NEW ALUMINUM ALLOYS HAVING BISMUTH AND/OR TIN

Abstract

New aluminum alloys having an improved combination of properties are disclosed. In one approach, anew aluminum alloys may include from 0.50 to 3.0 wt. % of X, wherein X comprises (wt. % Bi+wt. % Sn), from 0.50 to 4.0 wt. % Si, from 0.30 to 2.5 wt. % Mg, up to 1.5 wt. % Cu, up to 2.0 wt. % Zn, from 0.05 to 1.5 wt. % Mn, up to 0.70 wt. % Fe, up to 0.35 wt. % of Cr, up to 0.25 wt. % each of Zr and V, and up to 0.15 wt. % Ti, the balance being aluminum, incidental elements and impurities. The new aluminum alloys may comprise at least 0.20 wt. % excess silicon.

Claims

1. An aluminum alloy comprising: from 0.50 to 3.0 wt. % of X, wherein X comprises (wt. % Bi+wt. % Sn); from 0.50 to 4.0 wt. % Si; from 0.30 to 2.5 wt. % Mg; wherein the aluminum alloy comprises at least 0.20 wt. % excess silicon; from 0.25 to 1.5 wt. % Cu; up to 2.0 wt. % Zn; from 0.05 to 1.5 wt. % Mn; up to 0.70 wt. % Fe; up to 0.35 wt. % of Cr; up to 0.25 wt. % each of Zr and V; up to 0.15 wt. % Ti; the balance being aluminum, optional incidental elements and impurities; wherein the aluminum alloy comprises at least 1.75 mol. % of Y, wherein Y is (mol. % Q-phase+mol. % Al.sub.2Cu+mol. % Mg.sub.2Si) as calculated using PANDAT and a temperature of 340° F.

2. The aluminum alloy of claim 1, comprising not greater than 0.4 wt. % Sn.

3. The aluminum alloy of claim 1, comprising not greater than 0.01 wt. % Sn.

4. The aluminum alloy of claim 3, comprising from 0.4 to 1.2 wt. % Bi.

5. The aluminum alloy of claim 1, comprising at least 0.30 wt. % excess silicon, wherein excess silicon is calculated from the formula ((wt. % Si)−((wt. % Fe)*0.333))−((wt. % Mg)/1.73).

6. The aluminum alloy of claim 5, comprising at least 0.70 wt. % Si.

7. The aluminum alloy of claim 6, comprising at least 0.40 wt. % Mg.

8. The aluminum alloy of claim 7, comprising at least 0.35 wt. % Cu.

9. The aluminum alloy of claim 8, comprising from 0.20 to 1.0 wt. % Zn

10. The aluminum alloy of claim 9, comprising from 0.10 to 0.5 wt. % Fe.

11. The aluminum alloy of claim 10, comprising from 0.10 to 0.60 wt. % Mn

12. The aluminum alloy of claim 11, comprising from 0.02 to 0.12 wt. % Ti.

13. The aluminum alloy of claim 12, wherein strontium is included in the aluminum alloy as an impurity.

14. The aluminum alloy of claim 1, wherein X is selected from the group consisting of Bi, Sn and mixtures thereof, and wherein indium is included in the aluminum alloy as an impurity, and wherein the aluminum alloy comprises less than 0.04 wt. % In.

15. An aluminum alloy comprising: from 0.65 to 1.15 wt. % of X, wherein X is selected from the group consisting of Bi, Sn, In, and combinations thereof; from 0.95 to 1.3 wt. % Si; from 0.45 to 0.70 wt. % Mg; wherein the aluminum alloy comprises at least 0.30 wt. % excess silicon, wherein excess silicon is calculated from the formula ((wt. % Si)−((wt. % Fe)*0.333))−((wt. % Mg)/1.73); from 1.0 to 1.4 wt. % Cu; up to 1.0 wt. % Zn; up to 1.5 wt. % Mn; up to 0.70 wt. % Fe; up to 0.35 wt. % of Cr; up to 0.25 wt. % each of Zr and V; up to 0.15 wt. % Ti; the balance being aluminum, optional incidental elements and impurities; wherein the aluminum alloy comprises at least 2.0 mol. % of Y, wherein Y is (mol. % Q-phase+mol. % Al.sub.2Cu+mol. % Mg.sub.2Si) as calculated using PANDAT and a temperature of 340° F.

