Thermomechanical processing and properties of niobium alloys

Of all the refractory metals, which have melting points above 2000°C, niobium alloys are the most fabricable and lowest density. Niobium alloys are utilized in applications ranging from communication satellites to human body imaging equipment, yet most scientists and engineers have only limited experience with these materials. Over 95% of all niobium is used as alloy additions in steel and nickel alloys. Only 1-2% of niobium is used in the form of niobium-base alloys or pure niobium metal. Of this small percentage, superconducting niobium-titanium alloy accounts for over one-half of all niobium alloys produced. The remaining usage of niobium is for high temperature niobium alloys and corrosion applications. All of the high-temperature niobium alloys in use today were developed in the 1960s (1-3) for nuclear and aerospace applications. Compared to other refractory metals and the hundreds of refractory alloys investigated in the 1960s - 1970s, commercial niobium alloys are relatively low-strength but they are extremely ductile and can be fabricated into very complex shapes. Even though niobium alloys have useful strength hundreds of degrees above nickel-base super alloys, their use has been limited by oxidation and long-term creep behavior. This paper presents a brief view of how niobium alloys are manufactured today and a summary of their thermomechanical properties. (AU)