Heat treatable l12 aluminum alloys

Abstract

High temperature heat treatable aluminum alloys that can be used at temperatures from about −420° F. (−251° C.) up to about 650° F. (343° C.) are described. The alloys are strengthened by dispersion of particles based on the L1 2 intermetallic compound Al 3 X. These alloys comprise aluminum; silicon; at least one of scandium, erbium, thulium, ytterbium, and lutetium; and at least one of gadolinium, yttrium, zirconium, titanium, hafnium, and niobium. Magnesium and copper are optional alloying elements.

1 . A method of forming a heat treatable aluminum alloy, the method comprising:
 (a) forming a melt comprising:
 about 4.0 to about 25.0 weight percent silicon; 
 about 0.2 to about 3.0 weight percent magnesium; 
 about 0.5 to about 5.0 weight percent copper; 
 at least one first element selected from the group comprising about 0.1 to about 0.5 weight percent scandium, about 0.1 to about 6.0 weight percent erbium, about 0.1 to about 10 weight percent thulium, about 0.1 to about 15.0 weight percent ytterbium, and about 0.1 to about 12 weight percent lutetium; 
 at least one second element selected from the group comprising about 0.1 to about 4.0 weight percent gadolinium, about 0.1 to about 4.0 weight percent yttrium, about 0.05 to about 1.0 weight percent zirconium, about 0.05 to about 2.0 weight percent titanium, about 0.05 to about 2.0 weight percent hafnium, and about 0.05 to about 1.0 weight percent niobium; and 
 the balance substantially aluminum; 
   (b) solidifying the melt to form a solid body; and   (c) heat treating the solid body.   
     
     
         2 . The method of  claim 1  further comprising:
 refining the structure of the solid body by deformation processing including at least one of: extrusion, forging and rolling. 
 
     
     
         3 . The method of  claim 1 , wherein solidifying comprises a casting process. 
     
     
         4 . The method of  claim 1 , wherein solidifying comprises a rapid solidification process in which the cooling rate is greater than about 10 3 ° C./second including at least one of: powder processing, atomization, melt spinning, splat quenching, spray deposition, cold spray, plasma spray, laser melting and deposition, ball milling, and cryomilling. 
     
     
         5 . The method of  claim 1 , wherein the heat treating comprises:
 solution heat treatment at about 800° F. (426° C.) to about 1100° F. (593° C.) for about thirty minutes to four hours; and   quenching; and   aging at a temperature of about 200° F. (93° C.) to about 600° F. (315° C.) for about two to forty eight hours.