Gold-aluminum glasses bearing rare-earth metals

Abstract

The disclosure provides Au—Al-Rare-Earth metallic glass-forming alloys and metallic glasses comprising various other additions including but not limited to Cu, Pd, Sn and Mg. In certain embodiments, the metallic glasses according to the disclosure satisfy the 18-Karat Gold Alloy Hallmark, and demonstrate colors that include yellow and pink/rose.

What is claimed is: 
     
         1 . An alloy capable of forming a metallic glass, the alloy comprising:
 an atomic fraction of Au in the range of 40 to 90 percent,   an atomic fraction of Al in the range of 0.5 to 40 percent, and   an atomic fraction of RE is in the range of 1 to 20 percent; and   wherein RE is a rare earth metal.   
     
     
         2 . The alloy of  claim 1  wherein RE is selected from Y, Er, Dy and a combination thereof. 
     
     
         3 . The alloy of  claim 1 , wherein the atomic fraction of Al is in the range of 2 to 20 percent. 
     
     
         4 . The alloy of  claim 2 , wherein RE comprises Y in an atomic fraction of 3 to 15 percent. 
     
     
         5 . The alloy of  claim 1 , further comprising an atomic fraction of Cu of up to 20 percent. 
     
     
         6 . The alloy of  claim 1 , further comprising an atomic fraction of Pd of up to 25 percent. 
     
     
         7 . The alloy of  claim 1 , further comprising Sn in an atomic fraction of up to 10 percent. 
     
     
         8 . The alloy of  claim 1 , further comprising Mg in an atomic fraction of up to 20 percent. 
     
     
         9 . The alloy of  claim 1 , further comprising at least one additional element selected from Ag, Pt, Rh, Ir, Fe, Ni, Co, Ru, Cr, Mo, Mn, Ti, Zr, Hf, W, Re, Be, Ca, Si, P, S, Ge, Ga, In, Sb, and Bi, or combinations thereof, in an atomic fraction of up to 10 percent. 
     
     
         10 . The alloy of  claim 1 , wherein the alloy has a critical casting thickness of at least 1 micrometer. 
     
     
         11 . A metallic glass comprising an alloy of  claim 1 . 
     
     
         12 . The metallic glass of  claim 11 , wherein the metallic glass has a glass transition temperature of at least 150° C. 
     
     
         13 . The metallic glass of  claim 11 , wherein the metallic glass has a Vicker's hardness of at least 400 kgf/mm 2 . 
     
     
         14 . The metallic glass of  claim 11 , wherein the metallic glass has a color having CIELAB coordinates with L* in the range of 65 to 120, a* in the range of −5 to 15, and b* in the range of 5 to 40. 
     
     
         15 . A metallic glass-forming alloy having a composition represented by the following formula (subscripts denote atomic percentages):
   Au (100-a-b-c-d) Al a RE b Cu c Pd d      where:   a ranges from 0.5 to 40;   b ranges from 1 to 20;   c is up to 20;   d up to 25; and   wherein RE is a rare earth metal.   
     
     
         16 . The metallic glass-forming alloy of  claim 15 , where a ranges from 2 to 20. 
     
     
         17 . The metallic glass-forming alloy of  claim 15 , where b ranges from 3 to 15. 
     
     
         18 . The metallic glass-forming alloy of  claim 15 , where c ranges from 0.5 to 10. 
     
     
         19 . The metallic glass-forming alloy of  claim 15 , where d ranges from 0.5 to 20. 
     
     
         20 . The metallic glass-forming alloy of  claim 15 , where the weight fraction of Au is at least 75 percent. 
     
     
         21 . The metallic glass-forming alloy of  claim 15 , wherein the alloy has a critical casting thickness of at least 1 micrometer. 
     
     
         22 . A metallic glass comprising an alloy of  claim 15 . 
     
     
         23 . The metallic glass of  claim 22 , wherein the metallic glass has a glass transition temperature of at least 150° C. 
     
     
         24 . The metallic glass of  claim 22 , wherein the metallic glass has a Vicker's hardness of at least 400 kgf/mm 2 . 
     
     
         25 . The metallic glass of  claim 22 , wherein the metallic glass has a color having CIELAB coordinates with L* in the range of 65 to 120, a* in the range of −5 to 15, and b* in the range of 5 to 40. 
     
     
         26 . A method of producing a metallic glass comprising:
 melting an alloy comprising:
 an atomic fraction of Au in the range of 40 to 90 percent, 
 an atomic fraction of Al in the range of 0.5 to 40 percent, and 
 an atomic fraction of RE is in the range of 1 to 20 percent; and 
 wherein RE is a rare earth metal into a molten state; and 
   quenching the melt at a cooling rate sufficiently high to prevent crystallization of the alloy.