5XXX-LITHIUM ALUMINUM ALLOYS, AND METHODS FOR PRODUCING THE SAME

Info

Publication number: 20140127076
Type: Application
Filed: Feb 26, 2013
Publication Date: May 8, 2014
Applicant: ALCOA INC. (Pittsburgh, PA)
Inventors: Roberto J. Rioja (Murrysville, PA), Francine S. Bovard (Monroeville, PA), Ralph R. Sawtell (Gibsonia, PA)
Application Number: 13/777,709

Abstract

New 5xxx-lithium aluminum alloys and related products are disclosed. The new 5xxx-lithium aluminum alloy may contain from 3.75 to 5.0 wt. % Mg, from 1.6 to 2.3 wt. % Li, and from 0.50 to 2.5 wt. % Zn, among others.

Description

Description

BACKGROUND

Aluminum alloys are useful in a variety of applications. However, improving one property of an aluminum alloy without degrading another property often proves elusive.

SUMMARY OF THE DISCLOSURE

Broadly, the present disclosure relates to new 5xxx-lithium aluminum alloy products having an improved combination of properties. The new 5xxx-lithium aluminum alloy products are made from aluminum alloys containing from 3.75 to 5.0 wt. % magnesium (Mg), from 1.6 to 2.3 wt. % lithium (Li), from 0.50 to 2.5 wt. % zinc (Zn), 0.05 to 0.50 wt. % of a grain structure control element selected from the group consisting of Zr, Sc, Cr, V, Hf, other rare earth elements, and combinations thereof, optionally up to 1.0 wt. % copper (Cu), optionally up to 1.0 wt. % silver (Ag), wherein wt. % Cu+wt. % Ag≦1.15 wt. %, wherein, when the aluminum alloy contains not greater than 0.04 wt. % Cu and not greater than 0.04 wt. % Ag, the aluminum alloy contains at least 0.75 wt. % zinc, optionally up to 0.5 wt. % silicon (Si), optionally up to 1.0 wt. % manganese (Mn), optionally up to 0.25 wt. % Fe, optionally up to 0.15 wt. % Ti, the balance being aluminum, other elements and impurities, wherein the aluminum alloy contains not greater than 0.10 wt. % of any one of the other elements, and wherein the aluminum alloy contains not greater than 0.35 wt. % total of the other elements. The new 5xxx-lithium aluminum alloys may realize an improved combination of properties, such as an improved combination of two or more of strength, fracture toughness, density, fatigue crack growth, and/or corrosion resistance, among others. The new 5xxx-lithiurn aluminum alloys may be used in aerospace and defense applications, among others.

5xxx aluminum alloys are aluminum alloys having magnesium as the predominate alloying element other than aluminum. The new 5xxx-lithium aluminum alloys of the present patent application are 5xxx aluminum alloys having 3.75 to 5.0 wt. % Mg, from 1.6-2.3 wt. % Li, and from 0.5 to 2.5 wt. % Zn, among others, as described below. The new 5xxx-lithium aluminum alloy products are generally in the form of wrought products, and may be produced by casting the new 5xxx-lithium alloy, after which it is homogenized, then hot worked to an intermediate gauge or a final gauge, then optionally cold worked, then solution heat treated and quenched, then optionally cold worked, and then optionally artificially aged. Thus, the new 5xxx-lithium aluminum alloy products are generally in the T3 or T8 temper, such tempers being known to those skilled in the art and defined by the Aluminum Association. The above hot working step may be completed by rolling, extruding, or forging to produce a sheet or plate, an extrusion, or a forging, respectively.

The new 5xxx-lithium aluminum alloy products generally contain from 3.75 to 5.0 wt. % Mg. In one embodiment, a new 5xxx-lithium aluminum alloy product contains at least 4.0 wt. % Mg. In another embodiment, a new 5xxx-lithium aluminum alloy product contains at least 4.1 wt. % Mg. In yet another embodiment, a new 5xxx-lithium aluminum alloy product contains at least 4.2 wt. % Mg. In another embodiment, a new 5xxx-lithium aluminum alloy product contains at least 4.3 wt. % Mg. In one embodiment, a new 5xxx-lithium aluminum alloy product contains not greater than 4.9 wt. % Mg. In another embodiment, a new 5xxx-lithium aluminum alloy product contains not greater than 4.8 wt. % Mg. In yet another embodiment, a new 5xxx-lithium aluminum alloy product contains not greater than 4.7 wt. % Mg. In another embodiment, a new 5xxx-lithium aluminum alloy product contains not greater than 4.6 wt. % Mg.

The new 5xxx-lithium aluminum alloy products generally contain from 1.60 to 2.30 wt. % Li. In one embodiment, a new 5xxx-lithium aluminum alloy product contains at least 1.65 wt. % Li. In another embodiment, a new 5xxx-lithium aluminum alloy product contains at least 1.70 wt. % Li. In yet another embodiment, a new 5xxx-lithium aluminum alloy product contains at least 1.75 wt. % Li. In one embodiment, a new 5xxx-lithium aluminum alloy product contains not greater than 2.20 wt. % Li. In another embodiment, a new 5xxx-lithium aluminum alloy product contains not greater than 2.10 wt. % Li.

