Coating composition comprising chromium and aluminum and coatings formed using the same

Abstract

This disclosure generally relates to coating compositions comprising chromium and aluminum and coatings formed using the same, and more particularly to bond coat compositions and coatings for use in various gas turbine applications. In one aspect, a material composition comprises M, Cr, and Al, wherein M is one or more of Ni, Co, and Fe. The material composition is configured to form a BCC ordered phase and a disordered metallic phase of either a BCC or FCC crystal structure.

1 . A feedstock material, comprising:
 a composition that comprises, in weight percent (wt. %):
 nickel: 18-31; 
 cobalt: 18-31; 
 iron: 18-31; 
 chromium: 16-27; and 
 aluminum: 2-13; and 
   a microstructure that comprises a B2 ordered phase and a disordered metallic phase,   wherein the disordered metallic phase comprises a BCC crystal structure or an FCC crystal structure,   wherein, under equilibrium conditions, a formation temperature of the B2 ordered phase is greater than a formation temperature of the disordered metallic phase by between 0 K and 150 K, and   wherein at least 85% of grains in the microstructure have a size of 100 nm or smaller.   
     
     
         2 . The feedstock material of  claim 1 , wherein the composition further comprises 0.25-1 wt. % yttrium. 
     
     
         3 . (canceled) 
     
     
         4 . The feedstock material of  claim 1  wherein the formation temperature of the B2 ordered phase is greater than the formation temperature of the disordered metallic phase by between 25 K and 80 K under equilibrium thermodynamic conditions. 
     
     
         5 . The feedstock material of  claim 1 , wherein the microstructure comprises 40 mole % or more of the B2 ordered phase under thermodynamic equilibrium conditions. 
     
     
         6 . The feedstock material of  claim 1 , wherein the microstructure further comprises 5 mole % or greater of one or more oxidation resistant phases under thermodynamic equilibrium conditions, wherein the one or more oxidation resistant phases include a compound of a metal that has higher oxidation resistance compared to the metal and wherein the one or more oxidation resistant phases comprises chromium carbide. 
     
     
         7 . (canceled) 
     
     
         8 . A coating comprising:
 a composition that comprises, in weight percent (wt. %):
 nickel: 18-31; 
 cobalt: 18-31; 
 iron: 18-31; 
 chromium: 16-27; and 
 aluminum: 2-13; and 
   a microstructure that comprises a B2 ordered phase and a disordered metallic phase, wherein:
 the disordered metallic phase comprises a BCC crystal structure or an FCC crystal structure, 
 under equilibrium conditions, a formation temperature of the B2 ordered phase is greater than a formation temperature of the disordered metallic phase by less than 150 K, and 
 at least 85% of grains in the microstructure have a size of 100 nm or smaller when the coating is formed by cooling from a liquid state at a rate between 5° C./sec and 20° C./sec. 
   
     
     
         9 . (canceled) 
     
     
         10 . The coating of  claim 8 , wherein the microstructure comprises at least 40 mole % of the B2 ordered phase. 
     
     
         11 . The coating of  claim 8 , wherein the microstructure further comprises 5 volume % or greater of one or more oxidation resistant phases, wherein the one or more oxidation resistant phases include a compound of a metal that has higher oxidation resistance compared to the metal and wherein the one or more oxidation resistant phases comprises chromium carbide. 
     
     
         12 . (canceled) 
     
     
         13 . (canceled) 
     
     
         14 . The coating of  claim 8 , wherein the coating is formed on a Ni-based superalloy. 
     
     
         15 . The coating of  claim 8 , wherein the coating has applied thereon a thermal barrier coating. 
     
     
         16 . The coating of  claim 15 , wherein the thermal barrier coating comprises yttria-stabilized zirconia. 
     
     
         17 . The coating of  claim 8 , wherein the composition further comprises 0.25-1 wt. % yttrium. 
     
     
         18 . A bond coat material comprising:
 M, Cr, and Al, wherein M is one or more of Ni, Co, and Fe; and   a microstructure that comprises a B2 ordered phase and a disordered metallic phase,   wherein the disordered metallic phase comprises a BCC or FCC crystal structure,   wherein, under equilibrium conditions, a formation temperature of the B2 ordered phase is greater than formation temperature of the disordered metallic phase by between 0 K and 150 K, and   wherein at least 85% of grains in the microstructure are 100 nm in size or smaller when solidified from a liquid state at a rate between 5° C./second and 20° C./second.   
     
     
         19 . (canceled) 
     
     
         20 . The bond coat material of  claim 18 , wherein the B2 ordered phase and the disordered metallic phase have a cosine similarity of greater than 85%. 
     
     
         21 . The bond coat material of  claim 18 , wherein the B2 ordered phase comprises greater than 40 mole % of the microstructure. 
     
     
         22 . The bond coat material of  claim 18 , wherein the microstructure further comprises 10 mole % or greater of one or more oxidation resistant phases, wherein the one or more oxidation resistant phases include a compound of a metal that has higher oxidation resistance compared to the metal and wherein the one or more oxidation resistant phases comprises chromium carbide. 
     
     
         23 . (canceled) 
     
     
         24 . The bond coat material of  claim 18 , wherein the bond coat material comprises in weight % (wt. %):
 nickel: 18-31;   cobalt: 18-31;   iron: 18-31;   chromium: 16-27; and   aluminum: 2-13.   
     
     
         25 . The bond coat material of  claim 18 , wherein, upon cooling from the liquid state during the formation of the bond coat material, the B2 ordered phase precipitates first, followed by the disordered metallic phase. 
     
     
         26 . The bond coat material of  claim 25 , further comprising:
 0.1-1 wt. % yttrium.   
     
     
         27 . The bond coat material of  claim 18 , wherein the bond coat material is formed between a Ni-based superalloy and a thermal barrier coating. 
     
     
         28 . (canceled) 
     
     
         29 . (canceled) 
     
     
         30 . (canceled) 
     
     
         31 . (canceled) 
     
     
         32 . (canceled) 
     
     
         33 . (canceled) 
     
     
         34 . (canceled)