16. An aluminum alloy comprising: from 0.5 to 1.4 wt. % of X, wherein X is selected from the group consisting of Bi, Sn, In, and combinations thereof; from 2.2 to 3.5 wt. % Si; from 1.1 to 2.5 wt. % Mg; wherein the aluminum alloy comprises at least 0.50 wt. % excess silicon, wherein excess silicon is calculated from the formula ((wt. % Si)−((wt. % Fe)*0.333))−((wt. % Mg)/1.73); up to 1.5 wt. % Cu; up to 2.0 wt. % Zn; up to 1.5 wt. % Mn; up to 0.70 wt. % Fe; up to 0.35 wt. % of Cr; up to 0.25 wt. % each of Zr and V; up to 0.15 wt. % Ti; the balance being aluminum, optional incidental elements and impurities.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

[0060] FIG. 1 is a graph illustrating the excess silicon content or excess magnesium content of the Example 1 alloys.

[0061] FIG. 2 is a graph illustrating machinability results for Example 2 alloys in the T8 temper.

[0062] FIG. 3 is a graph illustrating machinability results for Example 2 alloys in the T9 temper.

[0063] FIG. 4 is a graph illustrating wear resistance results for Example 2 alloys in the bare (unanodized) condition.

[0064] FIG. 5 is a graph illustrating wear resistance results for Example 2 alloys in the anodized condition.

[0065] FIG. 6 is a schematic view illustrating “Feed/Rev” per Example 2.

DETAILED DESCRIPTION

Example 1—Book Mold Study

[0066] Eleven book mold ingots were produced, the compositions of which are provided in Table 1, below (all values in weight percent).

TABLE-US-00001 TABLE 1 Example 1 Alloy Compositions* Alloy Si Fe Cu Mn Mg Cr Zn Ti Sn Bi 1 0.77 0.44 0.45 0.56 0.74 0.07 — 0.06 — 0.98 2 0.72 0.48 0.32 0.13 0.89 0.13 — 0.03 0.77 0.59 3 0.56 0.39 0.61 — 1.00 0.02 — 0.07 1.01 — 4 0.72 0.49 0.33 — 0.87 0.06 — 0.03 0.83 0.56 5 0.87 0.53 0.44 0.08 0.98 0.24 0.13 0.05 — 0.96 6 0.92 0.62 0.46 0.15 0.98 0.27 — 0.04 — 1.04 7 1.12 0.20 1.18 0.45 0.60 0.11 — 0.05 — 1.00 8 1.14 0.26 1.19 0.54 0.57 0.10 — 0.05 0.37 0.40 9 0.95 0.44 0.82 0.11 0.90 0.25 0.74 0.08 0.60 0.61 10 0.62 0.51 0.75 — 1.02 0.09 — 0.05 — 1.12 11 2.91 0.32 0.42 0.16 1.38 0.12 — 0.10 — 1.00 *All alloys contained the listed elements, the balance being aluminum and other impurities, where the other impurities did not exceed more than 0.05 wt. % each, and not more than 0.15 wt. % total of the other impurities.
Alloy 1 is a conventional 6026 aluminum alloy made without lead called “6026LF.” Alloy 2 is a conventional 6262A aluminum alloy. Alloy 3 is a conventional 6020 aluminum alloy. Alloys 4-11 are new experimental alloys of which alloys 7-9 and 11 are the invention alloys.

