Freefall forming of bulk metallic glass feedstock and sheet material

Abstract

The disclosure is directed to freefall methods and apparatuses for preparation of amorphous BMG feedstock and sheet material. In certain aspects, the disclosure relates to methods and apparatuses for contactless formation of BMG feedstock and sheet material via a drop-tower. In certain embodiments, the methods comprise releasing droplets of molten amorphous alloy into a cooled, pressurized chamber of a drop-tower, wherein the droplets traverse the chamber through freefall to thereby form BMG feedstock or sheet material.

1 . A method of forming a metallic glass comprising:
 releasing a droplet of a molten metallic glass-forming alloy from a point above a surface into a drop-tower chamber held at or above atmospheric pressure; and   allowing the droplet to fall through the pressurized drop-tower chamber to form a metallic glass.   
     
     
         2 . The method of  claim 1 , comprising melting the metallic glass-forming alloy using a melting apparatus before the step of releasing the droplet. 
     
     
         3 . The method of  claim 2 , wherein the melting apparatus comprises an induction coil, an RF heater, or a crucible. 
     
     
         4 . The method of  claim 3 , wherein the melting apparatus comprises an induction coil. 
     
     
         5 . The method of  claim 3 , wherein melting apparatus comprises an RF heater. 
     
     
         6 . The method of  claim 3 , wherein melting apparatus comprises a crucible. 
     
     
         7 . The method of  claim 2 , wherein the melting apparatus is in fluid communication with the pressurized drop-tower chamber. 
     
     
         8 . The method of  claim 1 , wherein the chamber contains an inert gas. 
     
     
         9 . The method of  claim 8 , wherein the inert gas is selected from argon, helium, and a combination thereof. 
     
     
         10 . The method of  claim 1 , wherein the metallic glass-forming alloy is selected from a zirconium-based alloy, titanium-based alloy, platinum-based alloy, palladium-based alloy, gold-based alloy, silver-based alloy, copper-based alloy, iron-based alloy, nickel-based alloy, aluminum-based alloy, and molybdenum-based alloy. 
     
     
         11 . The method of  claim 10 , wherein the metallic glass-forming alloy is a platinum-based alloy. 
     
     
         12 . The method of  claim 11 , wherein the platinum-based alloy comprises Pt, Cu, Ni, and Al. 
     
     
         13 . An drop-tower apparatus comprising:
 a melting apparatus configured to melt a metallic glass-forming alloy;   a droplet forming in fluid communication with the melting apparatus;   a pressurized drop-tower chamber operably associated with the droplet forming component in a vertical orientation.   
     
     
         14 . The apparatus of  claim 13 , wherein the melting apparatus is selected from an induction coil, an RF heater, or a crucible. 
     
     
         15 . The method of  claim 14 , wherein the melting apparatus comprises an induction coil. 
     
     
         16 . The method of  claim 3 , wherein the melting apparatus comprises an RF heater. 
     
     
         17 . The method of  claim 3 , wherein the melting apparatus comprises a crucible. 
     
     
         18 . The apparatus of  claim 13 , wherein the droplet forming component comprises a nozzle. 
     
     
         19 . The method of  claim 13 , wherein the drop-tower chamber comprises an inert gas. 
     
     
         20 . A method of forming a metallic glass comprising:
 melting a metallic glass-forming alloy in a melting apparatus;   releasing a droplet of the molten metallic glass-forming alloy from a point above a surface into a pressurized drop-tower chamber; and   allowing the droplet to cool while falling through the chamber to form a metallic glass.