There is an increasingly urgent need for lightweight components in the aerospace industry, with aluminium (Al) alloys being the preferred material for aircraft structural parts since their use in the Junkers F.13 aircraft in the 1920s. Compared to other metals, Al alloys have a lower density, which helps reduce the total weight of the aircraft, improving fuel efficiency and load capacity.
An article on ScienceDirect, backed by the National Natural Science Foundation of China, the Science and Technology Development Program of Jilin Province, and the Natural Science Foundation of Chongqing, details the use of non-ferrous metals in the aviation industry. The strength and hardness of Al alloys can be significantly enhanced through alloying and heat treatment, making them suitable for applications involving high loads and vibrations.
Additionally, aircraft are exposed to various climatic conditions and chemical corrosion in the harsh aerospace environment. Al alloys exhibit excellent corrosion and fatigue resistance, ensuring their long-term service life under these conditions.
Furthermore, Al alloys are easily recyclable, which helps reduce resource consumption and lessens environmental impact, aligning with the principles of sustainable development. Although composites have gained popularity in aerospace recently, high-strength Al alloys remain indispensable.
With this article, we intend to review the advancements and applications of aluminium alloys commonly used in aerospace. The traditional strengthening methods and advanced manufacturing and processing technologies for aluminium play a critical role in developing high-performance aviation Al alloys in the future.
In a recent incident, a TikTok video of a passenger catching what looked like duct tape dangling at the exterior of an aircraft raged among viewers. “We looked out of our window and saw this,” the caption read on the original video, which zooms in on a fin-like structure on the engine. However, an aerospace engineer, Max, helped explain the matter in a video viewed over 10 million times. His handle on TikTok is @airplanefactswithmax, where he explained about such an innovative usage of aluminium in the aerospace industry.
“Speed tape is an aluminium-based tape designed specifically for aviation due to the high speeds and the large temperature differentials that aircraft are subjected to,” he says in his signature informative yet emotionless monotone, brandishing a roll of the stuff for the camera.
Aluminium alloys are created by combining aluminium with various elements, such as copper, zinc, manganese, and magnesium. Steel is an alloy made from iron and carbon, often with additional elements like manganese, nickel, chromium, and molybdenum. Titanium alloys consist of titanium combined with elements such as aluminium and vanadium. Superalloys, also known as high-performance alloys, are typically based on nickel and may include elements like chromium, cobalt, and tungsten. Composite materials are formed by combining two or more different substances to achieve specific performance characteristics.
According to thyssenkrupp, the aerospace industry commonly uses seven aluminium alloys, along with three lesser-known but important ones.
2024 is widely used for its high yield strength and fatigue resistance, particularly in wings and fuselages. Variant 2014, known for strength and toughness, is often used in internal structures due to its corrosion susceptibility and suitability for arc welding.
Alloy 5052 is a non-heat-treatable alloy that is highly ductile, corrosion-resistant, and suitable for various aerospace applications. Whereas 6061 is valued for its machinability and welding ease, it is commonly used in lightweight aircraft components.
On one hand, aluminium alloy 7050, known for high corrosion resistance and strength, especially in military applications, is used in wing skins and fuselages; on the other, 7075, whose strength is comparable to steel strength, features excellent fatigue resistance and was widely used in World War II aircraft. 7068 is the hero of the alloys as it is one of the strongest alloys and is suited for harsh conditions in military aircraft.
Among the lesser-known alloys which are equally crucial for the aerospace industry, 2219 offers maximum strength at high temperatures and was even used in the space shuttle Columbia’s external fuel tank. Aluminium alloy variants 6063 and 7475 are primarily used for aesthetic qualities and intricate extrusions, with high fatigue resistance and are found in fuselage bulkheads of large aircraft. This alloy is exceptionally strong, respectively.
The demand for aluminium in aerospace will most likely spike extensively in the upcoming years, especially with the newly developed aluminium-lithium alloys that are potent to reduce aircraft weight and improve performance.
To know what else the the metal holds not only for the aerospace sector but for the entire transportation, go through the detailed points about demand, growth trajectory and utility covered in our report — ‘Future of Aluminium in Transportation Sector - an industry analysis with forecasts to 2027’.