[0067] The alloys were cast as about 3-inch (ST)×5-inch (LT)×14-inch (L) ingots that were scalped to about 2.5 inches thick and then homogenized. The ingots were then hot rolled to about 0.25-inch gauge plates, corresponding to an approximate 87% reduction. The plates were then solution heat treated and then cold water quenched. The plates were then cut into pieces, which pieces were processed to one of a T6, T8 or T9 temper, as per below:

[0068] T6: artificially age at 355° F. (° C.) for 8 hours; [0069] T8: cold roll to a final gauge of 0.194 inch (about a 22% reduction) and then artificially age at 355° F. (° C.) for 8 hours; [0070] T9: artificially age at 355° F. (° C.) for 8 hours and then cold roll to a final gauge of 0.194 inch (about a 22% reduction).
The mechanical properties of the pieces were then tested in accordance with ASTM E8 and B557, the results of which are shown in Tables 2-4, below. All tests results are relative to the longitudinal (L) direction.

TABLE-US-00002 TABLE 2 Mechanical Properties of Alloys - T6 temper UTS TYS Elong. Alloy Temper (kis) (ksi) (%) 1 (6026LF) T6 48 43.4 13.7 2 (6262A) T6 49 44.2 13.6 3 (6020) T6 51.2 45 14.1 4 T6 51.5 48 12 5 T6 53 50.1 13.4 6 T6 53.3 50.3 13.5 7 T6 49.6 39.8 18.7 8 T6 52.6 42.4 15.8 9 T6 55 48.3 14.5 10 T6 48.9 44.3 15 11 T6 57.2 50.5 13.3

TABLE-US-00003 TABLE 3 Mechanical Properties of Alloys - T8 temper UTS TYS Elong. Alloy Temper (kis) (ksi) (%) 1 (6026LF) T8 50.8 49.2 7.9 2 (6262A) T8 48.5 46.5 9.2 3 (6020) T8 48.8 46 8.6 7 T8 51.4 46.4 11.9 8 T8 52.8 49.1 10.9 9 T8 55.9 54.3 8.4 10 T8 50.3 47.9 11.4 11 T8 56.1 52.9 8.6

TABLE-US-00004 TABLE 4 Mechanical Properties of Alloys - T9 temper UTS TYS Elong. Alloy Temper (kis) (ksi) (%) 1 (6026LF) T9 54.3 52.5 4.6 2 (6262A) T9 56 53.2 4.4 3 (6020) T9 56.5 53.4 5.4 4 T9 60.3 58.4 4.1 5 T9 62.8 61.2 4.9 6 T9 61.5 60.3 4.6 7 T9 57.7 55.6 7.4 8 T9 62.5 60.6 4.8 9 T9 64.5 63.7 3.8 10 T9 58.2 57.4 4.8 11 T9 66.6 64.1 4.7

[0071] As shown, invention alloys 8-9 and 11 realize higher strengths relative to conventional alloys 1-3 and at comparable elongation values. Further, alloy 7 realizes an improved combination of strength and elongation over the conventional alloys. The invention alloys all include high excess silicon levels, which is expected to improve wear resistance. Non-invention alloys 4-6 contained little excess silicon, so their wear resistance may be low. Non-invention alloy 10 had excess magnesium (not silicon), so its wear resistance is expected to be poor. See Table 5, below, and FIG. 1. The high amounts of Cu+Zn also facilitate solid solution strengthening and may also facilitate corrosion resistance. The use of bismuth additions in favor of tin are expected to improve machinability, to improve crack initiation and fracture toughness under aggressive machining conditions.

TABLE-US-00005 TABLE 5 Excess Silicon and Cu + Zn Content (wt. %) Excess (Excess-Si) × Alloy Si Mg Fe* Si** Cu + Zn (Cu + Zn) 1 0.77 0.74 0.44 0.196 0.45 0.0881 2 0.72 0.89 0.48 0.046 0.32 0.0146 3 0.56 1.00 0.39 −0.148 0.61 −0.0902 4 0.72 0.87 0.49 0.054 0.33 0.0178 5 0.87 0.98 0.53 0.127 0.57 0.0724 6 0.92 0.98 0.62 0.147 0.46 0.0677 7 1.12 0.60 0.20 0.707 1.18 0.8338 8 1.14 0.57 0.26 0.724 1.19 0.8615 9 0.95 0.90 0.44 0.283 1.56 0.4419 10 0.62 1.02 0.51 −0.139 0.75 −0.1046 11 2.91 1.38 0.32 2.006 0.42 0.8424 *As noted in U.S. Pat. No. 4,637,842: “It is usual to assume that a percentage of the total Si content equal to ⅓ of the Fe content is lost to the intermetallic compounds.” **Excess silicon is calculated as (Si − (Fe*0.333))) − (Mg/1.73); a negative number means there is excess magnesium instead of silicon.

