METAL MATRIX COMPOSITE AND METHOD OF FORMING

• US 20150376745A1
• Filed: 02/11/2014
• Published: 12/31/2015
• Est. Priority Date: 02/11/2013
• Status: Active Grant

• Current Assignee: National Research Council Canada
• Original Assignee: National Research Council Canada
• Inventors: BOUCHARD, Dominique
• Granted Patent: US 9,945,012 B2
• Time in Patent Office: Days
• US Class Current: 1/1
• CPC Class Codes: B22D 19/14 the objects being filamentary or particulate in form making alloys containing fibres or filaments by contacting the fibres or filaments with molten metal C22C47/08
• CPC Class Codes: C22B 21/0084 melting and handling molten aluminium C22B21/02, C22B21/04 and C22B21/06 take precedence
• CPC Class Codes: C22B 21/06 refining electrolytic refining C25C; C22B21/0046, C22B21/0061 take precedence
• CPC Class Codes: C22B 21/062 using salt or fluxing agents C22B21/064, C22B21/066, and C22B21/068 take precedence
• CPC Class Codes: C22C 1/02 by melting C22C1/1036 takes precedence
• CPC Class Codes: C22C 1/026 Alloys based on aluminium
• CPC Class Codes: C22C 1/1036 starting from a melt
• CPC Class Codes: C22C 1/1047 by mixing and casting liquid metal matrix composites
• CPC Class Codes: C22C 14/00 Alloys based on titanium
• CPC Class Codes: C22C 21/00 Alloys based on aluminium
• CPC Class Codes: C22C 29/12 based on oxides
• CPC Class Codes: C22C 30/00 Alloys containing less than 50% by weight of each constituent
• CPC Class Codes: C22C 32/0031 Matrix based on refractory metals, W, Mo, Nb, Hf, Ta, Zr, Ti, V or alloys thereof
• CPC Class Codes: C22C 32/0036 Matrix based on Al, Mg, Be or alloys thereof
• CPC Class Codes: C22C 5/04 Alloys based on a platinum group metal

Abstract

Use of Ca in metal matrix composites (MMC) allows for incorporation of small and large amounts of ceramic (e.g. rutile Ti0₂) into the metal (Al, or its alloys). Calcium remains principally out of the matrix and is part of a boundary layer system that has advantages for integrity of the MMC. Between 0.005 and 10 wt. % calcium (Ca) may be included, and more than 50 wt. % of rutile has been shown to be integrated. Rutile may therefore be used to reduce melt loss due to calcium from an aluminum or aluminum alloy melt.

Claims

1. A method for producing a metal matrix composite comprising:

stirring a reinforcement with an aluminum-containing molten or semisolid metal or alloy and between 0.005 and 10 wt. % calcium (Ca), wherein the reinforcement is composed of particles each having a surface with a surface area bearing at least 20% of titanium oxide (TiO₂), and the TiO₂ is of crystal form other than anatase; and

cooling the mixture to produce a solid metal matrix composite.

2. The method of claim 1 wherein the reinforcement is a cermet or ceramic powder including the TiO₂, or a compound coated with the TiO₂.

3. The method of claim 1 wherein the TiO₂ is in a rutile crystal form.

4. The method of claim 1 wherein the mixture consists of at least 60 wt. %, more preferably 80 wt. %, more preferably 90 wt. %, more preferably 95 wt. %, more preferably 97 wt. % of the reinforcement and molten metal.

5. The method of claim 1 wherein the molten or semisolid metal is liquid aluminum with at least 80 wt. % or more of Al.

6. The method of claim 1 wherein the molten metal includes aluminum, and at least one alloying metal in liquid or semisolid form with the aluminum, other than magnesium.

7. The method of claim 1 wherein the particles are spherical, cubic, prismatic, polyhedral, angular, amorphous, elongated, rod-like, tubular, conic, fibrous, filamentary, platelet-like, disc-like, irregular, or any combination of the above.

8. The method of claim 1 wherein the surfaces of the particles are flat, or curved, smooth or rough, randomly textured or patterned, concave or convex, or any combination of the above.

9. The method of claim 1 wherein the particles have a predefined distribution of dimensions, with less than 10% of the powders having dimensions greater than a maximum dimension, which is less than 1 cm, and with less than 10% of the powders having dimensions smaller than a minimum dimension, which is greater than 10 nm.

10. The method of claim 1 wherein each surface of the typical particle has a surface area with at least 20% of TiO₂.

11. The method of claim 10 wherein each surface of the typical particle bears at least 60% of TiO₂.

12. The method of claim 1 wherein cooling the mixture to produce a solid metal matrix composite comprises:

sandcasting, die casting, centrifugal casting, compocasting, thixocasting, rheocasting, thixomolding or other semisolid casting, pressure die casting, injection molding or extrusion.

13. A product of the method of claim 3.

14. A metal matrix composite (MMC) comprising:

a metal matrix of aluminum or an alloy of aluminum; and

numerous sub-milimeter dimension embedded particles of a ceramic distributed throughout the metal matrix, the embedded particles comprising titanium oxide (TiO₂) in crystal form other than anatase,

wherein 0.005 to 10 wt. % calcium is present, and a concentration of calcium within the embedded particles and surrounding the embedded particles is more than double a concentration of the calcium in the metal matrix away from the embedded particles.

15. The MMC of claim 0 wherein the calcium is more highly concentrated at a periphery of the particles than within the embedded particles.

16. The MMC of claim 0 wherein the ceramic particles include crystals of rutile titanium oxide (TiO₂), and these particles are surrounded by calcium oxide and aluminum oxide.

17. The MMC of claim 0 wherein the ceramic particles are coated with a ceramic oxide, boride, carbide, nitride or graphite.

18. The MMC of claim 0 wherein the ceramic particles are coated with an oxide or boride, or a ceramic that has a naturally formed oxidization layer.

19. A method for reducing melt loss due to calcium defects in parts formed from an aluminum or aluminum alloy melt, the method comprising estimating a molar amount of calcium present in the melt, and adding at least an equal molar amount of rutile titania to the aluminum or aluminum alloy melt.