High-hardness precious metal alloy and method for producing the same

Abstract

A precious metal alloy mainly including a quaternary alloy of Pt, Au, Ni, and Pd includes 7.5% by atom or more and 72.5% by atom or less of Pt, 5.5% by atom or more and 62.5% by atom or less of Au, 3% by atom or more and 62.5% by atom or less of Ni, and 0.15% by atom or more and 38% by atom or less of Pd. When respective concentrations (% by atom) of Pt, Au, Ni, and Pd represent CPt, CAu, CNi, CPd, the value of the following first compositional parameter z1 is 0.5 or more and 2.88 or less and also the concentration CPd of Pd satisfies CPd≤z2 with respect to the following second compositional parameter z2. A present inventive precious metal alloy is a high-hardness precious metal alloy to which a strengthening mechanism by spinodal decomposition and/or ordering is applied.z⁢1=(CPt×CAu×CNi)/10000[Expression⁢1]z⁢2=a×(CAu)3+b×(CAu)2+c×CAu+d[Expression⁢2]coefficients a, b, c, and d are the following numerical values.a=0.00077, b=−0.102,c=3.607, d=1.722

1 . A precious metal alloy comprising 7.5% by atom or more and 72.5% by atom or less of Pt, 5.5% by atom or more and 62.5% by atom or less of Au, 3% by atom or more and 62.5% by atom or less of Ni, and 0.15% by atom or more and 38% by atom or less of Pd, wherein,
 when respective concentrations (% by atom) of Pt, Au, Ni, and Pd are designated as C Pt , C Au , C Ni , and C Pd , a value of a first compositional parameter z1 represented by the following expression is 0.5 or more and 2.88 or less, and   furthermore the concentration C Pd  of Pd satisfies C Pd ≤z2 with respect to a second compositional parameter z2 represented by the following expression:   
       
         
           
             
               
                 
                   
                     
                       z 
                       ⁢ 
                       1 
                     
                     = 
                     
                       
                         ( 
                         
                           
                             C 
                             Pt 
                           
                           × 
                           
                             C 
                             Au 
                           
                           × 
                           
                             C 
                             Ni 
                           
                         
                         ) 
                       
                       / 
                       10000 
                     
                   
                 
                 
                   
                     [ 
                     
                       Expression 
                       ⁢ 
                           
                       1 
                     
                     ] 
                   
                 
               
             
           
         
         
           
             
               
                 
                   
                     
                       z 
                       ⁢ 
                       2 
                     
                     = 
                     
                       
                         a 
                         × 
                         
                           
                             ( 
                             
                               C 
                               Au 
                             
                             ) 
                           
                           3 
                         
                       
                       + 
                       
                         b 
                         × 
                         
                           
                             ( 
                             
                               C 
                               Au 
                             
                             ) 
                           
                           2 
                         
                       
                       + 
                       
                         c 
                         × 
                         
                           C 
                           Au 
                         
                       
                       + 
                       d 
                     
                   
                 
                 
                   
                     [ 
                     
                       Expression 
                       ⁢ 
                           
                       2 
                     
                     ] 
                   
                 
               
             
           
         
       
       coefficients a, b, c, and d are the following numerical values.
 a=0.00077, b=−0.102, 
 c=3.607, d=1.722 
 
     
     
         2 . The precious metal alloy according to  claim 1 , comprising 10% by atom or more and 67.5% by atom or less of Pt, 5.85% by atom or more and 40% by atom or less of Au, 10% by atom or more and 60% by atom or less of Ni, and 0.2% by atom or more and 34% by atom or less of Pd. 
     
     
         3 . The precious metal alloy according to  claim 1 , comprising 17.5% by atom or more and 60.5% by atom or less of Pt, 6.25% by atom or more and 30% by atom or less of Au, 15% by atom or more and 57.5% by atom or less of Ni, and 0.75% by atom or more and 24.5% by atom or less of Pd. 
     
