The evolution of technology for structural materials over the last 50 years

Structural materials technology has played a key role in human history, especially in the last 50 years. For instance, the tools and techniques developed during the Manhattan Project also presaged an era of nuclear weapons buildup and proliferation. In general, the United States government provided generous funding fo defense-related research and technology during the Cold War, leading to major advances in gas turbine engines and aerospace applications, in the latter case including both lightweight materials and extremely high temperature materials. From the late 1950s through the 1980s, the US invested substantial amounts of research and development resources in understanding the behavior of the so-called refractory metals, especially niobium, molybdenum, tantalum and tungsten. In 1980, the understanding of brittle fracture in molybdenum revealed the role of carbon and oxygen in molybdenum fracture stress. This observation led to new processing techniques to solve the brittleness problem. It paved the way for the development of specialty steels, refractory metals, nickel alloys, titanium alloys, aluminum alloys and composites. For nickel-based alloys, the major application area has been jet engines. Over the last 50 years, the operating temperatures of nickel, iron and cobalt-based superalloys have been driven to extremes through ingenious alloy development, microstructural control through directional solidification and single-crystal techniques, innovative processing techniques and engineering design.