The new 5xxx-lithium aluminum alloy products generally contain from 0.5 to 2.50 wt. % Zn. In one embodiment, a new 5xxx-lithium aluminum alloy product contains at least 0.60 wt. % Zn. In another embodiment, a new 5xxx-lithium aluminum alloy product contains at least 0.70 wt. % Zn. In yet another embodiment, a new 5xxx-lithium aluminum alloy product contains at least 0.80 wt. % Zn. In another embodiment, a new 5xxx-lithium aluminum alloy product contains at least 0.90 wt. % Zn. In yet another embodiment, a new 5xxx-lithium aluminum alloy product contains at least 1.00 wt. % Zn. In one embodiment, a new 5xxx-lithium aluminum alloy product contains not greater than 2.25 wt. % Zn. In another embodiment, a new 5xxx-lithium aluminum alloy product contains not greater than 2.00 wt. % Zn.

The new 5xxx-lithium aluminum alloy products may optionally contain up to 1.0 wt. % copper (Cu). In embodiments where copper is used, the new 5xxx-lithium aluminum alloy products contain at least 0.05 wt. % Cu. In one embodiment, the new 5xxx-lithium aluminum alloy products contain at least 0.15 wt. % Cu. In another embodiment, the new 5xxx-lithium aluminum alloy products contain at least 0.25 wt. % Cu. In yet another embodiment, the new 5xxx-lithium aluminum alloy products contain at least 0.30 wt. % Cu. In one embodiment, the new 5xxx-lithium aluminum alloy products contain not greater than 0.90 wt. % Cu. In another embodiment, the new 5xxx-lithium aluminum alloy products contain not greater than 0.80 wt. % Cu. In yet another embodiment, the new 5xxx-lithium aluminum alloy products contain not greater than 0.70 wt. % Cu. In another embodiment, the new 5xxx-lithium aluminum alloy products contain not greater than 0.60 wt. % Cu. In some embodiments copper is present as an impurity, and in these embodiments the new 5xxx-lithium aluminum alloy products contain not greater than 0.04 wt. % Cu.

The new 5xxx-lithium aluminum alloy products may optionally contain up to 1.0 wt. % silver (Ag). In embodiments where silver is used, the new 5xxx-lithium aluminum alloy products contain at least 0.05 wt. % Ag. In one embodiment, the new 5xxx-lithium aluminum alloy products contain at least 0.15 wt. % Ag. In another embodiment, the new 5xxx-lithium aluminum alloy products contain at least 0.25 wt. % Ag. In yet another embodiment, the new 5xxx-lithium aluminum alloy products contain at least 0.30 wt. % Ag. In one embodiment, the new 5xxx-lithium aluminum alloy products contain not greater than 0.90 wt. % Ag. In another embodiment, the new 5xxx-lithium aluminum alloy products contain not greater than 0.80 wt. % Ag. In yet another embodiment, the new 5xxx-lithium aluminum alloy products contain not greater than 0.70 wt. % Ag. In another embodiment, the new 5xxx-lithium aluminum alloy products contain not greater than 0.60 wt. % Ag. In some embodiments silver is present as an impurity, and in these embodiments the new 5xxx-lithium aluminum alloy products contain not greater than 0.04 wt. % Ag.

When the new 5xxx-lithium aluminum alloy products contain copper and silver, the new 5xxx-lithium aluminum alloy products contain not greater than 1.15 wt. %. Cu+Ag (i.e., (wt % Cu)+(wt. % Ag)≦1.15 wt. %). In one embodiment, the new 5xxx-lithium aluminum alloy products contain not greater than 1.10 wt. % Cu+Ag. In another embodiment, the new 5xxx-lithium aluminum alloy products contain not greater than 1.05 wt. % In another embodiment, the new 5xxx-lithium aluminum alloy products contain not greater than 1.00 wt. % Cu+Ag.

In embodiments where copper and/or or silver are used, the new 5xxx-lithium aluminum alloy products generally contain at least 0.15 wt. % Cu+Ag (i.e., (wt. % Cu)+(wt. % Ag)≧0.15 wt. %), where at least one of copper and silver is present. In one embodiment, the new 5xxx-lithium aluminum alloy products contain at least 0.25 wt. % Cu+Ag. In another embodiment, the new 5xxx-lithium aluminum alloy products contain at least 0.35 wt. % Cu+Ag. In yet another embodiment, the new 5xxx-lithium aluminum alloy products contain at least 0.40 wt. % Cu+Ag. In another embodiment, the new 5xxx-lithium aluminum alloy products contain at least 0.45 wt. % Cu+Ag. In yet another embodiment, the new 5xxx-lithium aluminum alloy products contain at least 0.50 wt. % Cu+Ag.

