NEW Al-Cu-Li-Mg-Ag-Mn-Zr ALLOY FOR USE AS STRUCTURAL MEMBERS REQUIRING HIGH STRENGTH AND HIGH FRACTURE TOUGHNESS

Abstract

An improved aluminum lithium alloy comprising 0.1 to 2.5 wt. % Li, 2.5 to 5.5 wt. % Cu, 0.2 to 1.0 wt. % Mg, 0.2 to 0.8 wt. % Ag, 0.2 to 0.8 wt. % Mn, up to 0.4 wt. % Zr or other grain refiner such as chromium, titanium, hafnium, scandium or vanadium, the balance aluminum. The present alloy exhibits an improved combination of strength and fracture toughness, over any thickness range. The present invention is further directed to methods for preparing and using Al—Li alloys as well as to products comprising the same.

1 . An aluminum alloy having improved strength and fracture toughness comprising: 
 Cu: 2.5-5.5 wt. %    Li: 0.8-2.5 wt. %    Mg: 0.2-1 wt. %    Ag: 0.2-0.8 wt. %    Mn: 0.2-0.8 wt. %    Zr: up to 0.3 wt. % balance A1 and normal and/or inevitable elements and impurities.    
     
     
         2 . An alloy according to  claim 1 , comprising 3 to 4 wt. % copper.  
     
     
         3 . An alloy according to  claim 1 , comprising 0.8 to 1.8 wt. % lithium.  
     
     
         4 . An alloy according to  claim 1 , comprising 0.8 to 1.5 wt. % lithium.  
     
     
         5 . An alloy according to  claim 3 , comprising 0.8 to 1.2 wt. % lithium.  
     
     
         6 . An alloy according to  claim 1 , comprising 0.3 to 0.5 wt. % magnesium.  
     
     
         7 . An alloy according to  claim 1 , comprising 0.3 to 0.5 wt. % silver.  
     
     
         8 . An alloy according to  claim 1 , comprising 0.3 to 0.5 wt. % manganese.  
     
     
         9 . An alloy according to  claim 1 , comprising 0.05 to 0.15% zirconium.  
     
     
         10 . An aluminum alloy having improved strength and fracture toughness comprising: 
 from about 2.5 to 5.5 wt. % copper, from about 0.8 to 2.5 wt. % lithium,    from about 0.2 to 1 wt. % magnesium, from about 0.2 to 0.8 wt. % silver, from about 0.2 to 0.8 wt. % manganese, optionally one or more elements selected from the group consisting of: (i) up to 0.3 wt. % Zr, (ii) up to 0.8 wt. % Cr, (iii) up to 0.12 wt. % Ti, (iv) up to 0.8 wt. % Sc, and (v) up to 0.2 wt. % V.    
     
     
         11 . A rolled product comprising an aluminum alloy according to  claim 10 , with a thickness of at least about 3 inches, exhibiting in a solution heat-treated, quenched, stress-relieved and artificially aged condition, at least one set of properties selected from the group consisting of: 
 (a) UTS (L)>70 ksi (482.6 MPa) and KE (L)>34 ksNinch (37.4 MPaJm),    (b) TYS (L)>65 ksi (448.2 MPa) and K i c (L)>34 ksi″Jinch (37.4 MParlm),    (c) UTS (LT)>70 ksi (482.6 MPa) and K i c (L-T)>27 ksiAlinch (29.7 MPa-Jm),    (d) TYS (LT)>62 ksi (427.5 MPa) and K 1 c (L-T)>26 ksi  q inch (28.6 MPaVm),    (e) UTS (ST)>70 ksi (482.6 MPa) and K i c (S-T)>24 ksi- q inch (26.4 MPaVm) and    (f) TYS (ST)>60 ksi (413.7 MPa) and K i c (S-T)>23 ksiAlinch (25.3 MPajm).    
     
     
         12 . A rolled product comprising an aluminum alloy according to  claim 9 , with a thickness of less than about 3 inches (76.2 mm), exhibiting in a solution heat-treated, quenched, stress-relieved and artificially aged condition at least one set of properties selected from the group consisting of: 
 (a) UTS (L)>76 ksi (524.0 MPa) and K IC  (L)>35 ksi√inch (38.5 MPa√m),    (b) TYS (L)>71 ksi (489.5 MPa) and K IC  (L)>35 ksi√inch (38.5 MPa√m),    (c) UTS (LT)>75 ksi 517.1 MPa) and K IC  (L-T)>29 ksi√inch (31.9 MPa√m),    (d) TYS (LT)>68 ksi (468.8 MPa) and K IC  (L-T)>29 ksi√inch (31.9 MPa√m),    (e) UTS (ST)>76 ksi (524.0 MPa) and K IC  (S-T)>26 ksi√inch (28.6 MPa√m) and    (f) TYS (ST)>65 ksi (448.2 MPa) and K IC  (S-T)>26 ksi√inch (28.6 MPa√m).