Compared with other types of superalloys, high-temperature niobium alloys have the advantages of low density, high specific strength at high temperatures (600~1600 ℃), excellent cold and hot formability, and good weldability. They can be processed into thin-walled and complex-shaped parts. It is one of the important candidate materials for aerospace structural parts, which is used to manufacture components such as the thrust chamber body extension section of attitude control/orbit control engines for rocket engines, satellites, spacecraft and missiles. In the aerospace field, the most widely used alloys in China are C-103 and Nb521. Currently, the refractory metal material thrust chambers for orbit control/attitude control engines have formed a "two-generation" series of products.
The high-temperature mechanical properties of Nb521 are far superior to those of C-103 alloy. At 1600 ℃, its strength is 3 to 4 times that of C-103 alloy and it has been successfully applied to various track control/attitude control engine models. C-103(Nb-10Hf-1Ti) alloy is a low-strength niobium alloy that combines good high-temperature strength, excellent formability and weldability. It is widely used in rocket thrusters and other fields and is a niobium alloy with extremely wide applications. China has replicated this alloy and applied it to two-component liquid rocket engines, using a high-temperature anti-oxidation protective coating of niobium silicide. The working temperature can reach 1200 to 1300 degrees Celsius.
This alloy achieves solid solution strengthening by adding alloying elements such as Hf, Ti and Zr. Among them, the strengthening effect of Zr is relatively significant, while Hf and trace amounts of W mainly improve high-temperature performance. The excellent formability and stable reliability of C-103 niobium alloy make it have an outstanding cost performance and further promote its application in the aerospace field.
Nb521 niobium alloy has excellent room-temperature formability. Generally, uniform transition nozzle extension sections can be prepared by sheet spinning. However, most nozzles are obtained by machining bars, which is difficult to machine and has a relatively low material utilization rate. Therefore, studying the near-net forming and additive manufacturing of Nb521 niobium alloy is an effective method to improve the material utilization rate of this alloy.
