Machinable metal matrix composite and method for making the same

A metal-matrix composite comprising:

• a primary metal component consisting essentially of 6061 aluminum and alloys thereof and comprising 50-80 vol % of the metal-matrix composite;
• and
• a secondary ceramic component comprising calcined ceramic particles consisting essentially of alumina (Al2O3) and magnesium oxide (MgO),
• wherein the ceramic particles have an average particle size of between 0.35 and 0.90 microns;
• wherein the ceramic particles are prepared from a ceramic precursor mixture consisting essentially of
• Alumina (Al2O3)
• 41.37
• wt %
• Magnesia (MgO)
• 0.02-7.00
• wt %
• Carbon black
• 9.47
• wt %
• Graphite
• 13.03
• wt %
• Organic binders
• 2.15
• wt %
• Deionized Water
• 33.96
• wt %
• and further wherein the ceramic precursor mixture is subjected to a thermal treatment process to obtain a ceramic particle preform,
• wherein the ceramic particles are uniformly distributed throughout the primary metal component to form the metal-matrix composite,
• wherein the ceramic particles comprise 20-50 vol % of the metal-matrix composite,
• wherein the ceramic particles are chemically stable in the primary metal component at a temperature above a melting point of the primary metal component,
• wherein the metal-matrix composite has a first tensile modulus, the primary metal component has a second tensile modulus, the first tensile modulus and the second tensile modulus having a ratio of at least 1.3:1, and
• wherein the metal-matrix composite is machinable with a high speed steel (HSS).