[0072] PANDAT calculations were also completed on various ones of the above alloys at an aging temperature of 340° F. to determine the amount of Mg.sub.2Sn, Mg.sub.2Si, Q, and Al.sub.2Cu phases in those alloys. PANDAT calculations were also completed on a prior art alloy described in European Patent No. EP0828008. Table 6 shows the results.

TABLE-US-00006 TABLE 6 PANDAT results - Precipitates Phases (wt. %) Alloy Mg.sub.2Sn Mg.sub.2Si Q Al.sub.2Cu Q + Al2Cu + Mg2Si 2 0.53% — 1.39% — 1.39% 3 0.70% — 1.71% 0.28% 1.99% 4 0.57% — 1.27% 0.05% 1.32% 7 — — 1.25% 1.16% 2.41% 8 0.26% — 1.03% 1.23% 2.26% 9 0.42% — 1.62% 0.59% 2.21% 11  — 0.96% 1.88% — 2.84% Prior Art* 0.56% — 1.53% 0.13% 1.66% *The Prior Art alloy is per Table 1 of EP0828008, which shows an alloy having 1.16 wt. % Si, 0.39 wt. % Fe, 0.45 wt. % Cu, 0.32 wt. % Mn, 0.93 wt. % Mg, 0.042 wt. % Ti, 0.81 wt. % Sn, and 0.45 wt. % Bi, the balance being aluminum and impurities, with ≤0.05 wt. % of any one impurity, and with ≤0.15 wt. % of impurities in total.
As shown, invention alloys 7-9 and 11 are predicted to have high amounts of the applicable precipitate phases (Q, Al.sub.2Cu, Mg.sub.2Si) as comparted to the non-invention alloys and the prior art alloy. Moreover, all the non-invention and prior art alloys contained much higher amounts of Mg.sub.2Sn. As the present inventors have recognized, Mg.sub.2Sn may be detrimental to machinability at the applicable machining temperatures and/or machining feed rates. Thus, the invention alloys define novel and inventive aluminum alloys useful in various applications, including, for instance, applications involving extrusion and/or machining.

Example 2—Pilot Scale Testing

[0073] Six pilot scale billets (11-inch or 14.75-inch rounds) were produced, the compositions of which are provided in Table 7, below (all values in weight percent).

TABLE-US-00007 TABLE 7 Example 2 Alloy Compositions* Alloy Si Fe Cu Mn Mg Cr Zn Ti Sn Bi Alloy 1a  0.74 0.46 0.41 0.56 0.77 0.07 0.02 0.07 0.01 0.89 Alloy 2a  0.79 0.47 0.31 0.03 0.95 0.06 0 0.02 0.74 0.49 Alloy 3a  0.54 0.35 0.71 0.03 0.78 0.065 0.03 0.02 1.08 0 Alloy 8a  1.10 0.25 1.2 0.50 0.55 0.10 0 0.05 0.39 0.36 Alloy 9a  0.90 0.40 0.75 0.10 0.90 0.25 0.73 0.10 0.65 0.60 Alloy 11a 2.80 0.30 0.4 0.15 1.10 0.10 0 0.10 0 1.00 *All alloys contained the listed elements, the balance being aluminum and other impurities, where the other impurities did not exceed more than 0.05 wt. % each, and not more than 0.15 wt. % total of the other impurities.
Alloys 1a-3a were cast to correspond to Alloys 1-3 of Example 1, and Alloys 8a-9a and 11a were cast to correspond to Alloys 8-9 and 11 of Example 1, respectively. Alloys 8a-9a, and 11a are invention alloys.

