Compared with other kinds of superalloys, high temperature niobium alloy has the advantages of low density, high temperature (600~1600 ℃) specific strength, good cold and hot forming performance, good welding performance, etc., can be processed to form thin-wall and complex shape parts. Thrust chamber body extensions for attitude control/orbit control engines for rocket engines, satellites, spacecraft and missiles are one of the important candidate materials for aerospace structural components.
In aerospace, the most used is C-103 and Nb521 alloys, at present, orbit control/attitude control engine refractory metal material thrust chamber has formed a "two generation" series of products. Among them, the "first generation" is niobium hafnium alloy (i.e. C-103) and the "815" coating system, and the "second generation" is niobium tungsten alloy (i.e. Nb521) and the "056" coating system. C-103(Nb-10Hf-1Ti) alloy is a kind of low strength niobium alloy with good high temperature strength, excellent formability and weldability, which is widely used in rocket propulsion and other fields. The alloy is manufactured in China and applied to the two-component liquid rocket engine, and the niobium silicide high temperature anti-oxidation protection coating is used, and the working temperature can reach 1200~1300 ℃. Good formability and stable reliability make C-103 niobium alloy with excellent cost performance, and further promote its application in the field of aerospace.
Due to the limitation of the use temperature and high temperature mechanical properties, C-103 alloy and niobium silicide anti-oxidation coating have been difficult to meet the growing needs of spacecraft. Therefore, Nb521(Nb-5W-2Mo-1Zr) niobium alloy has been developed in our country on the basis of 5Β μ-niobium alloy from the Soviet Union. The alloy uses a high temperature anti-oxidation coating of molybdenum silicide, which increases the operating temperature to about 1550 ° C, significantly reducing the flow rate used to cool the combustion chamber propellant, and thus effectively increasing the specific impact of the engine.
Nb521 niobium alloy is a medium strength plastic niobium alloy by adding W, Mo, Zr alloying elements and a small amount of C elements to the niobium matrix, which further improves the mechanical properties of niobium alloy at room temperature and high temperature by means of solid solution strengthening and precipitation strengthening.
