Application of modern aluminum alloys to aircraft

Aluminum alloys have been the primary material of choice for structural components of aircraft since about 1930. Although polymer matrix composites are being used extensively in high-performance military aircraft and are being specified for some applications in modern commercial aircraft, aluminum alloys are the overwhelming choice for the fuselage, wing, and supporting structure of commercial airliners and military cargo and transport. Well known performance characteristics, known fabrication costs, design experience, and established manufacturing methods and facilities, are just a few of the reasons for the continued confidence in aluminum alloys that will ensure their use in significant quantities for the rest of this century and likely well into the next one. But most significantly, there have been major advances in aluminum aircraft alloys that continue to keep them in a competitive position. In the early years aluminum alloys were developed by trial and error, but over the past thirty years there have been significant advances in our understanding of the relationships among composition, processing, microstructural characteristics and properties. This knowledge base has led to improvements in properties that are important to aircraft applications. This review covers the performance and property requirements for airframe components in current aircraft and describes aluminum alloys and product forms which meet these requirements. It also discusses the structure/property relationships of aluminum aircraft alloys and describes the background and drivers for the development of modern aluminum alloys to improve performance. Finally, technologies under development for future aircraft are discussed.