[0074] Also, as in Example 1, Alloy 1a is a conventional 6026 aluminum alloy made without lead called “6026LF,” Alloy 2a is a conventional 6262A aluminum alloy, and Alloy 3a is a conventional 6020 aluminum alloy.

[0075] After casting, the alloys were homogenized, extruded to into rods (0.587 inch or 0.637 inch), solution heat treated or press-quenched, and then processed to a T8 or T9 temper, as provided in Table 8, below. The T8 materials were solution heat treated (“SHT”), cold drawn, and then artificially aged. The T9 materials were solution heat treated (“SHT”) or press quenched (“PQ”), artificially aged and then cold drawn to the final diameter. All alloys were aged at 350° F. for 8 hours as the artificial aging practice.

TABLE-US-00008 TABLE 8 Example 2 Alloy Processing Cold Press- Drawing Quench Re- Extruded or duction Billet Rod Solution of Final Diameter Diameter Heat Area Diameter Alloy (inch) (inch) Treat? (%) (inch) Temper Alloy 11 0.637 PQ 22% 0.562 T9 1a-T9  Alloy 14.75 0.637 PQ 22% 0.562 T9 2a-T9  Alloy 11 0.587 SHT 33% 0.480 T8 3a-T8  Alloy 11 0.637 SHT 22% 0.563 T8 8a-T8  Alloy 11 0.637 SHT 22% 0.563 T8 9a-T8  Alloy 11 0.637 SHT 10% 0.604 T8 11a-T8 Alloy 11 0.637 SHT 22% 0.563 T9 8a-T9  Alloy 11 0.637 SHT 22% 0.563 T9 9a-T9  Alloy 11 0.637 SHT 10% 0.604 T9 11a-T9

[0076] After processing, the mechanical properties of the alloys were tested in accordance with ASTM E8 and B557, the results of which are shown in Table 9, below. All tests results are relative to the longitudinal (L) direction. Strength values are in units of ksi. Elongation values are in units of percent (%). The reported values are averages of at least four specimens. (UTS=ultimate tensile strength; YS=tensile yield strength.)

TABLE-US-00009 TABLE 9 Example 2 Alloy Mechanical Properties T8 Temper T9 Temper Alloy UTS YS Elong. UTS YS Elong. Alloy 1a  N/A 57.2 55.3 9.0 Alloy 2a  N/A 56.8 55.3 6.3 Alloy 3a  47.4 44.6 17.2 N/A Alloy 8a  57.1 54.8 9.7 65.5 63.7 5.7 Alloy 9a  55.1 53.5 9.7 61.4 59.3 6.0 Alloy 11a 51.8 48.2 10 60.8 58.6 5.0

[0077] As in Example 1, the invention alloys 8-9 and 11 realize higher strengths relative to conventional alloys 1-3 and at comparable elongation values. The invention alloys all include high excess silicon levels, which is expected to improve wear resistance. See Table 10, below. The high amounts of Cu+Zn also facilitate solid solution strengthening and may also facilitate corrosion resistance. The use of bismuth additions in favor of tin are expected to improve machinability, to improve crack initiation and fracture toughness under aggressive machining conditions.

TABLE-US-00010 TABLE 10 Excess Silicon and Cu + Zn Content (wt. %) Excess (Excess-Si) × Alloy Si Mg Fe Si Cu + Zn (Cu + Zn) Alloy 1a  0.74 0.77 0.46 0.142 0.43 0.06095 Alloy 2a  0.79 0.95 0.47 0.084 0.31 0.02615 Alloy 3a  0.54 0.78 0.35 −0.027 0.74 −0.02029 Alloy 8a  1.10 0.55 0.25 0.699 1.20 0.83860 Alloy 9a  0.90 0.90 0.40 0.247 1.48 0.36492 Alloy 11a 2.80 1.10 0.30 2.064 0.40 0.82570

[0078] The machinability of the Example 2 alloys was also tested. Specifically, the T8 and T9 temper alloys were machined per the conditions shown in Table 11, below. The results are shown in Tables 12-13, below, and in FIGS. 2-3.

