Introduction of Nb521 alloy
Nb521 niobium alloy adds W, Mo, Zr alloying elements and a small amount of C element to the niobium matrix. It further improves the room temperature and high temperature mechanical properties of the niobium alloy through a combination of solid solution strengthening and precipitation strengthening. It is a medium-grade niobium alloy. Strength plastic niobium alloy. The alloy can be cast into ingots through vacuum electron beam melting or vacuum electron beam + vacuum consumable melting, and bars and rods of various specifications can be prepared through hot extrusion, forging, cold forging, drawing and rolling. Forgings and plates. W and Mo elements are added to the alloy mainly because of their high melting point and similar atomic radii, which can form a substitutional solid solution to improve the creep resistance and high-temperature strength of the alloy matrix. Zr and C elements are added to the alloy because C easily forms a dispersed and precipitated strengthening phase with Zr and Nb, which plays a role in precipitation strengthening and can further improve the high-temperature strength of the alloy.
Nb521 niobium-tungsten alloy has a density of 8.65-9.0g/cm3, and its matrix chemical composition is Nb. Pure metal Nb has a high solid solubility for W, Mo, Zr and other elements. These elements form a variety of solid solution strengthening phases with Nb, which can significantly improve the mechanical properties of the alloy at room temperature and high temperature; The melting point of W and Mo is high, and the atomic radius is close to that of Nb, which can improve the high-temperature strength and creep properties of Nb alloy; Zr mainly plays the role of forming strengthening phase and improving the strength of Nb matrix.
Nb521 alloy, as a new generation of refractory Nb alloy at high temperature, has excellent mechanical properties at high temperature, high melting point, low density, good plasticity and other advantages, and occupies an important position in the field of aerospace.Nb521 has good plasticity, so it is suitable for forming parts by plastic processing such as spinning. It can be used on the parts of engines.
Chemical composition of Nb521 alloy
| Composition of Nb521 alloy wt% | |||||
|---|---|---|---|---|---|
| W | Mo | Mo Zr | C | N | O |
| 5.14 | 1.87 | 1.33 | 0.0095 | 0.006 | 0.010 |
| Cu | Ti | Fe | Si | Ta | Nb |
| 0.001 | 0.016 | 0.001 | 0.0028 | 0.59 | Balance |
Mechanical properties of Nb521 alloy sheet and bar
| Sample | σb/MPa | σ0.2/MPa | δ5/% | ψ/% | E1/GPa | Bending angle/(°) |
|---|---|---|---|---|---|---|
| Nb521 Rod | 440 | 328 | 31 | 77 | 124 | - |
| Nb521 Sheet | 470 | 340 | 36 | - | - | 180 |
Application of Nb521 alloy to liquid rocket engine
Spinning forming of nozzle extension section for engine fuselage
Through the spinning test, the niobium-tungsten alloy has good forming properties at room temperature, and the limit thinning rate of the material should be about 70%.
Nb521 Niobium Tungsten Alloy fuselage
The engine fuselage developed by NB521 niobium alloy has been tested for several hours after being sprayed with high-temperature oxidizing coating on the surface. It can be judged that the high-temperature part of the engine thrust chamber body should operate at about 1550℃. It can be seen that NB521 has excellent high temperature performance and can fully meet the requirements of high temperature materials for the engine fuselage.
Feature
- Nb521 contains many kinds of carbide reinforcing phase, the aggregation and length of reinforcing phase reduce the high temperature strength of the material.
- Nb521 has excellent room temperature plastic deformation capacity and can be formed at room temperature for more complex workpiece.
- The Nb521 has good mechanical properties at room temperature and can meet the requirements of engine use in 1550℃.
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