EP0227352A2 - Metal matrix composites - Google Patents
Metal matrix composites Download PDFInfo
- Publication number
- EP0227352A2 EP0227352A2 EP86309433A EP86309433A EP0227352A2 EP 0227352 A2 EP0227352 A2 EP 0227352A2 EP 86309433 A EP86309433 A EP 86309433A EP 86309433 A EP86309433 A EP 86309433A EP 0227352 A2 EP0227352 A2 EP 0227352A2
- Authority
- EP
- European Patent Office
- Prior art keywords
- bismuth
- aluminium
- filler material
- filler
- containing alloy
- 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.)
- Ceased
Links
Classifications
-
- 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
- C22C1/10—Alloys containing non-metals
- C22C1/1036—Alloys containing non-metals starting from a melt
-
- 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
- C22C32/001—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 with only oxides
- C22C32/0015—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 with only oxides with only single oxides as main non-metallic constituents
- C22C32/0036—Matrix based on Al, Mg, Be or alloys thereof
-
- 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
- C22C32/0047—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 with carbides, nitrides, borides or silicides as the main non-metallic constituents
-
- 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
- C22C32/0089—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 with other, not previously mentioned inorganic compounds as the main non-metallic constituent, e.g. sulfides, glass
Definitions
- This invention relates to a method of making metal matrix composites where the metal is aluminium or an alloy thereof.
- Metal matrix composites comprising a refractory inorganic filler material such as silicon carbide or alumina in a matrix of aluminium or an alloy thereof are useful engineering materials, for example where high strength and low density are required as in the motor vehicle and aerospace industries.
- molten Al or Al alloy cannot wet the solid filler material sufficiently for such composites to be made satisfactorily by stirring the filler into the molten metal.
- the invention provides a method of making a solid composite material comprising a refractory, inorganic filler material in a matrix of aluminium or an aluminium-containing alloy such as an aluminium base alloy, which comprises
- the molten Al or alloy takes up at least twice the amount of filler by weight when the bismuth additive is present than when it is absent, and further that the filler is more uniformly dispersed in the matrix when a bismuth additive is used.
- the filler material may be a material known in the art for enhancing the properties of aluminium and aluminium base alloys.
- examples are refractory carbides such as silicon carbide and refractory oxides such as alumina.
- the bismuth additive is a bismuth compound such as bismuth oxide when the dispersion may be prepared in step (i) by intimately mixing fine particle elemental bismuth with particulate filler material, for example of particle size in the range of 5 ⁇ m to 100 ⁇ m wherein the weight of bismuth is preferably less than 10% of the weight of the filler, followed by oxidising the elemental bismuth to bismuth oxide (Bi2O3), e.g. by heating in air at 500°C to 1000°C. Heating in air causes the bismuth to burn and generate smoke thereby facilitating production of a fine oxide dispersion.
- oxidising the elemental bismuth to bismuth oxide e.g. by heating in air at 500°C to 1000°C. Heating in air causes the bismuth to burn and generate smoke thereby facilitating production of a fine oxide dispersion.
- step (i) it may however be possible to prepare the dispersion in step (i) in other ways, for example by mixing the filler material with an aqueous solution of a decomposable bismuth salt such as bismuth nitrate followed by heating to decompose the salt to bismuth oxide.
- a decomposable bismuth salt such as bismuth nitrate
- Step (ii) may be carried out by the known technique of vacuum stirring wherein the dispersion of step (i) is stirred into the molten aluminium or aluminium base alloy in vacuo.
- the aluminium or aluminium base alloy may be at a temperature considerably above its liquidus, for example at 150°C above its liquidus.
- bismuth compounds embrittle aluminium and aluminium base alloys at elevated temperature. It may, therefore, be necessary to add a material capable of reacting with surplus bismuth additive, i.e. a bismuth "getter", between steps (ii) and (iii). Examples of such getters are magnesium and manganese.
- a bismuth getter may not be necessary in all cases; for example, an aluminium base alloy, if used, may contain a getter as a component thereof and hence provide at sufficient quantity of the getter.
- the composite material produced in step (iii) may, for example, be pressure die cast, squeeze cast, chill cast or wrought.
- a shaped composite may be produced directly in step (iii) by cooling the product of step (ii) in a mould.
- the composite produced by this invention may have a range of compositions subject to product and/or processing requirements and restrictions.
- Step (ii) The above dispersion was stirred into an aluminium base alloy (LM6, containing ⁇ 10.5% Si) in vacuo for 2 hours in the temperature range of 740°C to 770°C.
- LM6 aluminium base alloy
- Step (iii) The molten product of step (ii) was cooled to the freezing point of the alloy in about half an hour.
