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

摘要

Metal-matrix composites and methods for producing these composites are provided. The manufacturing methods include providing a ceramic preform having a uniform distribution of ceramic particles sintered to one another. The particles include an average particle size of no greater than about 3 microns, and at least one half of the volume of the preform is occupied by porosity. The preform is then disposed into a mold and contacted by molten metal. The molten metal is then forced into the pores of the preform and permitted to solidify to form a solid metal-matrix composite. This composite is machinable with a high-speed steel (HSS) bit for greater than about 1 minute without excessive wear occurring to the bit. This invention preferably employs metal-matrixes including Al, Li, Be, Pb, He, Au, Sn, Mg, Ti, Cu, and Zn. Preferred ceramics include oxides, borides, nitrides, carbides, carbon, or a mixture thereof. Inert gas pressures of less than about 3,000 psi can be used to easily infiltrate the preforms.