TABLE-US-00011 TABLE 11 Machinability Conditions Machining Surface Velocity Feed/Rev* Depth per Condition No. (feet per minute) (inch) Pass (inch) 1 600 0.01 0.01 2 600 0.01 0.1 3 200 0.01 0.1 4 100 0.01 0.1 5 600 0.005 0.1 6 100 0.01 0.01 *Feed/Rev = cutting tool feeding distance per revolution (see FIG. 6)

TABLE-US-00012 TABLE 12 Machinability Test Results - T8 Temper Machining Mass Number Chips per Alloy Condition No. (grams) of Chips Gram Alloy 3a-T8 1 1.61 138 85.71 Alloy 3a-T8 2 1.65 72 43.64 Alloy 3a-T8 3 2.2 157 71.36 Alloy 3a-T8 4 2.03 56 27.59 Alloy 3a-T8 5 2.17 189 87.10 Alloy 3a-T8 6 1.91 117 61.26 Alloy 8a-T8 1 1.17 84 71.79 Alloy 8a-T8 2 2.03 161 79.31 Alloy 8a-T8 3 1.51 167 110.60 Alloy 8a-T8 4 1.79 179 100.00 Alloy 8a-T8 5 1.65 230 139.39 Alloy 8a-T8 6 1.35 83 61.48 Alloy 9a-T8 1 1.75 192 109.71 Alloy 9a-T8 2 2.2 108 49.09 Alloy 9a-T8 3 1.71 94 54.97 Alloy 9a-T8 4 1.71 111 64.91 Alloy 9a-T8 5 1.54 223 144.81 Alloy 9a-T8 6 1.59 132 83.02 Alloy 11a-T8 1 2.03 61 30.05 Alloy 11a-T8 2 3.06 155 50.65 Alloy 11a-T8 3 2.37 167 70.46 Alloy 11a-T8 4 2.08 142 68.27 Alloy 11a-T8 5 2.3 291 126.52 Alloy 11a-T8 6 1.44 132 91.67

TABLE-US-00013 TABLE 13 Machinability Test Results - T9 Temper Machining Mass Number Chips per Alloy Condition No. (grams) of Chips Gram Alloy 1a-T9 1 1.87 173 92.51 Alloy 1a-T9 2 3.86 178 46.11 Alloy 1a-T9 3 2.67 113 42.32 Alloy 1a-T9 4 3.41 89 26.10 Alloy 1a-T9 5 2.28 181 79.39 Alloy 1a-T9 6 1.98 133 67.17 Alloy 2a-T9 1 1.51 203 134.44 Alloy 2a-T9 2 2.93 132 45.05 Alloy 2a-T9 3 2.29 136 59.39 Alloy 2a-T9 4 3.1 130 41.94 Alloy 2a-T9 5 2.33 282 121.03 Alloy 2a-T9 6 1.76 178 101.14 Alloy 8a-T9 1 1.12 98 87.50 Alloy 8a-T9 2 1.06 124 116.98 Alloy 8a-T9 3 1.01 88 87.13 Alloy 8a-T9 4 1.86 137 73.66 Alloy 8a-T9 5 1.51 244 161.59 Alloy 8a-T9 6 1.63 209 128.22 Alloy 9a-T9 1 1.14 121 106.14 Alloy 9a-T9 2 1.71 161 94.15 Alloy 9a-T9 3 1.6 133 83.13 Alloy 9a-T9 4 2.53 194 76.68 Alloy 9a-T9 5 1.77 275 155.37 Alloy 9a-T9 6 1.08 143 132.41 Alloy 11a-T9 1 1.24 118 95.16 Alloy 11a-T9 2 1.46 119 81.51 Alloy 11a-T9 3 1.95 128 65.64 Alloy 11a-T9 4 2.36 110 46.61 Alloy 11a-T9 5 1.54 209 135.71 Alloy 11a-T9 6 1.72 322 187.21

