Methods and apparatus for rejuvenation of amorphous alloys and micro-alloying

Abstract

The disclosure provides a method of modifying a surface of a metallic glass. The method includes applying an electron beam within an energy band to a crystalline metal portion at a surface zone of the metallic glass. The method also includes changing the crystalline metal portion to an amorphous portion at the surface zone of the metallic glass, while a bulk region embedded in the metallic glass under the surface zone remains crystalline.

What is claimed is: 
     
         1 . A method of modifying a crystalline metal portion in a metallic glass comprising:
 applying an electron beam within an energy band to the crystalline metal portion at a surface zone of the metallic glass; and   changing the crystalline metal portion to an amorphous portion at the surface zone of the metallic glass, while a bulk metal region embedded in the metallic glass under the surface zone remains crystalline.   
     
     
         2 . The method of  claim 1 , wherein the surface zone has a depth up to 100 μm. 
     
     
         3 . The method of  claim 1 , further comprising selecting the energy band of the electron beam by filtering out electrons having energy above an upper threshold energy. 
     
     
         4 . The method of  claim 3 , comprising filtering out the electrons having energy below a lower threshold energy. 
     
     
         5 . The method of  claim 1 , wherein the electron beam is a pulsed electron beam. 
     
     
         6 . The method of  claim 1 , wherein the surface zone has the same chemical composition as the bulk region. 
     
     
         7 . The method of  claim 1 , wherein the metallic glass is selected from a group consisting of a Zr-based metallic glass, a Pt-based metallic glass, a Pd-based metallic glass, a Au-based metallic glass, a Ag-based metallic glass, a Ni-based metallic glass, and a Fe-based metallic glass. 
     
     
         8 . A method of micro-alloying an element on a metallic glass comprising:
 placing a target material onto a portion of a surface of the metallic glass; and   alloying the target material with the metallic glass to form an amorphous surface zone with a depth of up to 5 μm in the metallic glass.   
     
     
         9 . The method of  claim 8 , wherein the amorphous surface zone has a different composition from the metallic glass. 
     
     
         10 . The method of  claim 8 , wherein the target material comprises copper. 
     
     
         11 . The method of  claim 8 , wherein the metallic glass comprises a Zr-based metallic glass, a Pt-based metallic glass, a Pd-based metallic glass, a Au-based metallic glass, a Ag-based metallic glass, a Ni-based metallic glass, and a Fe-based metallic glass. 
     
     
         12 . The method of  claim 8 , further comprising applying an electron beam to the surface of the metallic glass, before alloying the target material. 
     
     
         13 . The method of  claim 12 , wherein the electron beam is a pulsed electron beam. 
     
     
         14 . A method of modifying a surface of a metallic glass comprising:
 applying an electron beam to a localized crystalline metal portion at the surface of the metallic glass to heat the metallic glass at a temperature below the melting temperature of the metallic glass; and   rejuvenating the localized crystalline metal portion into an amorphous portion.   
     
     
         15 . The method of  claim 14 , wherein the amorphous portion has a depth of up to 100 μm. 
     
     
         16 . A metal comprising a metallic coating diffused into a surface of a metallic glass substrate to a depth of at least 50 microns. 
     
     
         17 . The metal according to  claim 16 , wherein the metallic coating is diffused into the metallic glass substrate to a depth of at least 75 microns. 
     
     
         18 . The metal according to  claim 16 , wherein the metallic coating is diffused into the metallic glass substrate to a depth of at least 90 microns. 
     
     
         19 . A metal comprising a metallic coating diffused into a metallic glass substrate to a depth up to 5 microns. 
     
     
         20 . An electronic device comprising a housing, the housing comprising the metal according to  claim 19 .