抄録
As the substitute of lead bronze, a metallic structure control technique applying eutectoid transformation was employed to develop lead-free or low lead copper alloys for bearings. Considerable lamellar eutectoid structures made of copper-tin based intermetallic compound and copper solid solution containing fine bismuth precipitates were dispersed in as-cast alloys by means of an alloy design technique. The lamellar eutectoid structure was formed between primary α dendrite arms after transformation of a part of β phase without producing granular δ phases. In the range of tin content from 4 to 12mass%, the amount of the eutectoid structure was linearly increased with the tin content. Above 12mass%, the amount of the eutectoid was decreased with increasing tin content. Alloys containing the lamellar eutectoid structure showed higher anti-seizing and higher abrasion resistances than those of the lead bronze LBC3, suggesting that the formation of the laminate composite structure and precipitation of fine bismuth particles produce excellent wear-resistance.
