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 - 21 . (canceled) 
     
     
         22 . A bio-Co—Cr—Mo alloy, characterized in that
 an alloy structure in the bio-Co—Cr—Mo alloy is enriched with an ε HCP phase structure; and 
 ion elution from the alloy is suppressed or reduced. 
 
     
     
         23 . The alloy according to  claim 22 , characterized in that 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 is added to a bio-Co—Cr—Mo alloy composition. 
     
     
         24 . The alloy according to  claim 22 , 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) at least on 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.   
     
     
         25 . The alloy according to  claim 22 , characterized in that a heat treatment at a temperature of 600° C. to 1250° C. is performed. 
     
     
         26 . The alloy according to  claim 22 , characterized in that
 (i) an alloy composition is melted or heat treated at a temperature of 1000° C. or higher, and then rapidly cooled; or   (ii) an alloy composition is heat treated 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.   
     
     
         27 . A medical device manufactured from the bio-Co—Cr—Mo alloy according to  claim 22 . 
     
     
         28 . A medical device manufactured by subjecting the bio-Co—Cr—Mo alloy according to  claim 22  to a process selected from the group that includes quenching, metal gas atomization, mechanical alloying, liquid quenching, hot extrusion, hot rolling, hot drawing, and forging.