiating an exothermic reaction to raise the temperature of the mixture to a temperature exceeding the melting point of the solvent metal, and to propagate, as a substantially isothermal wave front consuming the intermetallic-forming constituents and ceramic-forming constituents; and (d) recovering a solid composite material having a porosity of at least 10 percent.
Claim 75
Independent Claim 142 words
A method for dispersing dispersoid particles of an intermetallic material and a ceramic material in a metal matrix, the method comprising steps of: (a) preparing a mixture of reactive intermetallic and ceramic-forming constituents and at least about 20 volume percent of nonreactive solvent metal in which the intermetallic-forming constituents and the ceramic-forming constituents are more soluble than the intermetallic or the ceramic material, respectively; (b) locally heating the mixture substantially at or below atmospheric pressure to a reaction initiation temperature approximating the melting point of the solvent metal; (c) initiating an exothermic reaction to raise the temperature of the mixture to a temperature exceeding the melting point of the solvent metal, and to propagate, as a substantially isothermal wave front consuming the intermetallic-forming constituents and ceramic-forming constituents; and (d) recovering a solid composite material having a porosity of at least 10 percent.
Claim 76
Independent Claim 101 words
A method for the production of porous metal-second phase composite material, the method comprising forming at least one second phase material in nonreactive metal by locally igniting a mixture comprising reactive second phase-forming constituents in the presence of at least about 20 volume percent of a substantially nonreactive metal substantially at or below atmospheric pressure and at a temperature that causes a substantially isothermal propagating second phase-forming reaction of the constituents to propagate as an isothermal wave front, to thereby form second phase particles in the metal and recovering a solid composite material having a porosity of at least 10 percent.
Claim 77
Independent Claim 101 words
A method for the production of porous metal-second phase composite material, the method comprising forming at least one second phase material in nonreactive metal by locally igniting a mixture comprising reactive second phase-forming constituents in the presence of at least about 20 volume percent of a substantially nonreactive metal substantially at or below atmospheric pressure and at a temperature that causes a substantially isothermal propagating second phase-forming reaction of the constituents to propagate as an isothermal wave front, to thereby form second phase particles in the metal and recovering a solid composite material having a porosity of at least 10 percent.

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