Aluminum Lithium Alloys (Al-Li-Cu-X)-New Generation Material for Aerospace Applications

Abstract

Significant advantages in weight reduction and increased strength have place advanced aluminum-lithium alloys at forefront of aerospace materials research. These alloys are being developed to fulfill the ever increasing need for high strength, high properties, light weight and cost effective for aerospace industry. Conventional aluminum alloys has long been in service for aerospace application. The addition of lithium to aluminum improves modulus and decrease density compared to conventional aluminum alloys. Atomic weight of lithium is 7 mass units compared to aluminum 23 mass units, hence there is density reduction of about 3% for each weight percent addition of lithium and about 6% increase in Youngs modulus. In principle weight saving for aerospace structural parts could reach up to 15 %. This paper examines effect of lithium addition on properties, physical metallurgy; various phases developed during processing of these alloys. The addition of Lithium to aluminum form coherent, low density Al3Li (δ׳) precipitates. However the binary alloys have poor mechanical properties which are attributed to strain localization and shearing of soft Al3Li (δ׳) precipitates. This problem has been solved by development of ternary and quaternary alloys containing copper and magnesium. In all aluminum-lithium alloys, small addition of zirconium or scandium is done to improve recrystallization. The new developed aluminum lithium alloys series Al-Li-Cu-X are potential candidate to replace existing conventional alloys in terms of enhanced properties with reduced density.

Influence of tool rotational speed on Microstructure and Mechanical Properties of Al-Li Alloy using Friction Stir Welding

“…7 One such variant of Al-Li alloys is the high Cu and medium Li heat-treated AA2050 alloy developed by Pechiney/ Alcan Global Aerospace in 2004. 8 Now a days, This material is applied in lower and upper wing covers, spars, ribs, window and crown frames, upper stage of crew launch vehicle (Ares I) (developed by NASA), the wing ribs of airbus A350, lower wing reinforcement of the world's largest passenger airliner airbus A 380 9 and other internal structures of aircraft in the place of conventional non-lithium bearing aluminum of 2xxx & 7xxx series 10 and in the cryogenic propellant tank. 11…”

Effect of Al3Zr Dispersoid on Microstructure and Mechanical Properties of Al-Cu-Li Alloy During Composite Spinning-Extrusion Forming

“…With the improvement in the requirements for lightweight structural materials in the aerospace industry, Al-Cu-Li alloys with excellent comprehensive properties such as low density, high elastic modulus, and high specific strength are considered as ideal materials for the manufacture of space launch vehicles with rib-ring cylinders (Rioja et al, 2012;Ahmed and Wu, 2013;Dursun and Soutis, 2014;Yu et al, 2015;El-Aty et al, 2018;Zhang et al, 2018). At present, composite spinning-extrusion (CSE), which combines the advantages of both spinning and extrusion processes, is considered as a new method for the integral formation of ribbed ring cylinders (Domack and Wangner, 2015;Tayon et al, 2019).…”

Effects of Pre-Stretching on Creep Behavior, Mechanical Property and Microstructure in Creep Aging of Al-Cu-Li Alloy

“…As one of the currently popular aeronautic and astronautic structural materials, Al-Cu-Li alloys have received worldwide attention and been developed rapidly in relevant production and application for their valuable combination of properties, such as low weight, high modulus and high specific strength [1,2,3]. As an excellent representative of Al-Cu-Li alloys, AA2195 has replaced the incumbent structural material (AA2219) for the cryogenic fuel tank on the space shuttle, as it provides an effective way of lowering the structural weight.…”