     
         4 . The precious metal alloy according to  claim 1 , wherein a material texture comprises a modulated texture by spinodal decomposition. 
     
     
         5 . The precious metal alloy according to  claim 1 , wherein a material texture comprises an ordered phase. 
     
     
         6 . A method for producing the precious metal alloy defined in  claim 1 , comprising the steps of:
 providing a precious metal alloy comprising 7.5% by atom or more and 72.5% by atom or less of Pt, 5.5% by atom or more and 62.5% by atom or less of Au, 3% by atom or more and 62.5% by atom or less of Ni, and 0.15% by atom or more and 38% by atom or less of Pd;   executing a solution treatment of heating the precious metal alloy at a temperature of 850° C. or more and 1350° C. or less and then quenching the precious metal alloy; and   executing an aging treatment of heating the precious metal alloy after the solution treatment, at a temperature of 300° C. or more and 700° C. or less.   
     
     
         7 . A method for producing the precious metal alloy defined in  claim 1 , comprising the steps of:
 providing a precious metal alloy comprising 7.5% by atom or more and 72.5% by atom or less of Pt, 5.5% by atom or more and 62.5% by atom or less of Au, 3% by atom or more and 62.5% by atom or less of Ni, and 0.15% by atom or more and 38% by atom or less of Pd; and   executing a heat treatment of heating the precious metal alloy at a temperature of 850° C. or more and 1350° C. or less and then cooling the precious metal alloy, wherein   the cooling in the heat treatment step is a treatment involving quenching in a temperature region of not more than a melting point and 600° C. or more and cooling at a cooling rate of 2.5° C./s or less in a temperature region of less than 600° C.   
     
     
         8 . The precious metal alloy according to  claim 2 , wherein a material texture comprises a modulated texture by spinodal decomposition. 
     
     
         9 . The precious metal alloy according to  claim 3 , wherein a material texture comprises a modulated texture by spinodal decomposition. 
     
     
         10 . The precious metal alloy according to  claim 2 , wherein a material texture comprises an ordered phase. 
     
     
         11 . The precious metal alloy according to  claim 3 , wherein a material texture comprises an ordered phase. 
     
     
         12 . The precious metal alloy according to  claim 4 , wherein a material texture comprises an ordered phase. 
     
     
         13 . A method for producing the precious metal alloy defined in  claim 2 , comprising the steps of:
 providing a precious metal alloy comprising 7.5% by atom or more and 72.5% by atom or less of Pt, 5.5% by atom or more and 62.5% by atom or less of Au, 3% by atom or more and 62.5% by atom or less of Ni, and 0.15% by atom or more and 38% by atom or less of Pd;   executing a solution treatment of heating the precious metal alloy at a temperature of 850° C. or more and 1350° C. or less and then quenching the precious metal alloy; and   executing an aging treatment of heating the precious metal alloy after the solution treatment, at a temperature of 300° C. or more and 700° C. or less.   
     
     
         14 . A method for producing the precious metal alloy defined in  claim 3 , comprising the steps of:
 providing a precious metal alloy comprising 7.5% by atom or more and 72.5% by atom or less of Pt, 5.5% by atom or more and 62.5% by atom or less of Au, 3% by atom or more and 62.5% by atom or less of Ni, and 0.15% by atom or more and 38% by atom or less of Pd;   executing a solution treatment of heating the precious metal alloy at a temperature of 850° C. or more and 1350° C. or less and then quenching the precious metal alloy; and   executing an aging treatment of heating the precious metal alloy after the solution treatment, at a temperature of 300° C. or more and 700° C. or less.   
     
     
         15 . A method for producing the precious metal alloy defined in  claim 4 , comprising the steps of:
 providing a precious metal alloy comprising 7.5% by atom or more and 72.5% by atom or less of Pt, 5.5% by atom or more and 62.5% by atom or less of Au, 3% by atom or more and 62.5% by atom or less of Ni, and 0.15% by atom or more and 38% by atom or less of Pd;   executing a solution treatment of heating the precious metal alloy at a temperature of 850° C. or more and 1350° C. or less and then quenching the precious metal alloy; and   executing an aging treatment of heating the precious metal alloy after the solution treatment, at a temperature of 300° C. or more and 700° C. or less.   
     
