Bio-co-cr-mo alloy with ion elution suppressed by structure control, and process for producing same

Abstract

This invention provides a technique for rendering bio-toxicity such as allergy toxicity derived from Ni trace impurity, i.e., nickel toxicity, which is unavoidably present in a bio-Co—Cr—Mo alloy or an Ni-free stainless steel alloy unharmful, characterized in that an element selected from the group consisting of the group 4, 5 and 13 elements of the periodic table, particularly an element selected from the group consisting of the group 4 elements of the periodic table, is added to the alloy composition. The additive element is preferably an element selected from the group consisting of zirconium and titanium, more preferably zirconium.

1 - 12 . (canceled) 
     
     
         13 . A method for suppressing ion elution in a bio-Co—Cr—Mo alloy, said method for suppressing ion elution from a bio-Co—Cr—Mo alloy characterized in comprising adjusting an alloy structure in controlled fashion to cause enrichment with an ε HCP phase structure. 
     
     
         14 . The method for suppressing ion elution from a bio-Co—Cr—Mo alloy according to  claim 13 , characterized in that adjusting an alloy structure in a bio-Co—Cr—Mo alloy in controlled fashion adds an element or compound selected from the group that includes elements in groups 4, 5, and 13 of the periodic table, lanthanide elements, misch metals, and Mg to an alloy composition. 
     
     
         15 . The method for suppressing ion elution from a bio-Co—Cr—Mo alloy according to  claim 14 , characterized in that the additive element is selected from the group that includes Mg, Al, Ti, Zr, and Nb. 
     
     
         16 . The method for suppressing ion elution from a bio-Co—Cr—Mo alloy according to  claim 14 , characterized in that the additive element is an element selected from the group that includes elements in group 4 of the periodic table. 
     
     
         17 . The method for suppressing ion elution from a bio-Co—Cr—Mo alloy according to  claim 16 , characterized in that the additive element is selected from the group that includes zirconium and titanium. 
     
     
         18 . The method for suppressing ion elution from a bio-Co—Cr—Mo alloy according to  claim 16 , characterized in that the additive element is zirconium. 
     
     
         19 . The method for suppressing ion elution from a bio-Co—Cr—Mo alloy according to  claim 14 , characterized in that
 a nickel content in the alloy composition is (1) about 1.0 wt % or less, (2) about 0.5 wt % or less, (3) about 0.002 wt % or less, (4) the order of 100 ppm or less, or (5) on the order of several hundred parts per million or less; and 
 the alloy composition is an alloy in which Ni is unavoidably present. 
 
     
     
         20 . The method for suppressing ion elution from a bio-Co—Cr—Mo alloy according to  claim 14 , characterized in performing a heat treatment at a temperature of 600° C. to 1250° C. 
     
     
         21 . The method for suppressing ion elution from a bio-Co—Cr—Mo alloy according to  claim 14 , characterized in
 (i) melting an alloy composition or heat treating an alloy composition at a temperature of 1000° C. or higher, and then rapidly cooling the alloy composition; or 
 (ii) heat treating an alloy composition for a long period of time at a temperature of approximately 1000° C. or lower and in a temperature range of at least 550 to 650° C. 
 
     
     
         22 - 28 . (canceled)