Melt fluxing method for improved toughness and glass-forming ability of metallic glasses and glass-forming alloys

Abstract

A method of fluxing the melt of metallic glass forming alloys is provided. Alloys fluxed according to the disclosed methods demonstrate a critical rod diameter that does not vary by more than 60% when varying the melt overheating. Moreover, metallic glasses produced from alloys fluxed according to the disclosed methods demonstrate notch toughness that does not vary by more than 30% when varying the melt overheating. Furthermore, a method by which used feedstock is purified such that its toughness and glass forming ability is restored for reuse is also disclosed. Recycled feedstock purified according to the disclosed method demonstrates critical rod diameter that is at least 70% of the critical rod diameter of the as-formed alloy. Also, metallic glasses produced from recycled feedstock demonstrate notch toughness of at least 70% of the notch toughness of a metallic glass produced from the as-formed alloy.

1 . A method of producing a metallic glass, comprising:
 melting an alloy in contact with a fluxing agent by heating to a fluxing temperature above the liquidus temperature, T liquidus  of the alloy;   allowing the alloy melt to interact with the fluxing agent melt while in contact at the fluxing temperature to form a fluxed alloy;   cooling the fluxed alloy to a temperature below the solidus temperature of the fluxed alloy;   wherein the metallic glass formed of the fluxed alloy has a notch toughness that does not vary by more than 30% when varying the melt overheating temperature.   
     
     
         2 . The method of  claim 1 , wherein the fluxed alloy is cooled to a temperature below the glass-transition temperature at a cooling rate sufficiently rapid to prevent crystallization of the alloy to form a metallic glass. 
     
     
         3 . The method of  claim 1  further comprising:
 heating the fluxed alloy to a temperature above T liquidus  to form a fluxed alloy melt; 
 cooling the fluxed alloy melt to a temperature below the glass-transition temperature at a cooling rate sufficiently rapid to prevent crystallization of the alloy to form a metallic glass. 
 
     
     
         4 . The method of  claim 1 , wherein the metallic glass formed of the fluxed alloy has a notch toughness that does not vary by more than 20% when varying the melt overheating temperature. 
     
     
         5 . The method of  claim 1 , wherein the alloy melt interacts with the fluxing agent melt while in contact at the fluxing temperature for a fluxing time of at least 60 seconds. 
     
     
         6 . The method of  claim 1 , wherein the fluxing temperature is at least 100° C. above the liquidus temperature, T liquidus . 
     
     
         7 . The method of  claim 1 , wherein the critical rod diameter of the fluxed alloy does not vary by more than 60% when varying the melt overheating temperature. 
     
     
         8 . The method of  claim 1 , wherein the metal with the highest atomic fraction in the alloy is Pd, Pt, Au, Ni, Fe, Co, or Cu. 
     
     
         9 . The method of  claim 1 , wherein the alloy comprises a metalloid, semi-metal, or non-metal, where a metalloid, semi-metal, or non-metal is P, Si, Ge, C, B, or combinations thereof. 
     
     
         10 . The method of  claim 1 , wherein the fluxing agent comprises boron and oxygen. 
     
     
         11 . A method of recycling a scrap alloy capable of producing a metallic glass, comprising:
 heating the scrap alloy in contact with a fluxing agent to a fluxing temperature above the liquidus temperature, T liquidus ;   allowing the scrap alloy melt to interact with the fluxing agent melt while in contact at the fluxing temperature to form a fluxed scrap alloy melt;   cooling the fluxed scrap alloy melt to a temperature below the glass transition of the alloy to obtain a recycled alloy having a critical rod diameter of at least 70% of the critical rod diameter of the alloy in its as-formed state; and   wherein the metallic glass produced from the recycled alloy has a notch toughness of at least 70% of the notch toughness of the metallic glass produced from the alloy in its as-formed state.   
     
     
         12 . The method of  claim 11 , wherein the scrap alloy has undergone at least two shaping cycles. 
     
     
         13 . The method of  claim 11 , wherein the recycled alloy has a critical rod diameter of at least 80% of the critical rod diameter of the as-formed alloy. 
     
     
         14 . The method of  claim 11 , wherein the metallic glass produced has a notch toughness of at least 80% of the notch toughness of the metallic glass produced from the alloy in its as-formed state. 
     
     
         15 . The method of  claim 11 , wherein the recycled alloy has an oxygen concentration that does not exceed the oxygen concentration of the as-formed alloy by more than 40%. 
     
     
         16 . The method of  claim 11 , wherein the metal with the highest atomic fraction in the alloy is Pd, Pt, Au, Ni, Fe, Co, or Cu. 
     
     
         17 . The method of  claim 11 , wherein the alloy comprises a metalloid, semi-metal, or non-metal, where a metalloid, semi-metal, or non-metal is P, Si, Ge, C, B, or combinations thereof. 
     
     
         18 . The method of  claim 11 , wherein the fluxing agent comprises boron and oxygen. 
     
     
         19 . A recycled alloy having a critical rod diameter of at least 70% of the critical rod diameter of the alloy in its as-formed state, the recycled alloy produced by a process comprising:
 heating a scrap alloy in contact with a fluxing agent to a fluxing temperature above the liquidus temperature, T liquidus ;   allowing the scrap alloy melt to interact with the fluxing agent melt while in contact at the fluxing temperature;   cooling the fluxed scrap alloy melt to a temperature below the glass transition temperature of the alloy to obtain the recycled alloy having the critical rod diameter of at least 70% of the critical rod diameter of the alloy in its as-formed state.   
     
     
         20 . A metallic glass article formed comprising the recycled alloy of  claim 19 , wherein the metallic glass article produced from the recycled alloy has a notch toughness of at least 70% of the notch toughness of a metallic glass produced from the alloy in its as-formed state.