In the modern era, aluminum alloys are the integral element that keeps the aerospace industry on the cutting edge. Metallurgists are constantly seeking and developing new aluminum alloys to increase the speed, strength, and safety of aircraft. Strong alloys are used to protect aircraft from the stresses of flight; light alloys are used for heat and cold resistance and insulation.
Aluminum is naturally strong, lightweight and very workable. These powerful natural properties are enhanced by combining it with elements such as zinc, copper, and silicon to create a variety of aluminum alloys; some strong, some more malleable for complex aluminum shapes. Modern aircraft parts are made primarily from these alloys, and not just the frame- everything from the engine to the nuts and bolts are made from aluminum due to its attractive cost to weight ratio. Below, you will find some of the most common aluminum alloys found in aircraft, and what they’re used for.
One of the most common of the aluminum alloys, 2024 is primarily alloyed with copper, which gives it incredible strength and high fatigue resistance. This makes it the ideal alloy when a high strength to weight ratio is needed, making it perfect for wings and fuselages which are the parts of the aircraft that undergo the most tension.
Containing magnesium and silicon, aluminum alloy 6061 is very corrosive resistant and is known for its great weldability. The premiere alloy in aluminum extrusion, 6061 is also used to create fuselages and wings- but is very rarely found in airliners. Mostly, it’s used in small, personal airplanes.
Aluminum alloy 6063 is very similar to alloy 6061. Because of this, it’s the most popular alloy for aluminum extrusion.
Because of its light weight and incredible strength that is comparable to most steels, alloy 7075 is used for the main frame of aircraft structures. No other aluminum alloys can match 7075 in fatigue resistance, and its reliability is constantly being worked upon to create faster, safer and cheaper airplanes, and its great anodization quality gives it a great finish. Due to this alloy’s high copper content, it is hard to weld.