When copper and/or silver are used, the alloys may include less zinc. For example, when the alloys include at least 0.05 wt. % Cu or at least 0.05 wt. % Ag, the alloys may include as low as 0.50 wt. % zinc. When copper and/or silver is not used, the alloys require higher zinc. For example, when the alloys include not greater than 0.04 wt. % Cu (i.e., Cu as an impurity) and not greater than 0.04 wt. % Ag (i.e., Ag as an impurity), the alloys include at least 0.75 wt. % zinc.

The new 5xxx-lithium aluminum alloy products may optionally contain up to 0.5 wt. % silicon (Si). In embodiments where silicon is used, the new 5xxx-lithium aluminum alloy products contain at least 0.05 wt. % Si. In one embodiment, the new 5xxx-lithium aluminum alloy products contain not greater than 0.35 wt. % Si. In another embodiment, the new 5xxx-lithium aluminum alloy products contain not greater than 0.25 wt. % Si. In some embodiments silicon is present as an impurity, and in these embodiments the new 5xxx-lithium aluminum alloy products contain not greater than 0.04 wt. % Si.

The new 5xxx-lithium aluminum alloy products may optionally contain up to 1.0 wt. % manganese (Mn), In embodiments where manganese is used, the new 5xxx-lithium aluminum alloy products contain at least 0.05 wt. % Mn. In one embodiment, the new 5xxx-lithium aluminum alloy products contain at least 0.20 wt. % Mn. In another embodiment, the new 5xxx-lithium aluminum alloy products contain at least 0.30 wt. % Mn. In yet another embodiment, the new 5xxx-lithium aluminum alloy products contain at least 0.40 wt. % Mn. In one embodiment, the new 5xxx-lithium aluminum alloy products contain not greater than 0.75 wt. % Mn. In another embodiment, the new 5xxx-lithium aluminum alloy products contain not greater than 0.50 wt. % Mn. In some embodiments manganese is present as an impurity, and in these embodiments the new 5xxx-lithium aluminum alloy products contain not greater than 0.04 wt. % Mn.

The new 5xxx-lithium aluminum alloy products may include 0.05 to 0.50 wt. % of at least one grain structure control element selected from the group consisting of zirconium (Zr), scandium (Sc), chromium (Cr), vanadium (V) and/or hafnium (HO, and/or other rare earth elements, and such that the utilized grain structure control element(s) is/are maintained below maximum solubility. As used herein, “grain structure control element” means elements or compounds that are deliberate alloying additions with the goal of forming second phase particles, usually in the solid state, to control solid state grain structure changes during thermal processes, such as recovery and recrystallization. For purposes of the present patent application, grain structure control elements include Zr, Sc, Cr, V, Hf, other rare earth elements, and combinations thereof, but excludes Mn.

The amount of grain structure control material utilized in an alloy is generally dependent on the type of material utilized for grain structure control and/or the alloy production process. In one embodiment, the grain structure control element is Zr, and the alloy includes from 0.05 wt. % to 0.20 wt. % Zr. In another embodiment, the alloy includes from 0.05 wt. % to 0.15 wt. % Zr. In another embodiment, the alloy includes 0.07 to 0.14 wt. % Zr. In another embodiment, the alloy includes 0.08-0.13 wt. % Zr. In one embodiment, the aluminum alloy includes at least 0.07 wt. % Zr. In another embodiment, the aluminum alloy includes at least 0.08 wt. % Zr. In one embodiment, the aluminum alloy includes not greater than 0.18 wt. % Zr. In another embodiment, the aluminum alloy includes not greater than 0.15 wt. % Zr. In another embodiment, the aluminum alloy includes not greater than 0.14 wt. % Zr. In another embodiment, the aluminum alloy includes not greater than 0.13 wt. % Zr.

The new 5xxx-lithium aluminum alloy products may include up to 0.15 wt. % Ti cumulatively for ingot grain refining and/or other purposes. Grain refiners are inoculants or nuclei to seed new grains during solidification of the alloy. An example of a grain refiner is a 9.525 mm rod comprising 96% aluminum, 3% titanium (Ti) and 1% boron (B), where virtually all boron is present as finely dispersed TiB₂particles. During casting, the grain refining rod is fed in-line into the molten alloy flowing into the casting pit at a controlled rate. The amount of grain refiner included in the alloy is generally dependent on the type of material utilized for grain refining and the alloy production process. Examples of grain refiners include Ti combined with B (e.g., TiB₂) or carbon (TiC), although other grain refiners, such as Al—Ti master alloys may be utilized. Generally, grain refiners are added in an amount ranging from 0.0003 wt. % to 0.005 wt % to the alloy, depending on the desired as-cast grain size. In addition, Ti may be separately added to the alloy in an amount up to 0.15 wt. % (cumulative), depending on product form, to increase the effectiveness of grain refiner, and typically in the range of 0.01 to 0.03 wt. % Ti. When Ti is included in the alloy, it is generally present in an amount of from 0.01 to 0.10 wt. %. In one embodiment, the aluminum alloy includes a grain refiner, and the grain refiner is at least one of TiB₂and TiC, where the wt. % of Ti in the alloy is from 0.01 to 0.06 wt. %, or from 0.01 to 0.03 wt. %.

