Aluminium–zinc alloys explained

Aluminium brass is a technically rather uncommon term for high-strength and partly seawater-resistant copper-zinc cast and wrought alloys with 55–66% copper, up to 7% aluminium, up to 4.5% iron, and 5% manganese. Aluminium bronze is technically correct as bronze, a zinc-free copper-tin casting alloy with aluminium content.

The term "special brass" is much more common for this, which then also includes alloys that add further characteristic elements to the copper-zinc base. In addition to the already mentioned elements of iron and manganese, lead, nickel and silicon can also be found as alloy components.

Due to their aluminium content, which is susceptible to oxidation at the usual melting temperatures in the range of 900 °C, the alloys require careful melting and melting treatment. Even when potting, attention must be paid to any oxides forming.

7000 series

7000 series are alloyed with zinc, and can be precipitation hardened to the highest strengths of any aluminium alloy. Most 7000 series alloys include magnesium and copper as well.

7000 series aluminium alloy nominal composition (% weight) and applications!Alloy!Al contents!Alloying elements!Uses and refs
700593.3Zn 4.5; Mg 1.4; Mn 0.45; Cr 0.13; Zr 0.14; Ti 0.04Extrusions
701093.3Zn 6.2; Mg 2.35; Cu 1.7; Zr 0.1;Aerospace
702291.1Zn 4.7; Mg 3.1; Mn 0.2; Cu 0.7; Cr 0.2;plate, molds[1] [2]
703485.7Zn 11.0; Mg 2.3; Cu 1.0Ultimate tensile strength 750 MPa[3]
703992.3Zn 4.0; Mg 3.3; Mn 0.2; Cr 0.2Aerospace armour plate
704988.1Zn 7.7; Mg 2.45; Cu 1.6; Cr 0.15Universal, aerospace
705089.0Zn 6.2; Mg 2.3; Cu 2.3; Zr 0.1Universal, aerospace
705587.2Zn 8.0; Mg 2.3; Cu 2.3; Zr 0.1Plate, extrusions, aerospace[4]
706588.5Zn 7.7; Mg 1.6; Cu 2.1; Zr 0.1Plate, aerospace[5]
706887.6Zn 7.8; Mg 2.5; Cu 2.0; Zr 0.12Aerospace, Ultimate tensile strength 710 MPa
707299.0Zn 1.0Sheet, foil
7075 & 717590.0Zn 5.6; Mg 2.5; Cu 1.6; Cr 0.23Universal, aerospace, forgings
707991.4Zn 4.3; Mg 3.3; Cu 0.6; Mn 0.2; Cr 0.15
708589.4Zn 7.5; Mg 1.5; Cu 1.6Thick plate, aerospace[6]
7090Al-Zn-Mg-Cu with Co 1.5%high strength, ductility and resistance to stress corrosion cracking[7]
7091Al-Zn-Mg-Cu with Co 0.4%high strength, ductility and resistance to stress corrosion cracking
709386.7Zn 9.0; Mg 2.5; Cu 1.5; O 0.2; Zr 0.1Aerospace
711693.7Zn 4.5; Mg 1; Cu 0.8Heat-treatable
712993.2Zn 4.5; Mg 1.6; Cu 0.7
715089.05Zn 6.4; Mg 2.35; Cu 2.2; O 0.2; Zr 0.1Aerospace
717888.1Zn 6.8; Mg 2.7; Cu 2.0; Cr 0.26Universal, aerospace
725587.5Zn 8.0; Mg 2.1; Cu 2.3; Zr 0.1Plate, aerospace[8]
747590.3Zn 5.7; Mg 2.3; Si 1.5; Cr 0.22Universal, aerospace

Further reading

Notes and References

  1. General Corrosion Resistance Comparisons of Medium- and High-Strength Aluminum Alloys for DOD Systems Using Laboratory-Based Accelerated Corrosion Methods . Placzankis . Brian E. . September 2009 . U.S. Army Research Laboratory . DTIC ADA516812; ARL-TR-4937 . 11 August 2018 . Internet Archive.
  2. http://www.sahamit.co.th/index.php/en/aluminium-alloy-th/7022-aluminium-alloy Sahamit machinery 7022
  3. Web site: RSP alloys datasheet . 2023-02-25 . 2022-03-10 . https://web.archive.org/web/20220310051057/https://www.rsp-technology.com/site-media/user-uploads/rsp-technology-high-strength.pdf . dead .
  4. Web site: 7055 Alloy -T7751 Plate and -T77511 EXTRUSIONS . 2023-02-25 . 2017-12-22 . https://web.archive.org/web/20171222052246/https://www.arconic.com/mill_products/catalog/pdf/alloy7055-t7751techsheet.pdf . dead .
  5. Web site: Aluminum alloy 7065 . 2023-02-25 . 2017-12-22 . https://web.archive.org/web/20171222052330/https://www.arconic.com/mill_products/catalog/pdf/alloy7065factsheet.pdf . dead .
  6. Web site: Aluminum alloy 7085 High strength, high toughness, corrosion-resistant thick plate . 2023-02-25 . 2017-12-22 . https://web.archive.org/web/20171222051748/https://www.arconic.com/mill_products/catalog/pdf/AAP7085-factsheet.pdf . dead .
  7. Book: Davis, Joseph R . Nickel, cobalt, and their alloys . Handbook Committee, ASM International . 1 May 2000 . 978-0-87170-685-0 . 354 . Cobalt . ASM International . https://books.google.com/books?id=IePhmnbmRWkC&pg=PA354.
  8. Web site: Aluminum alloy 7255-T7751 Very high strength, fatigue-resistant plate . 2023-02-25 . 2017-12-22 . https://web.archive.org/web/20171222052537/https://www.arconic.com/mill_products/catalog/pdf/AAP7255-factsheet.pdf . dead .