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Niobium alloy

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Niobium alloy is a metal material with excellent properties due to its high strength, high corrosion resistance and high thermal stability.

It is widely used in aviation, aerospace, energy, chemical industry and other fields. This article will introduce in detail the properties, mechanical properties, corrosion resistance, production and application, process technology, development prospects and challenges of niobium and gold.

Introduction to niobium alloy
Niobium alloy is an alloy composed of niobium as the main component and a certain amount of titanium, zirconium, hafnium and other elements added. Niobium alloy has excellent strength and corrosion resistance, low density, high melting point, and good processability and welding properties. In high-temperature environments, niobium alloys have excellent creep resistance and fatigue resistance, so they are widely used in aviation, aerospace, energy and other fields.

Physical properties of niobium alloy
The density of niobium alloy is about 8.5g/cm3, the melting point is between 1500-1700℃, and it has good electrical and thermal conductivity. At normal temperature, the resistivity of niobium alloy is about 1.5×10-6Ω·m, and the thermal conductivity is about 43W/(m-K. In addition, niobium alloy also has a low expansion coefficient and good compatibility, and can Combines well with other metals or alloys.

Mechanical properties of niobium alloy
Niobium alloy has excellent mechanical properties. At room temperature, its strength and hardness are high, and its yield strength and tensile strength exceed 10O0MPa. At high temperatures, niobium alloys have better mechanical properties, can withstand operating temperatures up to 600℃, and have good creep resistance and fatigue resistance. These characteristics make niobium alloys widely used in structural materials in aviation, aerospace and other fields.

Corrosion resistance of niobium alloy
Niobium alloy has good corrosion resistance in most environments, especially strong resistance to oxidizing and reducing media. In a high-temperature environment, a dense oxide film will form on the surface of niobium alloy to protect the material. In addition, niobium alloys also have good radiation resistance and can therefore be used in nuclear reactors and radioactive devices.

Production and application of niobium alloy
There are two main production methods for niobium alloy: smelting and powder metallurgy. The smelting method is to heat the raw materials to above the melting point, fully smelt them, pour them into ingots, and then go through cutting, straightening and other processes to make products. The principle of powder metallurgy is to turn raw materials into powder, form them by compression molding or isostatic pressing, and then sinter them to make products.
Niobium alloys are widely used in aviation, aerospace, energy, chemical industry and other fields. In the aviation field, niobium alloys can be used to make aircraft engines and fuselage structural parts; in the aerospace field, niobium alloys can be used to make rocket engines and space structural parts; in the energy field, niobium alloys can be used to make key components such as nuclear reactors and steam generators. ;In the chemical industry, niobium alloys can be used to manufacture materials with high corrosion resistance and high strength.

Process technology of niobium alloy
The processing technology of niobium alloy mainly includes forging, rolling, drawing, bending, cutting, etc. Forging and rolling are mainly used in production
Large or complex structural parts; drawing and bending are used to produce small or special-shaped parts; cutting is used to produce parts of specific shapes and sizes. In addition, heat treatment and cold working are also important links in the processing of niobium alloy. Heat treatment can improve the mechanical properties and corrosion resistance of the material, while cold working can improve the processing accuracy and surface quality of the material.

Development prospects and challenges of niobium alloys
With the continuous advancement of science and technology, niobium alloys have very broad application prospects in the future. With the development of aviation, aerospace, and energy, the demand for materials with high strength, high corrosion resistance, and high temperature stability is increasing, and the excellent properties of niobium alloys meet these needs. In addition, with the continuous development of the fields of green energy and environmental protection, the demand for high efficiency, environmental protection and sustainable development is also increasing, which also brings new opportunities for the development of niobium alloys.

However, the production of niobium alloys is relatively high, which limits their widespread application to a certain extent. Therefore, reducing the production cost of niobium alloy and improving its production efficiency are one of the current challenges. In addition, since different fields have different requirements for material performance, how to meet these specific needs through composition optimization and process adjustment is also one of the issues that need to be solved urgently.

In short, although the production and application of niobium alloys still face some challenges, with the continuous advancement of science and technology and the development of new materials, it is believed that niobium alloys will be widely used in more fields and play an important role in the future.