The new 5xxx-lithium aluminum alloy products may include impurities of iron, copper, silver, silicon and/or manganese. Iron may be included in the alloy as an impurity in an amount of up to 0.25 wt. %. In one embodiment, the new 5xxx-lithium aluminum alloy products contain not greater than 0.15 wt. % Fe as an impurity. In another embodiment, the new 5xxx-lithium aluminum alloy products contain not greater than 0.12 wt. % Fe as an impurity. In yet another embodiment, the new 5xxx-lithium aluminum alloy products contain not greater than 0.10 wt. % Fe as an impurity. In another embodiment, the new 5xxx-lithium aluminum alloy products contain not greater than 0.08 wt. % Fe as an impurity. In yet another embodiment, the new 5xxx-lithium aluminum alloy products contain not greater than 0.06 wt. % Fe as an impurity. As described above, copper, silver, silicon and/or manganese may be included in the alloy as an impurity, and when any of such elements are in the alloy as an impurity, the new 5xxx-lithium aluminum alloy products may include up to 0.04 wt. % each of any of such elements.

The new 5xxx-lithium aluminum alloy products generally contain low amounts of “other elements” (e.g., casting aids). As used herein, “other elements” means any other element of the periodic table except for aluminum and the above-described magnesium, lithium, zinc, copper, silver, silicon, manganese, titanium, grain structure control elements (i.e., Zr, Sc, Cr, V Hf, and other rare earth elements), and iron, as described above. In one embodiment, a new 5xxx-lithium aluminum alloy product contains not more than 0.10 wt. % each of any other element, with the total combined amount of these other elements not exceeding 0.35 wt. %. In another embodiment, each one of these other elements, individually, does not exceed 0.05 wt. % in a new 5xxx-lithium aluminum alloy product, and the total combined amount of these other elements does not exceed 0.15 wt. % in a 5xxx-lithium aluminum alloy product. In another embodiment, each one of these other elements, individually, does not exceed 0.03 wt. % in a 5xxx-lithium aluminum alloy product, and the total combined amount of these other elements does not exceed 0.10 wt. % in a 5xxx-lithium aluminum alloy product.

For the purposes of this patent application, the below chart identifies the difference between impurities and other elements.

Impurities Other Elements Iron (when the alloy contains Any element of the periodic table 0.25 wt. % Fe or less) except the following: Optionally copper (when the Aluminum alloy contains 0.04 wt. % Magnesium Cu or less) Lithium Optionally silver (when the Zinc alloy contains 0.04 wt. % Copper Ag or less) Silver Optionally silicon (when the Silicon alloy contains 0.04 wt. % Titanium Si or less) Manganese Optionally manganese (when the Zirconium alloy contains 0.04 wt. % Scandium Mn or less) Chromium Vanadium Hafnium Other rare earth elements (i.e., Yttrium, Lanthanum, Cerium, Praseodymium, Neodymium, Promethium, Samarium, Europium, Gadolinium, Terbium, Dysprosium, Holmium, Erbium, Thulium, Ytterbium and Lutetium)

BRIEF DESCRIPTION OF THE DRAWINGS

FIGS. 1a-1d are graphs illustrating mechanical properties of various Example 1 alloys.

FIG. 2a-1 is a graph illustrating the strength-toughness performance of various Example 2 alloys.

FIG. 2a-2 is a graph illustrating the strength-toughness performance of various Example 2 alloys.

DETAILED DESCRIPTION EXAMPLE 1

Various 5xxx-lithium aluminum alloys were cast in book molds to make ingots approximately 3 inches thick. The alloy compositions are provided in Table 1, below.

TABLE 1 Example 1 Alloy Compositions and Density (all values in weight percent) Density Alloy Mg Li Cu Zn Ag (*1000 kg/m3) Alloy 1 5.76 2.26 — — — 2.47 Alloy 2 4.65 1.55 — — — 2.53 Alloy 3 3.83 1.94 — — — 2.52 Alloy 4 4.54 1.87 — — — 2.51 Alloy 5 5.54 1.89 — — — 2.5 Alloy 6 4.63 1.67 — 1.54 — 2.54 Alloy 7 4.71 1.58 — — 0.66 2.54 Alloy 8 4.61 1.64 0.53 1.54 — 2.56

Alloy 1 is based on conventional Russian alloy 01420 (the “1420” alloy). All of Alloys 1-8 contain not greater than 0.04 wt. % Si, not greater than 0.06 wt. % Fe, not greater than 0.04 wt. % Mn, and from 0.10 to 0.12 wt. % Zr, the balance being aluminum and other elements, the other elements not exceeding 0.05 wt. % each, and the combined amount of the other elements not totaling more than 0.15 wt. %.

