Methods of forming metal matrix composites and metal matrix composites formed thereby

1. A method of forming a metal matrix composite comprising a metal matrix and a fibrous material embedded therein, the method comprising:

bringing a region of the metal matrix into a molten state to form a molten metal matrix by heating and feeding fibrous particles into the metal matrix in the molten state to align at least a substantial majority of the fibrous particles in substantially the same direction,

wherein a Young's modulus of a resultant cooled metal matrix composite is controlled in at least one particular direction and optionally in at least one particular location.

2. The method of claim 1 , wherein the molten metal matrix is formed using one of an electron beam, a laser and a hot gas.

3. The method of claim 2 , wherein the electron beam laser or hot gas is arranged to heat the metal matrix so as to create a molten zone having a relatively hot leading region and a relatively cool trailing region, a forward direction being a direction of travel of the molten zone.

4. The method of claim 3 , wherein a temperature differential between the leading region and trailing region is up to about 1000° C.

5. The method of claim 3 further comprising heating the molten zone in one of a horseshoe, V-shaped and U-shaped heating line, an apex of the heating line being directed in a forward direction, wherein a relatively hot region of the molten zone is provided by the heating line.

6. The method of claim 5 , further comprising multiple-spot heating the molten zone, wherein a relatively hot region of the molten zone is provided by heat spots formed by the multiple-spot heating.

7. The method of claim 1 , further comprising laying at least one continuous fiber into the molten metal matrix.

8. The method of claim 1 , wherein the fibrous particles comprise elongate fibrous particles, the elongate fibrous particles directionally guided into contact with the molten metal matrix such that a majority of the elongate fibrous particles are in a controlled orientation with respect to the molten metal matrix on contact with the molten metal matrix.

9. The method of claim 8 wherein the fibrous particles comprising the elongate fibrous particles have a longitudinal dimension of at least about 0.7 mm in length.

10. The method of claim 8 , wherein the fibrous particles comprising the elongate fibrous particles are contacted by a relatively cool region of the molten zone, and not a relatively hot region of the molten zone.

11. The method of claim 8 , wherein the elongate fibrous particles are guided into contact with the molten metal matrix by passing the elongate fibrous particles in a stream through a channel which is sufficiently narrow such that the elongate fibrous particles are oriented preferentially with their longitudinal axes along a line of travel in the stream directed towards the molten metal matrix.

12. The method of claim 1 , further comprising vibrating the fibrous particles at a sufficient frequency to behave as a fluid.

13. The method of claim 12 , wherein the fibrous particles are vibrated in a hopper-fed chamber.

14. The method of claim 1 , wherein a coefficient of thermal expansion/contraction of the metal matrix is higher than a coefficient of thermal expansion/contraction of the fibrous material.

15. The method of claim 1 , wherein a melting point of the metal matrix is lower than a melting point of the fibrous material.

16. The method of claim 1 , further comprising coating the fibrous material with a volatile organic binder.

17. The method of claim 1 , further comprising coating the fibrous material with a thin coating of the at least one metal of the metal matrix.