Niobium alloy is a very attractive high temperature material, which has good high temperature strength and good low temperature plasticity. In addition, niobium also has a small thermal neutron absorption cross section, resistance to liquid metal corrosion and good superconductivity (such as NbSn intermetallic compounds, palladium alloy and niobium-titanium alloy) and a series of excellent properties, so that niobium alloy is considered to be one of the most promising high temperature materials.
An alloy composed mainly of niobium microalloying elements is added to the iron base. Niobium is a refractory metal with a melting point of 2467℃ and a high strength in the temperature range of 1093 ~ 1427℃. Compared with tungsten alloy and molybdenum alloy, niobium alloy has good plasticity, excellent processing and welding properties, so it can be made into thin sheets and complex parts, which can be used as thermal protection and structural materials in the aerospace and aviation industry.
Alloying is the most important measure to improve the properties of niobium metal. Adding alloying elements to niobium can obtain special properties of the material, such as increasing strength, improving oxidation resistance, improving plasticity and process properties. There are two types of elements that can affect the properties of niobium, one is the metal element, the other is the oxygen, hydrogen, nitrogen, carbon carbon and other resting elements. Metallic elements are mainly M in the periodic table. Family elements Cr, Mo, W, V. Group elements V and Ta, Group N elements T, Zr, Hf, Al, Si, Sn, etc. They can be added by one or more metals to form two-element or multi-element alloys, and their strengthening mechanism is achieved by solid solution strengthening, precipitation strengthening and work hardening. Intermittent elements are the strongest fortifier of niobium at room temperature, and they can have a positive effect on the strength of niobium only when there are elements (mainly Ti, Zr, Hf) that are easy to form oxides, nitides, and carbides.
Niobium alloy still has good plasticity at low temperature (-196℃). Compared with molybdenum and tungsten, niobium has more types of alloying elements and a higher amount of addition. There are more than ten kinds of niobium alloys produced on an industrial scale. As a structural material, niobium alloys are mainly divided into three categories: high-strength alloys (such as Nb-30W-1Zr, Nb-17W-4Hf-0.1C, Nb-20Ta-15W-5Mo-1.5Zr-0.1C), medium-strength alloys and low-strength high-plastic alloys.