After casting, all of the alloys were scalped, homogenized (preheated), and then hot rolled to final gauge of about 0.25 inch, after which the alloys were allowed to cool to room temperature. Next, the alloys were solution heat treated and quenched, after which the alloys were stretched about 3%, and then aged at 300° F. for various times, placing the alloys in a T8 temper. The mechanical properties of the aged samples were then tested in accordance with ASTM E8 and B557, the results of which are shown in Table 2, below, and illustrated in FIGS. 1a1-c (all values averages of duplicate test specimens).

TABLE 2 Example 1 Alloys - Longitudinal (L) Strength and Elongation Properties Alloy Aging Time TYS (L) UTS (L) Elongation Number (hours) (ksi) (ksi) (L) (%) Alloy 1 0 34.3 55.05 26 Alloy 1 16 47.55 69.5 14 Alloy 1 24 48.5 69.75 14 Alloy 1 40 49.5 70.75 14 Alloy 2 0 35.1 46.4 26 Alloy 2 16 41.05 56.6 18 Alloy 2 24 41 57.1 18 Alloy 2 40 41.2 57 18 Alloy 3 0 32.95 43.75 25 Alloy 3 16 41 57.75 17 Alloy 3 24 41.4 58.2 15.5 Alloy 3 40 41.9 59.5 14 Alloy 4 0 35.5 49.3 24 Alloy 4 16 43 61.9 16 Alloy 4 24 45 63.5 16 Alloy 4 40 44.7 63.35 15.5 Alloy 5 0 36.7 53.85 26 Alloy 5 16 46.75 66.7 15 Alloy 5 24 47.25 67.35 15.5 Alloy 5 40 47.8 68.6 16 Alloy 6 0 36 48.85 24 Alloy 6 16 49.1 64.75 14.5 Alloy 6 24 49.7 66.3 12 Alloy 6 40 50.3 67.95 13 Alloy 7 0 35.8 45.95 24 Alloy 7 16 45.25 57.55 16 Alloy 7 24 46.45 59.85 16 Alloy 7 40 46.15 60 16 Alloy 8 0 38.85 52.55 24 Alloy 8 16 50.9 65.6 17 Alloy 8 24 54.75 69.95 14 Alloy 8 40 53.15 69.7 14

Next, long transverse (LT) strength T-L plane strain fracture toughness tests were performed on the 24-hour aged alloy samples, the results of which are shown in Table 3, below, and illustrated in FIG. 1d.

TABLE 3 Example 1 Alloys - Long Transverse (LT) Strength and T-L Toughness Properties Tensile Yield T-L plane strain Strength (LT) fracture toughness Alloy (ksi) (ksi✓in.) Alloy 1 48.4 21.6 Alloy 2 41 23.6 Alloy 3 41.4 22.3 Alloy 4 45 22.5 Alloy 5 47.2 24.9 Alloy 6 49.7 31.2 Alloy 7 46.4 21.9 Alloy 8 54.8 26.4

As shown above, and in FIGS. 1a-1d, alloys having zinc and/or copper additions realize improved properties over conventional Russian alloy 1420 (Alloy 1). Indeed, as shown in FIGS. 1a-1c, Alloys 6 and 8, both achieve improved tensile yield strength over Alloy 1 (FIG. 1a), and with comparable ultimate tensile strength (1b) and elongation (1c). As shown in FIG. 1d, Alloys 6 and 8 realize an improved strength-toughness combination over Alloy 1.

EXAMPLE 2

Various 5xxx-lithium aluminum alloys were cast in book molds to make ingots, and then processed to a 0.25 inch (approx.) rolled product in the T8 temper per Example 1, above. The alloy compositions are provided in Table 4, below.

TABLE 4 Example 2 Alloy Compositions and Density Alloy Density Invention Number Mg Li Zn Cu Ag (*1000 kg/m3) Cu + Ag Alloy? 9 4.32 2.02 0.95 0.345 0.23 2.51 0.575 Yes 10 4.33 2.11 1.85 0.355 0.235 2.53 0.59 Yes 11 4.53 2.095 0.97 0.955 0.245 2.53 1.2 No 12 4.405 2.105 1.910 0.935 0.24 2.54 1.175 No 13 4.405 2.17 0.096 0.345 0.65 2.51 0.995 Yes 14 4.365 1.995 1.87 0.355 0.655 2.55 1.01 Yes 15 4.355 1.99 0.975 0.955 0.66 2.55 1.615 No 16 4.375 2.065 1.895 0.895 0.625 2.55 1.52 No 17 4.395 2.025 1.455 0.66 0.44 2.54 1.065 Yes 18 4.285 2.14 2.82 0.635 0.43 2.56 2.325 No 19 4.43 2.115 1.435 1.875 0.45 2.56 1.595 No 20 4.44 2.12 1.49 0.675 0.92 2.55 1.11 No 21* 4.445 1.975 1.44 0.665 0.445 2.54 1.11 Yes 22* 4.395 2.09 1.45 0.665 0.445 2.53 1.065 No

