Bulk nickel-cobalt-based glasses bearing chromium, tantalum, phosphorus and boron

Abstract

Ni—Co—Cr—Ta—P—B alloys and metallic glasses with controlled ranges are provided. The alloys demonstrate a combination of good glass forming ability, high toughness, and high stability of the supercooled liquid. The disclosed alloys are capable of forming metallic glass rods of diameters at least 3 mm and up to about 8 mm or greater. Certain alloys with good glass forming ability also have high notch toughness approaching 100 MPa m 1/2 , and stability of the supercooled liquid approaching 60° C.

What is claimed is: 
     
         1 . An alloy capable of forming a metallic glass represented by the following formula (subscripts denote atomic percentages):
   Ni (100-a-b-c-d-e) Co a Cr b Ta c P d B e      
       where:
 a ranges from 0.5 to 40, b ranges from 3 to 11, c ranges from 1.5 to 4, d ranges from 14 to 17.5, and e ranges from 2 to 5, and 
 wherein the alloy has a critical rod diameter of at least 3 mm. 
 
     
     
         2 . The alloy of  claim 1  wherein c is determined by x+y·b, where x is between 1.5 and 2 and y is between 0.1 and 0.15. 
     
     
         3 . The alloy of  claim 1  wherein a ranges from 0.5 to 30, b ranges from 8 to 10.5, c ranges from 2.25 to 3.75, d ranges from 15.5 to 17, e ranges from 2.5 to 4, and wherein the critical rod diameter of the alloy is at least 5 mm. 
     
     
         4 . The alloy of  claim 1  wherein a ranges from 0.5 to 15, b ranges from 8.5 to 10, c ranges from 2.5 to 3.5, d ranges from 15.75 to 16.75, e ranges from 2.75 to 3.75, and wherein the critical rod diameter of the alloy is at least 6 mm. 
     
     
         5 . The alloy of  claim 1  wherein a ranges from 0.5 to 30, b ranges from 6 to 8, c ranges from 2 to 3.5, d ranges from 15.5 to 17, e ranges from 2.5 to 4, and wherein the critical rod diameter of the alloy is at least 5 mm. 
     
     
         6 . The alloy of  claim 1  wherein a ranges from 0.5 to 5, b ranges from 6.5 to 7.5, c ranges from 2.25 to 3.25, d ranges from 15.75 to 16.75, e ranges from 2.75 to 3.75, and wherein the critical rod diameter of the alloy is at least 6 mm. 
     
     
         7 . The alloy of  claim 1  wherein the difference between the crystallization temperature Tx and the glass transition temperature Tg, ΔTx=Tx−Tg, measured at heating rate of 20 K/min, is at least 42° C. 
     
     
         8 . The alloy of  claim 1  wherein the difference between the crystallization temperature Tx and the glass transition temperature Tg, ΔTx=Tx−Tg, measured at heating rate of 20 K/min, is at least 50° C. 
     
     
         9 . The alloy of  claim 1  wherein up to 2 atomic percent of Cr is substituted by Fe, Mn, W, Mo, Ru, Re, Cu, Pd, Pt, or combinations thereof. 
     
     
         10 . The alloy of  claim 1  wherein up to 2 atomic percent of Ni is substituted by Fe, Mn, W, Mo, Ru, Re, Cu, Pd, Pt, or combinations thereof. 
     
     
         11 . The alloy of  claim 1  wherein up to 1.5 atomic percent of Ta is substituted by Nb, V, or combinations thereof. 
     
     
         12 . A metallic glass comprising an alloy of  claim 1 . 
     
     
         13 . The metallic glass of  claim 12  wherein a ranges from 0.5 to 15, b ranges from 8.5 to 10, c ranges from 2.5 to 3.5, d ranges from 15.75 to 16.75, e ranges from 2.75 to 3.75; wherein the critical rod diameter of the alloy is at least 6 mm; and wherein the notch toughness is at least 55 MPa m 1/2 . 
     
     
         14 . The metallic glass of  claim 12  wherein a ranges from 0.5 to 5, b ranges from 6.5 to 7.5, c ranges from 2.25 to 3.25, d ranges from 15.75 to 16.75, e ranges from 2.75 to 3.75; wherein the critical rod diameter of the alloy is at least 6 mm; and wherein the notch toughness is at least 80 MPa m 1/2 . 
     
     
         15 . The metallic glass of  claim 12  wherein a ranges from 0.5 to 10, b ranges from 8.5 to 10, c ranges from 2.5 to 3.5, d ranges from 15.75 to 16.75, e ranges from 2.75 to 3.75; wherein the critical rod diameter of the alloy is at least 6 mm; and wherein the notch toughness is at least 60 MPa m 1/2 . 
     
     
         16 . The metallic glass of  claim 12  wherein a ranges from 0.5 to 3, b ranges from 6.5 to 7.5, c ranges from 2.25 to 3.25, d ranges from 15.75 to 16.75, e ranges from 2.75 to 3.75; wherein the critical rod diameter of the alloy is at least 7 mm; and wherein the notch toughness is at least 90 MPa m 1/2 . 
     
     
         17 . A method of producing the metallic glass of  claim 12  comprising:
 melting the alloy into a molten state; and 
 quenching the melt at a cooling rate sufficiently rapid to prevent crystallization of the alloy. 
 
     
     
         18 . The method of  claim 17 , further comprising fluxing the melt with a reducing agent prior to quenching. 
     
     
         19 . The method of  claim 18 , wherein the reducing agent is boron oxide. 
     
     
         20 . The method of  claim 17 , wherein the melt prior to quenching is heated to at least 1100° C.