     
         16 . A method for producing the precious metal alloy defined in  claim 5 , comprising the steps of:
 providing a precious metal alloy comprising 7.5% by atom or more and 72.5% by atom or less of Pt, 5.5% by atom or more and 62.5% by atom or less of Au, 3% by atom or more and 62.5% by atom or less of Ni, and 0.15% by atom or more and 38% by atom or less of Pd;   executing a solution treatment of heating the precious metal alloy at a temperature of 850° C. or more and 1350° C. or less and then quenching the precious metal alloy; and   executing an aging treatment of heating the precious metal alloy after the solution treatment, at a temperature of 300° C. or more and 700° C. or less.   
     
     
         17 . A method for producing the precious metal alloy defined in  claim 2 , comprising the steps of:
 providing a precious metal alloy comprising 7.5% by atom or more and 72.5% by atom or less of Pt, 5.5% by atom or more and 62.5% by atom or less of Au, 3% by atom or more and 62.5% by atom or less of Ni, and 0.15% by atom or more and 38% by atom or less of Pd; and   executing a heat treatment of heating the precious metal alloy at a temperature of 850° C. or more and 1350° C. or less and then cooling the precious metal alloy, wherein   the cooling in the heat treatment step is a treatment involving quenching in a temperature region of not more than a melting point and 600° C. or more and cooling at a cooling rate of 2.5° C./s or less in a temperature region of less than 600° C.   
     
     
         18 . A method for producing the precious metal alloy defined in  claim 3 , comprising the steps of:
 providing a precious metal alloy comprising 7.5% by atom or more and 72.5% by atom or less of Pt, 5.5% by atom or more and 62.5% by atom or less of Au, 3% by atom or more and 62.5% by atom or less of Ni, and 0.15% by atom or more and 38% by atom or less of Pd; and   executing a heat treatment of heating the precious metal alloy at a temperature of 850° C. or more and 1350° C. or less and then cooling the precious metal alloy, wherein   the cooling in the heat treatment step is a treatment involving quenching in a temperature region of not more than a melting point and 600° C. or more and cooling at a cooling rate of 2.5° C./s or less in a temperature region of less than 600° C.   
     
     
         19 . A method for producing the precious metal alloy defined in  claim 4 , comprising the steps of:
 providing a precious metal alloy comprising 7.5% by atom or more and 72.5% by atom or less of Pt, 5.5% by atom or more and 62.5% by atom or less of Au, 3% by atom or more and 62.5% by atom or less of Ni, and 0.15% by atom or more and 38% by atom or less of Pd; and   executing a heat treatment of heating the precious metal alloy at a temperature of 850° C. or more and 1350° C. or less and then cooling the precious metal alloy, wherein   the cooling in the heat treatment step is a treatment involving quenching in a temperature region of not more than a melting point and 600° C. or more and cooling at a cooling rate of 2.5° C./s or less in a temperature region of less than 600° C.   
     
     
         20 . A method for producing the precious metal alloy defined in  claim 5 , comprising the steps of:
 providing a precious metal alloy comprising 7.5% by atom or more and 72.5% by atom or less of Pt, 5.5% by atom or more and 62.5% by atom or less of Au, 3% by atom or more and 62.5% by atom or less of Ni, and 0.15% by atom or more and 38% by atom or less of Pd; and   executing a heat treatment of heating the precious metal alloy at a temperature of 850° C. or more and 1350° C. or less and then cooling the precious metal alloy, wherein   the cooling in the heat treatment step is a treatment involving quenching in a temperature region of not more than a melting point and 600° C. or more and cooling at a cooling rate of 2.5° C./s or less in a temperature region of less than 600° C.