Unless otherwise noted below, all of Alloys 9-22 contain not greater than 0.04 wt. % Si, not greater than 0.06 wt. % Fe, not greater than 0.04 wt. % Mn, not greater than 0.02 wt. % Ti (added as a grain refiner), from 0.10 to 0.13 wt. % Zr, the balance being aluminum and other elements, the other elements not exceeding 0.05 wt. % each, and the combined amount of the other elements not totaling more than 0.15 wt. %.

- Alloy 21 contained 0.24 wt. % Si.
- Alloy 22 contained 0.89 wt. % Si.

The mechanical properties of the aged samples were then tested in accordance with ASTM E8 and B557, the results of which are shown in Tables 5-6, below (values averages of duplicate test specimens), and some of which are illustrated in FIGS. 2a-1 through 2d-2. As shown, the invention alloys (9-10, 13-14, 17 and 21) realize an improved strength-toughness relationship, and contain from 4.32 to 4.45 wt. % Mg, from 1.975 to 2.17 wt. % Li, and from 0.95 to 1.87 wt. % Zn. The invention alloys also all contain an amount of Cu+Ag that does not exceed 1.11 wt. %. The invention alloys also contain up to 0.24 wt. % Si. The non-invention alloys (11-12, 15-16, 18, 20 and 22) either contain too much Cu+Ag (alloys 11-12, 15-16, 18, 20) or contain too much silicon (alloy 22). These best performing alloys contain about 0.35 wt. % Cu and with from about 0.2 to about 0.7 wt. % Ag.

