Abstract: Provided is a sintered gear (1) as a sintered machine part, which is formed of a sintered compact (M?) and which rotates in conjunction with an input of a load from another member onto a radially outer surface while sliding with respect to a shaft (S) inserted along an inner periphery, in which the sintered compact (M?) includes an inner layer (2) containing Cu and an outer layer (3) sintered together with the inner layer (2) under a state of being held in contact with the inner layer (2), in which the outer layer (3) includes, as main components, Fe, Cu, and Sn as a low-melting-point metal, and a metal structure of the outer layer (3) includes, as main constituents, Fe structures and Cu—Sn alloy structures, which exist at a grain boundary of the Fe structures and bind the Fe structures to each other.

Abstract: Provided is a gear (1) (machine part), including a sintered compact obtained by sintering a green compact of raw material powder (10) that contains as a main raw material iron-based alloy powder containing molybdenum and has 0.1 to 0.8 mass % of carbon powder blended therein, the gear (1) (machine part) including a hardened layer (8) formed through heat treatment after the sintering, and having a true density ratio of 97% or more and less than 100%.

Abstract: Provided is a gear (1) (machine part), including a sintered compact obtained by sintering a green compact of raw material powder (10) that contains as a main raw material iron-based alloy powder containing molybdenum and has 0.1 to 0.8 mass % of carbon powder blended therein, the gear (1) (machine part) including a hardened layer (8) formed through heat treatment after the sintering, and having a true density ratio of 97% or more and less than 100%.