- the alloy had taken up about 20% of its weight of alumina which was fairly uniformly distributed therein on a macro scale.
- the material was capable of being melted and chill cast and pressure die cast without undue difficulty.
- a sample of the material was heated to 850°C and poured through a 10 mm hole under a head of approximately 20 mm to show that it was sufficiently fluid when molten to be cast.
- the material was then heated to 850°C and cast into a cast iron mould. Sections of the resulting casting were examined microscopically where it was observed that the alumina filler material had been retained and that its distribution in the matrix was, if anything, more uniform than in the composite material product of step (iii).
Abstract
Description
- This invention relates to a method of making metal matrix composites where the metal is aluminium or an alloy thereof.
- Metal matrix composites comprising a refractory inorganic filler material such as silicon carbide or alumina in a matrix of aluminium or an alloy thereof are useful engineering materials, for example where high strength and low density are required as in the motor vehicle and aerospace industries. However, molten Al or Al alloy cannot wet the solid filler material sufficiently for such composites to be made satisfactorily by stirring the filler into the molten metal.
- It has now been found that this problem may be ameliorated by using a particular additive with the filler. Thus, the invention provides a method of making a solid composite material comprising a refractory, inorganic filler material in a matrix of aluminium or an aluminium-containing alloy such as an aluminium base alloy, which comprises
- (i) preparing a uniform dispersion of a bismuth additive in the filler material;
- (ii) incorporating the dispersion into the aluminium or aluminium-containing alloy, the aluminium or aluminium-containing alloy being at a temperature above its liquidus; and
- (iii) cooling the product of step (ii) to produce a solid composite material.
- It has been found, in specific examples of this method, that the molten Al or alloy takes up at least twice the amount of filler by weight when the bismuth additive is present than when it is absent, and further that the filler is more uniformly dispersed in the matrix when a bismuth additive is used.
- The filler material may be a material known in the art for enhancing the properties of aluminium and aluminium base alloys. Examples are refractory carbides such as silicon carbide and refractory oxides such as alumina.
- Preferably the bismuth additive is a bismuth compound such as bismuth oxide when the dispersion may be prepared in step (i) by intimately mixing fine particle elemental bismuth with particulate filler material, for example of particle size in the range of 5 µm to 100 µm wherein the weight of bismuth is preferably less than 10% of the weight of the filler, followed by oxidising the elemental bismuth to bismuth oxide (Bi₂O₃), e.g. by heating in air at 500°C to 1000°C. Heating in air causes the bismuth to burn and generate smoke thereby facilitating production of a fine oxide dispersion.
- It may however be possible to prepare the dispersion in step (i) in other ways, for example by mixing the filler material with an aqueous solution of a decomposable bismuth salt such as bismuth nitrate followed by heating to decompose the salt to bismuth oxide.
- Step (ii) may be carried out by the known technique of vacuum stirring wherein the dispersion of step (i) is stirred into the molten aluminium or aluminium base alloy in vacuo. The aluminium or aluminium base alloy may be at a temperature considerably above its liquidus, for example at 150°C above its liquidus.
- The presence of bismuth compounds is known to embrittle aluminium and aluminium base alloys at elevated temperature. It may, therefore, be necessary to add a material capable of reacting with surplus bismuth additive, i.e. a bismuth "getter", between steps (ii) and (iii). Examples of such getters are magnesium and manganese. However, a bismuth getter may not be necessary in all cases; for example, an aluminium base alloy, if used, may contain a getter as a component thereof and hence provide at sufficient quantity of the getter.
- To produce a finished shaped article, the composite material produced in step (iii) may, for example, be pressure die cast, squeeze cast, chill cast or wrought. However, a shaped composite may be produced directly in step (iii) by cooling the product of step (ii) in a mould.
- The composite produced by this invention may have a range of compositions subject to product and/or processing requirements and restrictions.
- The following example illustrates the invention.
- Step (i) Elemental bismuth in the form of fine filings was added to fused and crushed alumina (approximately 9 µm particle size), wherein the weight of bismuth was 2% of that of the alumina, and thoroughly mixed by barrelling. The resulting mixture was then heated in air at 550°C for 2 hours to oxidise the bismuth to bismuth oxide thereby producing a uniform dispersion of bismuth oxide in alumina.
- Step (ii) The above dispersion was stirred into an aluminium base alloy (LM6, containing ≃ 10.5% Si) in vacuo for 2 hours in the temperature range of 740°C to 770°C.
- Step (iii) The molten product of step (ii) was cooled to the freezing point of the alloy in about half an hour.