[0079] As shown, despite being substantially stronger than Alloys 1a-3a, invention alloys 8a-9a, and 11a achieve comparable if not better machinability results at various Machining Conditions. For instance, for Machinability Condition No. 1, Alloy 9 in the T8 temper realized 28% more chips than conventional Alloy 3a in the T8 temper (109.71 versus 85.71 chips per gram yields a ratio of 1.28 or a 28% improvement). For Machinability Condition No. 2, all alloys achieve better machinability, with Alloy 8 in the T8 temper realizing 82% more chips than conventional Alloy 3a in the T8 temper (79.31 versus 50.65 chips per gram yields a ratio of 1.82 or an 82% improvement). Similar results are shown for Machinability Conditions 3-6 for alloys in the T8 temper as well Machinability Conditions 1-6 for alloys in the T9 temper. Thus, the invention alloys may realize an improved combination of strength and machinability.

[0080] Wear testing was also conducted on various ones of the Example 2 alloys as per the “Wear Testing Procedure,” provided below, in both the bare (unanodized) and anodized conditions. The results are provided in Table 14 below and FIGS. 4-5. The average is of three specimens with the standard deviation also provided.

TABLE-US-00014 Average Average (±std.dev) (±std.dev) weight loss weight loss Alloy-Temper (mg) (Bare) (mg) (Anodized) Alloy 3a-T8 19.3 ± 2.1 2.8 ± 0.4 Alloy 8a-T8 22.4 ± 3.0 3.8 ± 0.5 Alloy 9a-T8 24.6 ± 1.2 2.6 ± 0.2 Alloy 11a-T8 18.3 ± 0.3 4.3 ± 0.1 Alloy 1a-T9 20.7 ± 0.9 3.5 ± 0.2 Alloy 2a-T9 22.6 ± 2.1 3.0 ± 0.2 Alloy 8a-T9 24.8 ± 0.5 3.4 ± 0.3 Alloy 9a-T9 22.4 ± 3.5 3.1 ± 0.1

[0081] As shown, the invention alloys (8a-9a, 11a) realize at least comparable wear resistance to the conventional alloys (1a-3a).

[0082] Wear Testing Procedure

[0083] Oscillating linear dry sliding wear tests were performed using a TABER® Linear Abraser Model 5750 to determine the wear index of bare aluminum.sup.1 and a Type III anodized hard coat aluminum.sup.2 (per MIL-A-8625F). A load of 750 grams was applied to the abradant (¼ inch diameter CS-17 WEARASER®). Testing was conducted at 60 cycles per minute using a 4-inch stroke length for 10,000 cycles. Refacing of the abradant was performed for 10 cycles with a 350 gram load on an S14 brand refacing strip before testing and after every 1000 cycles. The sample specimens were 6″ long and approximately 0.5″ wide. Specimens were placed in a desiccator prior to and following testing to establish constant weight in lieu of the conditioning specified in ASTM D 4060. Weight loss was measured after every 10,000 cycles. Three replicates were tested for each condition.

Notes:

[0084] 1. The as-machined bare sample surfaces had an average (±std. dev) roughness (Sa) of 31.8±5.1 On (microinches). [0085] 2. The anodizing process comprises cleaning in Bonderite 4215 at 150° F. for 5 minutes followed by sulfuric acid anodizing at 34° F. with an acid concentration of 188 g/L using the following sequence: 10 A/sq. ft. for 10 minutes, 5 minute ramp to 36 A/sq. ft and hold for 25 minutes. DI (deionized) water rinsing followed both steps and the samples were oven dried at 180° F.

End of Wear Test Procedure.

[0086] While a number of embodiments of the present invention have been described, it is understood that these embodiments are illustrative only, and not restrictive, and that many modifications may become apparent to those of ordinary skill in the art. Further still, unless the context clearly requires otherwise, the various steps may be carried out in any desired order, and any applicable steps may be added and/or eliminated.