TABLE 5 Example 2 Alloys - Longitudinal (L) Strength and Elongation Properties Tensile Ultimate Aging Aging Yield Tensile Alloy Time Temp. Strength Strength Elonga- Number (hours) (F.) (ksi) (ksi) tion (%) Alloy 9 0 300 27.2 56 23 Alloy 9 0 300 26.9 52.4 25 Alloy 9 10 300 44.9 68.1 15 Alloy 9 10 300 44.6 67.3 14 Alloy 9 16 300 46.2 68.2 14 Alloy 9 16 300 46.3 69.4 14 Alloy 9 24 300 48.8 72.9 12 Alloy 9 24 300 47.7 70.9 12 Alloy 9 40 300 46 67.7 14 Alloy 9 40 300 47.8 69.9 12 Alloy 10 0 300 29.6 54.8 24 Alloy 10 0 300 28.5 56 24 Alloy 10 10 300 48.9 69.8 11 Alloy 10 10 300 49 67.9 10 Alloy 10 16 300 50.6 72.6 11 Alloy 10 16 300 49.5 69.7 10 Alloy 10 24 300 51.8 71.7 9 Alloy 10 24 300 51.4 72.3 10 Alloy 10 40 300 53.8 71.4 10 Alloy 10 40 300 52.5 70.6 8 Alloy 11 0 300 28.6 50.1 20 Alloy 11 0 300 28.8 50.5 20 Alloy 11 10 300 45.9 64.4 10 Alloy 11 10 300 46.8 64 10 Alloy 11 16 300 46.9 65.1 10 Alloy 11 16 300 47.3 65.1 10 Alloy 11 24 300 49.2 65.6 9 Alloy 11 24 300 47.8 65.4 9 Alloy 11 40 300 48.4 66 8 Alloy 11 40 300 49.5 66.7 8 Alloy 12 0 300 27.9 49.8 16 Alloy 12 0 300 27.9 50.1 17 Alloy 12 10 300 45.2 63.3 10 Alloy 12 10 300 45.8 62.3 9 Alloy 12 16 300 47.6 63.4 9 Alloy 12 16 300 46.2 62.9 8 Alloy 12 24 300 46.8 64.1 8 Alloy 12 24 300 47.1 63.5 7 Alloy 12 40 300 48.1 63 7 Alloy 12 40 300 47.6 63.8 7 Alloy 13 0 300 27.7 54.7 21 Alloy 13 0 300 28.4 53.4 23 Alloy 13 10 300 46.7 67.3 13 Alloy 13 10 300 46.1 67.9 11 Alloy 13 16 300 46.5 68.5 11 Alloy 13 16 300 45.2 68.9 11 Alloy 13 24 300 47.9 68.4 9 Alloy 13 24 300 48 71.3 10 Alloy 13 40 300 49.9 70.7 10 Alloy 13 40 300 49.4 70.4 10 Alloy 14 0 300 29.5 51.9 20 Alloy 14 0 300 29.5 52.9 20 Alloy 14 10 300 48.1 65.8 14 Alloy 14 10 300 49 65.6 11 Alloy 14 16 300 50.8 66.8 9 Alloy 14 16 300 49.3 66.9 12 Alloy 14 24 300 51.1 68 9 Alloy 14 24 300 51.2 66.8 9 Alloy 14 40 300 51.7 65.3 7 Alloy 14 40 300 52.7 66.9 7 Alloy 15 0 300 27 47.7 17 Alloy 15 0 300 27.3 47.4 21 Alloy 15 10 300 44 59.7 8 Alloy 15 10 300 45.3 59.7 8 Alloy 15 16 300 45.3 61.8 10 Alloy 15 16 300 46 61.5 9 Alloy 15 24 300 46.8 62.3 8 Alloy 15 24 300 46.5 62.7 10 Alloy 15 40 300 48 62.9 10 Alloy 15 40 300 47.2 62.9 9 Alloy 16 0 300 28.4 48.6 15 Alloy 16 0 300 27.2 47.1 15 Alloy 16 10 300 44.3 59.5 8 Alloy 16 10 300 45 58.4 8 Alloy 16 16 300 45.4 59.2 7 Alloy 16 16 300 45.8 59.7 7 Alloy 16 24 300 47.5 61.5 9 Alloy 16 24 300 46 61.2 7 Alloy 16 40 300 47.4 61.4 8 Alloy 16 40 300 46.9 61 6 Alloy 17 0 300 28.5 48.8 20 Alloy 17 0 300 28 49.9 20 Alloy 17 10 300 46.7 62.9 11 Alloy 17 10 300 45.6 61.9 11 Alloy 17 16 300 46.7 64.6 11 Alloy 17 16 300 46.2 62.9 9 Alloy 17 24 300 47 65.1 9 Alloy 17 24 300 47.5 65.5 10 Alloy 17 40 300 48.3 65.1 10 Alloy 17 40 300 47.7 64 8 Alloy 18 0 300 27.6 48 14 Alloy 18 0 300 26.9 48.5 19 Alloy 18 10 300 45 58.5 7 Alloy 18 10 300 46.1 61 10 Alloy 18 16 300 46.4 59.1 6 Alloy 18 16 300 46.7 60.3 8 Alloy 18 24 300 45.8 61 7 Alloy 18 24 300 47 62 8 Alloy 18 40 300 47.9 60.7 6 Alloy 18 40 300 49.4 62.4 8 Alloy 19 0 300 27 48.6 19 Alloy 19 0 300 26.6 47.8 15 Alloy 19 10 300 45.7 60.3 12 Alloy 19 10 300 44.5 60.1 12 Alloy 19 16 300 45.4 59.7 8 Alloy 19 16 300 45.5 60.2 7 Alloy 19 24 300 46.2 61 7 Alloy 19 24 300 46.4 61.3 7 Alloy 19 40 300 46.7 62.3 8 Alloy 19 40 300 48 62.7 8 Alloy 20 0 300 28.8 47.4 15 Alloy 20 0 300 29.4 47.7 15 Alloy 20 10 300 47.2 60.3 8 Alloy 20 10 300 46.3 58.2 6 Alloy 20 16 300 47.7 60.3 6 Alloy 20 16 300 48.6 60.9 7 Alloy 20 24 300 49.2 60.6 6 Alloy 20 24 300 49.9 60.7 5 Alloy 20 40 300 48.8 61.4 5 Alloy 20 40 300 50 61.7 5 Alloy 21 0 300 28.1 48.5 19 Alloy 21 0 300 27 48 21 Alloy 21 10 300 42.7 60.8 11 Alloy 21 10 300 42.8 60.7 10 Alloy 21 16 300 43.7 61.6 9 Alloy 21 16 300 44.6 61.5 10 Alloy 21 24 300 47.1 63.6 10 Alloy 21 24 300 45.3 61.8 9 Alloy 21 40 300 46 62.9 9 Alloy 21 40 300 45.7 62.8 9 Alloy 22 0 300 28.8 47.7 20 Alloy 22 0 300 28 47 19 Alloy 22 10 300 45.1 60.5 9 Alloy 22 10 300 45.6 60.1 9 Alloy 22 16 300 47.3 60.8 9 Alloy 22 16 300 47.3 60.9 9 Alloy 22 24 300 48.5 62.6 9 Alloy 22 24 300 48.3 61.3 7 Alloy 22 40 300 49.2 62 7 Alloy 22 40 300 48.4 62.4 7