- In the resulting material, the alloy had taken up about 20% of its weight of alumina which was fairly uniformly distributed therein on a macro scale. The material was capable of being melted and chill cast and pressure die cast without undue difficulty. In particular, a sample of the material was heated to 850°C and poured through a 10 mm hole under a head of approximately 20 mm to show that it was sufficiently fluid when molten to be cast. The material was then heated to 850°C and cast into a cast iron mould. Sections of the resulting casting were examined microscopically where it was observed that the alumina filler material had been retained and that its distribution in the matrix was, if anything, more uniform than in the composite material product of step (iii).
- The above result was considerably superior to any of those obtained in 19 experiments in which the above process steps were repeated but in the absence of a bismuth additive.
Claims (10)
characterised in that the filler material has a bismuth additive uniformly dispersed therein.
Applications Claiming Priority (2)
Application Number | Priority Date | Filing Date | Title |
---|---|---|---|
GB858531070A GB8531070D0 (en) | 1985-12-17 | 1985-12-17 | Metal matrix composites |
GB8531070 | 1985-12-17 |
Publications (2)
Publication Number | Publication Date |
---|---|
EP0227352A2 true EP0227352A2 (en) | 1987-07-01 |
EP0227352A3 EP0227352A3 (en) | 1989-03-08 |
Family
ID=10589894
Family Applications (1)
Application Number | Title | Priority Date | Filing Date |
---|---|---|---|
EP86309433A Ceased EP0227352A3 (en) | 1985-12-17 | 1986-12-03 | Metal matrix composites |
Country Status (3)
Country | Link |
---|---|
EP (1) | EP0227352A3 (en) |
JP (1) | JPS62146229A (en) |
GB (2) | GB8531070D0 (en) |
Families Citing this family (2)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
JPH072980B2 (en) * | 1990-09-20 | 1995-01-18 | 大同メタル工業株式会社 | Composite sliding material |
GB9302921D0 (en) * | 1993-02-13 | 1993-03-31 | Atomic Energy Authority Uk | Particulate metal matrix composites |
Citations (4)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
DE1111836B (en) * | 1957-07-05 | 1961-07-27 | Gen Electric Co Ltd | Process for the preparation of a suspension of thorium oxide in the melt of a low-melting metal or such an alloy and application to nuclear reactors |
FR1276929A (en) * | 1960-12-28 | 1961-11-24 | Bendix Corp | Improvements to friction materials |
GB959442A (en) * | 1960-06-13 | 1964-06-03 | Du Pont | Improvements in or relating to metalliferous compositions |
US4189522A (en) * | 1975-08-08 | 1980-02-19 | Daido Metal Company, Ltd. | Multi-layer sliding material and method for manufacturing the same |
-
1985
- 1985-12-17 GB GB858531070A patent/GB8531070D0/en active Pending
-
1986
- 1986-12-03 GB GB8628885A patent/GB2184133B/en not_active Expired
- 1986-12-03 EP EP86309433A patent/EP0227352A3/en not_active Ceased
- 1986-12-10 JP JP29460186A patent/JPS62146229A/en active Pending
Patent Citations (4)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
DE1111836B (en) * | 1957-07-05 | 1961-07-27 | Gen Electric Co Ltd | Process for the preparation of a suspension of thorium oxide in the melt of a low-melting metal or such an alloy and application to nuclear reactors |
GB959442A (en) * | 1960-06-13 | 1964-06-03 | Du Pont | Improvements in or relating to metalliferous compositions |
FR1276929A (en) * | 1960-12-28 | 1961-11-24 | Bendix Corp | Improvements to friction materials |
US4189522A (en) * | 1975-08-08 | 1980-02-19 | Daido Metal Company, Ltd. | Multi-layer sliding material and method for manufacturing the same |
Non-Patent Citations (1)
Title |
---|
PATENT ABSTRACTS OF JAPAN, vol. 10, no. 123 (C-344)[2180], 8th May 1986; & JP-A-60 251 150 (OKUNO SEIYAKU KOGYO K.K.) 11-12-1985 * |
Also Published As
Publication number | Publication date |
---|---|
GB2184133A (en) | 1987-06-17 |
JPS62146229A (en) | 1987-06-30 |
GB8531070D0 (en) | 1986-01-29 |
EP0227352A3 (en) | 1989-03-08 |
GB2184133B (en) | 1989-07-12 |
GB8628885D0 (en) | 1987-01-07 |
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Effective date: 19910301 |
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Free format text: STATUS: THE APPLICATION HAS BEEN REFUSED |
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18R | Application refused |
Effective date: 19920515 |
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RIN1 | Information on inventor provided before grant (corrected) |
Inventor name: BROOMFIELD, GEOFFREY HUGH |