Metal matrix composites

Abstract

A method of forming a metal matrix composite component comprises: providing a body defining a mould cavity; covering a first surface of the mould cavity with a first reinforcement material; restraining the first reinforcement material relative to the body to restrict movement of the first reinforcement material in the mould cavity; adding a second reinforcement material to the mould cavity, the second reinforcement material being in contact with the first reinforcement material; adding molten metal to the mould cavity such that the first reinforcement material and the second reinforcement material become embedded in a continuous metal matrix when the molten metal solidifies.

1 . A method of forming a metal matrix composite component, comprising:
 providing a body defining a mould cavity;   covering a first surface of the mould cavity with a first reinforcement material;   restraining the first reinforcement material relative to the body to restrict movement of the first reinforcement material in the mould cavity;   adding a second reinforcement material to the mould cavity, the second reinforcement material being in contact with the first reinforcement material;   adding molten metal to the mould cavity such that the first reinforcement material and the second reinforcement material become embedded in a continuous metal matrix when the molten metal solidifies.   
     
     
         2 . A method according to  claim 1 , in which the first reinforcement material has a planar profile. 
     
     
         3 . A method according to  claim 2 , in which the first reinforcement material comprises inter-engaging fibres which are entangled, entwined or woven into a sheet-like structure. 
     
     
         4 . A method according to  claim 2 , in which the first reinforcement material comprises at least one elongate member, such as a filament or a braid, wrapped around a former to form a raft-like structure. 
     
     
         5 . A method according to  claim 2 , in which the planar profile of the first reinforcement material has a thickness of at least 1 mm. 
     
     
         6 . A method according to  claim 1 , in which restraining the first reinforcement material relative to the body comprises bonding the first reinforcement material to the body, for example with an adhesive. 
     
     
         7 . A method according to  claim 1 , in which restraining the first reinforcement material relative to the body comprises clamping the first reinforcement material between a first part of the body and a second part of the body. 
     
     
         8 . A method according to  claim 1 , in which restraining the first reinforcement material relative to the body comprises placing the first reinforcement material under tension in the mould cavity. 
     
     
         9 . A method according to  claim 1 , in which the second reinforcement material comprises hollow or porous particles, e.g. ceramic particles. 
     
     
         10 . A method according to  claim 1 , further comprising covering a second surface of the mould cavity with a third reinforcement material. 
     
     
         11 . A method according to  claim 10 , in which the second surface of the mould cavity is opposite the first surface of the mould cavity. 
     
     
         12 . A method according to  claim 10 , in which the third reinforcement material is in contact with the second reinforcement material. 
     
     
         13 . A method according to  claim 10 , further comprising restraining the third reinforcement material relative to the body to restrict movement of the third reinforcement material in the mould cavity. 
     
     
         14 . A method according to  claim 10 , in which the third reinforcement material is the same as the first reinforcement material. 
     
     
         15 . A method according to  claim 1 , further comprising removing a solidified metal matrix composite structure from the mould cavity and cutting the metal matrix composite component from the solidified metal matrix composite structure such that the first reinforcement material is adjacent one external surface of the metal matrix composite component. 
     
     
         16 . A metal matrix composite component comprising a body with an external surface, the body having a surface region adjacent the external surface and a core region spaced from the external surface by the surface region, with a metal matrix extending continuously through the surface region and the core region, wherein the surface region comprises a reinforcement material embedded in the metal matrix, and the core region has a density which is less than that of the surface region. 
     
     
         17 . A metal matrix composite component according to  claim 16 , in which the reinforcement material comprises inter-engaging fibres which are entangled, entwined or woven into a sheet-like structure. 
     
     
         18 . A metal matrix composite component according to  claim 16 , in which the reinforcement material comprises at least one elongate member, such as a filament or a braid, with lengths thereof arranged side-by-side to form a raft-like structure. 
     
     
         19 . A metal matrix composite component according to  claim 16 , in which the reinforcement material has a thickness of at least 1 mm, perhaps at least 1.5 mm, and possibly even at least 2 mm, with the thickness being measured transverse to the external surface and towards the core region. 
     
     
         20 . A metal matrix composite component according to  claim 16 , in which the core region comprises hollow or porous particles, e.g. ceramic particles. 
     
     
         21 . A metal matrix composite component according to  claim 16 , in which the core region has a space frame structure, comprising struts with channels therebetween. 
     
     
         22 . A metal matrix composite component according to  claim 16 , in which the body has a second surface region adjacent the external surface, the second surface region being spaced from the aforementioned surface region by the core region, the second surface region comprising a further reinforcement material embedded in the metal matrix. 
     
     
         23 . A metal matrix composite component according to  claim 16 , further comprising a member protruding from either the surface region or the core region of the body, the member comprising a metal. 
     
     
         24 . A metal matrix composite component according to  claim 23 , in which the member further comprises fibre reinforcement. 
     
     
         25 . A metal matrix composite component according to  claim 23 , in which the member is integrally formed with the metal matrix of the body.