Abstract A mechanical mixture of selected powders is subjected to compressive forces to define a pre-compact, the pre-compact then being subjected to liquid phase sintering for producing a raw alloy steel product which is more economical and has enhanced physical properties, particularly tensile strength as compared to sintered compacts produced by the prior art to date. The improvement in physical properties and processing technique results principally from the use of a mechanical mixture consisting of a base iron powder and a coated alloyed additive powder having selected alloying ingredients (such as manganese, nickel, molybdenum, in an iron-carbon system); the particles of the alloyed powder have a thin flash coating of a low melting metal, such as copper, to control carbon diffusion into the base iron powder during liquid phase sintering.
A sintered iron based alloy composition, comprising: a matrix of iron-carbon particles sintered together in intimate contact, each iron-carbon particle having at least an interior peripheral zone containing dissolved and diffused metal alloying ingredients, said ingredients consisting essentially of copper and at least one of chromium and manganese in an amount of 2-10% by weight, and said iron-carbon particles also each having a gradient proceeding from an outer exterior region rich in said metal alloying ingredients, and said particles having a carbon content of 0.4-.68% by weight.
Claim 2
Dependent Claim
87 words
A sintered iron based alloy composition, comprising: a matrix of iron-carbon particles sintered together in intimate contact, each iron-carbon particle having at least an interior peripheral zone containing dissolved and diffused metal alloying ingredients, said ingredients consisting essentially of copper and at least one of chromium and manganese in an amount of 2-10% by weight, and said iron-carbon particles also each having a gradient proceeding from an outer exterior region rich in said metal alloying ingredients, and said particles having a carbon content of 0.4-.68% by weight.
Claim 3
Dependent Claim
11 words
The composition of claim 1, which contains about .05% copper dissolved.
Claim 4
Dependent Claim
44 words
The composition as in claim 1, in which the alloying content thereof is no less than 2% by weight, and said composition exhibiting a strength of at least 70,000 psi in tension, as sintered hardness of RB 40 and a density of 6.5-6.6 g./cc.