TABLE 6 Example 2 Alloys - Long Transverse (LT) Strength and T-L Toughness Properties (aged at 300° F. for 24 hours, except for Alloy 9, which was aged at 300° F. for 10 hours) Tensile Ultimate T-L plane Yield Tensile Elonga- strain fracture Strength Strength tion toughness Alloy (LT) (ksi) (LT) (ksi) (LT) (%) (ksi✓in.) Alloy 9 45.85 69.25 9 35.7 Alloy 10 52.75 72.2 8 31.9 Alloy 11 49.2 65.85 7 26.2 Alloy 12 47.7 64.55 9 22.9 Alloy 13 49.3 71.1 10.5 32.6 Alloy 14 51.6 67.8 8.5 28.1 Alloy 15 49 60.25 5.5 25 Alloy 16 48.65 62.85 8 24.7 Alloy 17 49.7 66.35 9 26.4 Alloy 18 49.35 61.35 5 20.8 Alloy 19 51.15 62.6 8.5 21.5 Alloy 20 47.9 61.3 6.5 24.3 Alloy 21 45.9 61.25 7 31.1 Alloy 22 49.95 62.3 7 22.5

While various embodiments of the new technology described herein have been described in detail, it is apparent that modifications and adaptations of those embodiments will occur to those skilled in the art. However, it is to be expressly understood that such modifications and adaptations are within the spirit and scope of the presently disclosed technology.

Claims

1. An aluminum alloy consisting of:

from 3.75 to 5.0 wt. % magnesium (Mg);

from 1.6 to 2.3 wt. % lithium (Li);

from 0.50 to 2.5 wt. % zinc (Zn);

0.05 to 0.50 wt. % of a grain structure control element selected from the group consisting of zirconium (Zr), scandium (Sc), chromium (Cr), vanadium (V), hafnium (Hf), other rare earth elements, and combinations thereof;

up to 1.00 wt. % copper (Cu);

up to 1.00 wt. % silver (Ag); wherein Cu+Ag≧1.15 wt. %; wherein, when the aluminum alloy contains not greater than 0.04 wt. % Cu and not greater than 0.04 wt. % Ag, the aluminum alloy contains at least 0.75 wt. % zinc;

up to 0.5 wt. % silicon (Si);

up to 1.0 wt. % manganese (Mn);

up to 0.15 wt. % titanium (Ti); and

the balance being aluminum, other elements and impurities, wherein the aluminum alloy contains not greater than 0.10 wt. % of any one of the other elements, and wherein the aluminum alloy contains not greater than 0.35 wt. % total of the other elements.

2. The aluminum alloy of claim 1, wherein the aluminum alloy contains at least 40 wt. % Mg.

3.-5. (canceled)

6. The aluminum alloy of claim 2, wherein the aluminum alloy contains not greater than 4.9 wt. % Mg.

7.-9. (canceled)

10. The aluminum alloy of claim 1, wherein the aluminum alloy contains at least 1.65 wt. % Li.

11.-12. (canceled)

13. The aluminum alloy claim 10, wherein the aluminum alloy contains not greater than 2.20 wt. % Li.

14. (canceled)

15. The aluminum alloy of claim 1, wherein the aluminum alloy contains at least 0.60 wt. % Zn.

16.-19. (canceled)

20. The aluminum alloy of claim 15, wherein the aluminum alloy contains not greater than 2.25 wt. % Zn.

21. (canceled)

22. The aluminum alloy of claim 1, wherein the aluminum alloy contains at least 0.05 wt % Cu.

23.-25. (canceled)

26. The aluminum alloy of claim 22, wherein the aluminum alloy contains not greater than 0.90 wt. % Cu.

27.-29. (canceled)

30. The aluminum alloy of claim 1, wherein the aluminum alloy contains at least 0.05 wt. % Ag.

31.-33. (canceled)

34. The aluminum alloy of claim 30, wherein the aluminum alloy contains not greater than 0.90 wt. % Ag.

35.-37. (canceled)

38. The aluminum alloy of claim 1, wherein the aluminum alloy contains not greater than 1.10 wt. % Cu+Ag.

39.-40. (canceled)

41. The aluminum alloy of claim 1, wherein the aluminum alloy contains at least 0.05 wt. % of at least one of Cu and Ag, and wherein the new aluminum alloy contains at least 0.15 wt. % Cu+Ag.

42.-46. (canceled)

47. The aluminum alloy of claim 1, wherein the aluminum alloy contains not greater than 0.35 wt. % Si.

48. (canceled)

49. The aluminum alloy of claim 47, wherein the aluminum alloy contains at least 0.05 wt. % Si.

50. The aluminum alloy of claim 1, wherein the aluminum alloy contains not greater than 0.75 wt. % Mn.

51.-52. (canceled)

53. The aluminum alloy of claim 50, wherein the aluminum alloy contains at least 0.20 wt. % Mn.

54.-55. (canceled)

56. The aluminum alloy of claim 1, wherein the grain structure control element comprises zirconium, and wherein the aluminum alloy contains from 0.05 wt. % to 0.20 wt. % Zr.

57.-59. (canceled)

60. The aluminum alloy of claim 56, wherein the aluminum alloy contains from 0.01 to 0.10 wt. % Ti.

61.-62. (canceled)

63. The aluminum alloy of claim 60, wherein the impurities comprise iron (Fe), and wherein the aluminum alloy contains not greater than 0.25 wt. % Fe.

64.-71. (canceled)