Other

Masahisa Miyahara

Akira Fujiki

Motohiro Suzuki

Hiroyuki Nishiyama

Masato Otsuki

Makoto Yoshida

Haruo Okamoto

An internal gear oil pump made of Al alloys having less mutual damage property and superior wear resistance is provided. The internal gear oil pump has a casing with a gear compartment, a drive gear, and a driven gear, all of which are the structural members of the internal gear oil pump. The casing is constituted of an Al-alloy casting. The drive gear and the driven gear are constituted of a hot plastic working material of Al&mdash;Si alloy powder. The hot plastic working material is constituted of an Al&mdash;Si alloy having a structure in which unit crystal phases are dispersed in a base matrix by 10 to 40 area percent. by the structural observation with an optical microscope, the unit. crystal phases being harder than the base matrix. The base matrix is constituted of an Al&mdash;Si alloy which contains, on weight basis, 10% to 18% Si, 4% to 8% Fe, 1% to 3% Ni, 1% to 3% Cr, and the balance being Al and incidental impurities. The alloy has a structure in which ultrafine grains of intermetallic compounds and Si are dispersed in the matrix. The unit crystal phases are constituted of an Al&mdash;Si alloy which contains, on weight basis, 25% to 40% Si, 1% to 3% Fe, 2% to 6% Ni, 0.3% to 2% Cr, and the balance being Al and incidental impurities. The alloy has a structure in which ultrafine grains of intermetallic compounds and Si, and primary Si crystal grains are dispersed in the matrix of the unit crystal phases.

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Omiya, Japan

Masahisa Miyahara