Niobium Alloy

CHOICES OF NIOBIUM ALLOY

Niobium C103
Niobium Cb752
NbTi Superconducting
Nb521

Niobium Alloy

Niobium Alloy has good high temperature strength and low temperature plasticity, as well as excellent processing and welding performance, but poor oxidation resistance. Generally, the powder metallurgy method of vacuum high temperature sintering, electron beam furnace (EB), vacuum consumable electric arc furnace (VAR) vacuum smelting method is an ideal common method for preparing high-purity niobium alloy ingots.

Physical properties of Niobium Alloy
Grade Cb752 C103
Component Nb-10W-2.5Zr-0.05Mo-0.15Ta-0.1Hf Nb-10Hf-1Ti-0.7Zr-0.1W-0.1Mo-0.05Ta
Density /g.cm-3 8.83 8.86
Melting point /℃ 2349
Linear expansion coefficient /10-6K-1 4.5（1203℃） 4.5（1203℃）
Recrystallization temperature /℃ 1023~1371 1038~1316
Annealing temperature /℃ 982~1093 871
Elongation brittle transition temperature /℃ -196 -196

Main chemical composition of Niobium-based Alloy (mass fraction)

Grade Chemical Composition / % Chemical Composition / 
Nb W Mo Ta V Hf Zr Ti C O N
C103Nb-10Hf-1Ti Balance 　 　 　 　 9~11 ＜0.7 0.7~1.3 ＜100 ＜300 ＜300
Cb752Nb-10W-2.5Zr Balance 9~11 　 　 　 　 2~3 　 10 ＜200 ＜200
Nb521 Balance 4.7~5.5 1.7~2.5 　 　 　 0.7~1.2 　 　 　 　

Choices of Niobium Alloy

Characteristics and applications of Niobium Alloy

Grade Characteristics and applications
Nb1Zr Small thermal neutron capture cross section, strong resistance to liquid metal corrosion, used in atomic energy industry and high pressure sodium lamp industry
C103 High temperature and high strength for the aerospace industry
Cb752 High temperature and high strength for the aerospace industry
Nb-50Ti Good superconductivity, used in superconductor technology; high strength, used in the aerospace industry

Niobium alloy has a high melting point and still has high strength below 1650°C. However, it is easy to generate an oxide film (Nb2O5) without protection at high temperature. Therefore, in addition to improving the oxidation resistance of the base alloy itself, it is also necessary to apply a protective coating to ensure the high temperature performance of the alloy.

Classification of Niobium Alloy

Niobium alloys are generally classified according to service characteristics and strength. Among them, there are 5 types of structural niobium alloys:
1) Low strength niobium alloy
2) Medium strength niobium alloy
3) High strength niobium alloy
4) Low density niobium alloy
5) Interstitial compound strengthened high strength niobium alloy

Niobium alloys classified according to their use characteristics are:
1) Elastic niobium alloy
2) Superconducting niobium alloy
3) Anti-oxidation- niobium alloy
4) Constant expansion niobium alloy

1) Low strength niobium alloy

Using niobium as the base metal, adding IV B group Ti, Zr, Hf and other elements to form a solid solution strengthened alloy, such as Nb-1Zr, Nb-10Hf-1Ti-07Zr, at room temperature, its strength σb=320~420MPa, elongation The rate of δ=20%~40%, and the fusion welding performance is good. Under the temperature of 0.37~0.47 T and vacuum conditions, after 1000h aging treatment, the ductility-brittle transition temperature (DBTT) is still lower than room temperature. Such niobium alloys are used in turbopump nuclear liquid alkali metal delivery pipelines for inter-hole nuclear power plants, as well as for attitude control of spacecraft, satellites, missiles, and thrust chamber body extensions for motor engines.

2) Medium strength niobium alloy

Taking niobium as the base metal, adding no more than 10% of tungsten, molybdenum, tantalum, vanadium, titanium, zirconium, hafnium and other metal elements and a small amount of carbon to form solid solution strengthening and a small amount of ZrO2 (rhombic structure) and (Nb) , Zr) C precipitation strengthening phase combined niobium alloy, such as Cb752 (Nb-10W-2.5Zr), C-129Y (Nb-10W-10Hf-0.1Y) and so on. At room temperature, the strength of these alloys is σb=450~600MPa, and the elongation δ=20%~30%, and there are still quite high strengths between 1000~1400℃. Since these alloys are sensitive to interstitial elements such as hydrogen, oxygen, and nitrogen, their DBTT is relatively high, and the DBTT in the welded state is generally above room temperature. This type of niobium alloy is suitable for the manufacture of riveted and fastened components, such as skins, bolts, nuts, etc.

