Machinable metal-matrix composite and liquid metal infiltration process for making same

A method of manufacturing a metal-matrix composite comprising the steps of:

• providing a colloidal slurry of ceramic particles in a liquid wherein substantially all of said particles have a particle size of no greater than about 1 micron;
• forming a ceramic preform consisting essentially of a substantially uniform distribution of submicron ceramic particles bonded to one another by separating the ceramic particles from the liquid and bonding the particles together at their points of contact;
• disposing said ceramic preform into a mold;
• contacting said ceramic preform with a molten metal
• driving said molten metal into said preform by pressure infiltration so as to cause said molten metal to penetrate into the pores of said preform without disrupting said preform;
• and
• permitting said molten metal to solidify to form a machinable, solid metal-ceramic composite.

A method of manufacturing a machinable metal-matrix composite, comprising the steps of:

• providing a colloidal slurry of ceramic particles in a liquid wherein substantially all of said particles have a particle size no greater than about 1 micron;
• separating the ceramic particles from the liquid to provide a ceramic preform having a substantially uniform distribution of ceramic particles and sintering the ceramic particles to form particle to particle bonds so that said particles are substantially thermally and chemically stable for the time and temperature of the manufacturing method and the environmental conditions of service, said particles further comprising:
• an oxide, boride, nitride, carbide, carbon or a mixture thereof and a compressive strength of at least about 500 psi;
• disposing said ceramic preform into a mold;
• contacting said ceramic preform with a molten metal selected from a group consisting of:
• Al, Li, Be, Pb, Ag, Au, Sn, Mg, Ti, Cu, Zn or a mixture thereof;
• forcing said molten metal into said ceramic preform so as to penetrate into said preform;
• and
• permitting said molten metal to solidify to form a solid metal-ceramic composite which includes a tensile modulus which is at least about 30% greater than the tensile modulus of said metal.