| 摘要 |
PROBLEM TO BE SOLVED: To provide a non-lead free cutting copper alloy having satisfactory machinability in industrial level without containing lead. SOLUTION: The non-lead free cutting copper alloy contains copper of 70-78 percent by mass, aluminum of 3.5-7.0 percent by mass and zinc for the rest, and has a metallic structure comprisingαphase and a dispersed fine mixture phase includingγphase. The mixture phase is composed of a fineγphase precipitated throughβphase transformation,αphase and a nontransformed residual fineβphase. For area ratio, theαphase is contained by 95-60 %, and theγphase is contained by 40-20%. Additionally the copper alloy contains boron of 0.01-0.1 percent by mass or vanadium of 0.05-0.5 percent by mass, as required. COPYRIGHT: (C)2003,JPO
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