3) High strength niobium alloy

Taking niobium as the base metal, adding a large amount of tungsten, molybdenum, tantalum, titanium, zirconium and other metal elements and a small amount of carbon and other elements to form a niobium alloy that combines high solid solution strengthening and (Nb, Zr) C precipitation strengthening, such as FS -85 (Nb-28Ta-10W-1Zr) etc. This kind of alloy has quite high tensile strength, creep strength and fatigue strength in the range of 1300~1600℃. This type of niobium alloy is suitable for the manufacture of high temperature components.

4) Low density niobium alloy.

With niobium as the base metal, a large amount of tungsten, molybdenum, tantalum, vanadium, titanium, zirconium, chromium, tin and carbon are added to form a combination of high solid solution strengthening and precipitation strengthening of compounds such as Ti3Al, (Nb, Zr)C. Niobium alloy. The density of these niobium alloys at room temperature is 5.9~6.9g/cm³, which is 70%~80% of the density of niobium; if the surface of the alloy is not coated with anti-oxidation coating, it can be used in the atmospheric environment of 550~800℃ without Oxidized, under the condition of adding anti-oxidation coating, it can be used in the atmospheric environment of 800~1300 ℃, and when the surface coating is damaged, the alloy matrix will not be burned through and destroyed immediately.

5) Interstitial compound strengthened high-strength niobium alloy

Today’s aerospace engineering technology requires a niobium alloy that maintains the plasticity of the existing high-strength niobium alloys, but also has higher strength. The most thermodynamically stable chemical compound is added to the niobium base metal. These niobium alloys have high strength in the range of 1100~1400℃, such as the room temperature strength σb=300MPa and elongation δ=20% of Nb-0.3%ZrO2 (mass fraction) in the recrystallized state at 1300℃/1h; Strength σb=120MPa at 1200℃, elongation δ=36%. This type of niobium alloy has good working plasticity at room temperature and above 800 ℃, as well as alloy ingots.

The stress relief annealing temperatures(keep warm for one hour) for several niobium alloys are as follows
Alloy Nb-10W-1Zr-0.1C Nb-15W-5Mo-1Zr-0.1C Nb-10W-2.5Zr Nb-1-W-28Ta-1Zr Nb-10W-10Hf
Stress relief annealing temperature,℃ 1200 1200 1000 1000 1000
The recrystallization temperatures of several niobium alloys are as follows
Alloy Recrystallization temperature range, ℃ Alloy Recrystallization temperature range, ℃
Nb-5Zr 980-1300 Nb-4V 930-1200
Nb-10Ti-5Zr 970-1150 Nb-5Mo-5V-1Zr 1100-1370
Nb-10W-1Zr-0.1C 1150-1430 Nb-1Zr 1000-1280
Nb-27Ta-10W-0.1Zr 1150-1430 Nb-15W-5Mo -1Zr-0.1C 1540-1760
Nb-10W-2.5Zr 1150-1430 Nb-10W-10Hf 980-1200
Nb-10Hf-1Ti 870-1200 Nb -28W-10Ta -1Zr 1310-1370
Nb-10W-1Hf 980-1200

Niobium alloy tubes, rods and wires are processed by extrusion, forging, rolling and drawing, and are usually supplied in the recrystallized annealed, stress relieved annealed and cold worked conditions.

Applications of Niobium Alloy

Many unique properties of Niobium Alloys determine that it is a multi-purpose functional material. In the electronics, steel, metallurgy, chemistry, cemented carbide, atomic energy and aerospace industries, modern strategic weapons, superconducting technology, scientific research, medical equipment, and even arts and crafts and decoration industries, all involve tantalum metal, alloys and compounds The wide range of applications. Niobium is mostly used in industries and superconducting technologies such as steel, ceramics, and nuclear energy.

Niobium alloy can maintain high strength and good processing performance at high temperature. It can be made into thin plates and parts with complex shapes. Therefore, in some hypersonic aircraft, spacecraft, satellites, missiles and supersonic low-altitude rockets can be used as the preferred thermal protection materials and structural materials.

The superconducting transition temperature of niobium is high, and niobium compounds and alloys can be used to make superconducting materials.

Niobium alloys also have unique applications in chemical industry, medicine and other industries.