Thermoplastic forming of cold rolled alloys

Abstract

The disclosure is directed to methods of forming glassy alloys. A glassy alloy is cold rolled at a temperature less than Tg of the glassy alloy to form a flattened glassy alloy. Then, the cold rolled glassy alloy is thermoplastically formed at a temperature above Tg of the glassy alloy. In certain embodiments, the flattened glassy alloy may have one or more shear bands and/or micro-cracks, and the thermoplastic forming may heal the shear bands and/or micro-cracks. The resulting glassy alloy may thereby have reduced or eliminated shear bands and/or micro-cracks.

What is claimed: 
     
         1 . A method of forming a glassy alloy comprising:
 cold rolling a glassy alloy feedstock at a temperature less than the glass transition temperature (Tg) of the glassy alloy feedstock to form a flattened glassy alloy; and   thermoplastically forming the flattened glassy alloy at a temperature at or above Tg of the glassy alloy feedstock to form the glassy alloy.   
     
     
         2 . The method of  claim 1 , wherein the glassy alloy has a thickness that does not vary by more than about 10% after cold rolling and thermoplastic forming. 
     
     
         3 . The method of  claim 1 , wherein the flattened glassy alloy has a thickness that is within about 0.04 mm of the thickness of the glassy alloy. 
     
     
         4 . The method of  claim 1 , wherein the flattened glass alloy comprises one or more shear bands. 
     
     
         5 . The method of  claim 4 , wherein the thermoplastic forming heals the one or more shear bands in the flattened glassy alloy to form a substantially shear band-free glassy alloy. 
     
     
         6 . The method of  claim 5 , wherein less than 2% of the total surface area of the substantially shear band-free glassy alloy comprises shear bands. 
     
     
         7 . The method of  claim 1 , wherein the glassy alloy is selected from a nickel (Ni) based glassy alloy, an iron (Fe) based glassy alloy, a copper (Cu) based glassy alloy, a zinc (Zi) based glassy alloy, a zirconium (Zr) based glassy alloy, a gold (Au)-based glassy alloy, a platinum (Pt) based glassy alloy, and a palladium (Pd) based glassy alloy. 
     
     
         8 . The method of  claim 1 , wherein the flattened glassy alloy is thermoplastically formed for 15 to 90 seconds. 
     
     
         9 . The method of  claim 1 , wherein the glassy alloy is a Pt-based glassy alloy. 
     
     
         10 . The method of  claim 9 , wherein the flattened glassy alloy is thermoplastically formed for 15 to 30 seconds. 
     
     
         11 . A glassy alloy part comprised of a glassy alloy and formed from a combination of cold rolling and thermoplastic forming, wherein the glassy alloy part has a variation in thickness of less than about 10% and is substantially free of shear bands. 
     
     
         12 . The glassy alloy part of  claim 11 , wherein less than 2% of the total surface area of the glassy alloy part comprises shear bands. 
     
     
         13 . The glassy alloy part of  claim 11 , wherein the glassy alloy is selected from a nickel (Ni) based glassy alloy, an iron (Fe) based glassy alloy, a copper (Cu) based glassy alloy, a zinc (Zi) based glassy alloy, a zirconium (Zr) based glassy alloy, a gold (Au)-based glassy alloy, a platinum (Pt) based glassy alloy, and a palladium (Pd) based glassy alloy. 
     
     
         14 . The glassy alloy part of  claim 11 , wherein the glassy alloy is a Pt-based glassy alloy. 
     
     
         15 . The glass alloy part of  claim 11 , wherein the glass alloy part exhibits no structural relaxation embrittlement. 
     
     
         16 . A method of determining the presence of a crystalline metal in a glassy alloy comprising:
 cold rolling a glassy alloy feedstock at a temperature less than Tg of the glassy alloy to form a flattened glassy alloy; and   determining the presence of cracks radiating from a portion of the flattened glassy alloy, the portion of the flattened glassy alloy corresponding to the presence of the crystalline metal in the flattened glassy alloy.   
     
     
         17 . The method of  claim 16 , wherein the glassy alloy is selected from a nickel (Ni) based glassy alloy, an iron (Fe) based glassy alloy, a copper (Cu) based glassy alloy, a zinc (Zi) based glassy alloy, a zirconium (Zr) based glassy alloy, a gold (Au)-based glassy alloy, a platinum (Pt) based glassy alloy, and a palladium (Pd) based glassy alloy. 
     
     
         18 . The method of  claim 16 , further comprising thermoplastically forming the flattened glassy alloy at a temperature at or above Tg of the glassy alloy feedstock to form the glassy alloy. 
     
     
         19 . The method of  claim 16 , wherein the glassy alloy has a thickness that does not vary by more than about 10% after cold rolling and thermoplastic forming. 
     
     
         20 . The method of  claim 19 , wherein the thermoplastic forming heals cracks radiating from a portion of the flattened glassy alloy.