Patent ID: 8062582

Claim:
A method of forming a metal part comprising the steps of: (i) providing a metal powder composition comprising a blend of primary metal particles of iron, pre-alloyed iron, aluminum, pre-alloyed aluminum, copper or pre-alloyed copper, said primary metal particles having an outer surface comprising a metal oxide, and an organics package that is capable of being spread onto the outer surface of the primary metal particles, the organics package comprising an organic lubricant, an organic acid and/or an organic compound other than the lubricant or organic acid that leaves a carbon residue on the outer surface of the primary metal particles subsequent to a delubing step; (ii) compacting the metal powder composition within a die cavity to form a green compact, wherein the organics package is spread onto the outer surface of the primary metal particles in the green compact; (iii) delubing the green compact in an inert atmosphere; and (iv) sintering the delubed green compact to a peak sintering temperature at a heat up rate of 60° F./min or higher to form the metal part, wherein the metal oxides on the surface of the primary metal particles in the green compact are removed in situ in a reaction with the organic acid, lubricant and/or the carbon residue from the organic compound other than the lubricant or organic acid at a temperature below which liquid phase bonding and/or solid state diffusion occurs in the sintering step, and wherein the metal part has a sintered density that is ≧26% of a theoretical density for all metallic constituents of the metal powder composition immediately after the sintering step and prior to any further post-sintering densification steps.