(57) The present invention relates to lead free, free cutting copper alloys and methods
of their manufacture. In particular, the present invention is directed to a lead-free,
free-cutting copper alloy which comprises 70 to 80 percent, by weight, of copper;
1.8 to 3.5 percent, by weight, of silicon; and at least one element selected from
among 0.3 to 3.5 percent, by weight, of tin, 1.0 to 3.5 percent, by weight, of aluminium,
and 0.02 to 0.25 percent, by weight, of phosphorous; and the remaining percent, by
weight, of zinc and wherein the metal structure of the free cutting copper alloy has
at least one phase selected from the γ (gamma) phase and the κ (kappa) phase.
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