Lead-free copper alloys

Abstract

Disclosed is a lead-free copper alloy with superior properties as compared to currently available lead-free copper alloys which can be produced at lower costs than currently available lead-free copper alloys. The lead-free copper alloy uses a novel combination of tin, nickel and zinc along with selenium and bismuth to avoids the problems associated with leaded copper alloys, while maintaining physical properties comparable to traditional leaded copper alloys. In one embodiment, the lead-free copper alloy described contains from about 7.5 to 10.0 percent by weight zinc, from about 0.8 to 1.5 percent by weight nickel, from about 1.6 to 2.2 percent by weight bismuth, from about 0.04 to 0.35 percent by weight selenium, from about 2.2 to 3.0 percent by weight tin and up to about 0.3 percent by weight iron (maximum), the balance, apart from impurities, being copper. In an alternate embodiment, the lead-free copper alloy described contains from about 5 to 7.5 percent by weight zinc, from about 1.0 to 1.5 percent by weight nickel, from about 1.5 to 2.6 percent by weight bismuth, from about 0.04 to 0.35 percent by weight selenium, from about 5 to 6 percent by weight tin and up to about 0.3 percent by weight iron (maximum), the balance, apart from impurities, being copper.

What is claimed:  
     
         1 . A machinable, lead-free copper alloy comprising: 
 a. from about 7.5 to 10.0 percent by weight zinc;    b. from about 0.8 to 1.5 percent by weight nickel;    c. from about 1.6 to 2.2 percent by weight bismuth;    d. from about 0.04 to 0.35 percent by weight selenium; and    e. the balance, apart from impurities, being copper.    
     
     
         2 . The alloy of  claim 1  where the copper is from about 85.5 to 88.0 percent by weight.  
     
     
         3 . The alloy of  claim 1  further comprising from about 2.2 to 3.0 percent by weight tin.  
     
     
         4 . The alloy of  claim 3  further comprising up to about 0.3 percent by weight iron.  
     
     
         5 . The alloy of  claim 4  further comprising up to about 0.2 percent by weight lead.  
     
     
         6 . The alloy of  claim 1  where the zinc is from about 5.0 to 7.5 percent by weight, the nickel is from 1.0 to 1.5 percent by weight and the bismuth is from about 1.6 to 2.6 percent by weight.  
     
     
         7 . The alloy of  claim 6  where the copper is from 85.0 to 88.0 percent by weight.  
     
     
         8 . The alloy of  claim 6  further comprising from about 5.0 to 6.0 percent by weight tin.  
     
     
         9 . The alloy of  claim 8  further comprising up to about 0.3 percent by weight iron.  
     
     
         10 . The alloy of  claim 9  further comprising up to about 0.2 percent by weight lead.  
     
     
         11 . A machinable, lead-free copper alloy comprising: 
 a. from about 7.5 to 10.0 percent by weight zinc;    b. from about 0.8 to 1.5 percent by weight nickel;    c. an addition of bismuth and selenium, where the bismuth/selenium weight ratio ranges from about 4.5 to 1 to about 55 to 1; and    d. the balance, apart from impurities, being copper.    
     
     
         12 . The alloy of  claim 11  where the copper is from about 85.5 to 88.0 percent by weight.  
     
     
         13 . The alloy of  claim 11  further comprising from about 1.2 to 3.0 percent by weight tin.  
     
     
         14 . The alloy of  claim 13  further comprising up to about 0.3 percent by weight iron.  
     
     
         15 . The alloy of  claim 4  further comprising up to about 0.2 percent by weight lead.  
     
     
         16 . The alloy of  claim 11  where the zinc is from about 5.0 to 7.5 percent by weight, the nickel is from 1.0 to 1.5 percent by weight and the bismuth/selenium weight ratio ranges from about 4.5 to 1 to about 65 to 1.  
     
     
         17 . The alloy of  claim 16  where the copper is from 85.0 to 88.0 percent by weight.  
     
     
         18 . The alloy of  claim 16  further comprising from about 5.0 to 6.0 percent by weight tin.  
     
     
         19 . The alloy of  claim 18  further comprising up to about 0.3 percent by weight iron.  
     
     
         20 . The alloy of  claim 19  further comprising up to about 0.2 percent by weight lead.  
     
     
         21 . The alloy of  claim 5  where the copper concentration is about 86.1 percent by weight, the tin concentration is about 2.4 percent by weight, the zinc concentration is about 7.9 percent by weight, the nickel concentration is about 1.1 percent by weight, the bismuth concentration is about 2.0 percent by weight, the selenium concentration is about 0.35 percent by weight, the iron concentration is about 0.07 percent by weight and the lead concentration is about 0.11 percent by weight.  
     
     
         22 . The alloy of  claim 10  where the copper concentration is about 85.3 percent by weight, the tin concentration is about 5.1 percent by weight, the zinc concentration is about 6.3 percent by weight, the nickel concentration is about 1.0 percent by weight, the bismuth concentration is about 1.9 percent by weight, the selenium concentration is about 0.30 percent by weight, the iron concentration is about 0.03 percent by weight and the lead concentration is about 0.11 percent by weight.