Silver alloy compositions

Abstract

Fire-scale resistant, work-hardenable-jewelry, silver-alloy compositions having desirable properties of reduced fire scale, reduced porosity, oxide formation and reduced grain size relative to traditional sterling silver alloys while providing improved work hardening performance. These compositions contain at least 86% by weight silver, 0-5-7.5% by weight copper, 0.07-6% by weight of a mixture of zinc an silicon with silicon being present in an amount from about 0.02 to about 2.0% by weight, and from about 0.01 to no more than 2.0% by weight germanium.

1 . A fire scale resistant, work hardenable jewelry silver alloy composition comprising: 
 at least 86% by weight silver;    0.5-7.5% by weight copper    0.07-6% by weight of a mixture of zinc and silicon wherein said silicon is present in an amount of from about 0.02 to about 2.0% by weight; and    from about 0.01 to no more than 2.0% by weight germanium.    
   
   
       2 . The silver alloy composition of  claim 1  wherein said silver is present in an amount at least 92.5% by weight.  
   
   
       3 . The silver alloy composition of  claim 1  wherein said copper is present in an amount of from about 2.0 to about 4.0% by weight.  
   
   
       4 . The silver alloy composition of  claim 1  that includes zinc in an amount of from about 2.0 to about 4.0% by weight.  
   
   
       5 . The silver alloy composition of  claim 1  wherein said germanium is present in an amount of from about 0.04 to no more than 2.0% by weight.  
   
   
       6 . The silver alloy composition of  claim 1  that includes an additive selected from the group consisting of indium, boron and a mixture of indium and boron in an amount of up to about 3.5% by weight.  
   
   
       7 . The silver alloy composition of  claim 1  wherein said mixture comprises up to about 2% by weight boron and up to about 1.5% by weight indium.  
   
   
       8 . The silver alloy composition of  claim 1  that includes tin amount up to about 6% by weight.  
   
   
       9 . The silver alloy composition of  claim 8  wherein said tin is present in an amount of from about 0.25 to about 6% by weight.  
   
   
       10 . A fire scale resistant, work hardenable jewelry silver alloy composition comprising: 
 81-95.409% by weight silver;    0.5-6% by weight copper;    0.05-5% by weight zinc;    0.02-2% by weight silicon;    0.01-2% by weight boron;    0.01-1.5% by weight indium; and,    0.01—no more than 2.0% by weight germanium.    
   
   
       11 . A fire scale resistant, work hardenable jewelry silver alloy composition comprising: 
 75-99.159% by weight silver;    0.5-6% by weight copper;    0.05-5% by weight zinc;    0.02-2% by weight silicon;    0.01-2% by weight boron;    0.01-1.5% by weight indium;    0.25-6% by weight tin; and,    0.01—no more than 2% by weight germanium.