Niobium alloy

• Overview

  Niobium alloy is an important refractory metal material composed of niobium matrix and other elements. Niobium is a refractory metal with a melting point of 2467℃ and a high specific strength in the temperature range of 1093 ~ 1427℃. Compared with tungsten and molybdenum alloys, niobium alloys have good plasticity, excellent machining and welding properties, so that niobium alloys can be made into thin plates and complex parts, and can be used as thermal protection and structural materials in aerospace and aviation industries.

• Properties

  Niobium alloy is a very attractive high temperature material, it has good high temperature strength and low temperature plasticity. The high temperature oxidation resistance of niobium is very poor, and it begins to oxidize rapidly at about 600℃.

  
  

  Niobium alloys generally maintain the low temperature plasticity of pure niobium, and still have good plasticity at low temperature (-196℃). Niobium alloy also has much higher strength and other properties than pure niobium. In addition, niobium has a small thermal neutron absorption cross section, resistance to liquid metal corrosion and good superconductivity (such as Nb3Sn intermetallic compounds and niobium-titanium alloy), so niobium alloy is considered to be one of the most promising high temperature materials.

  
  

  Among tungsten, molybdenum, tantalum,andniobium, etcrefractory metal materials, niobium alloy has the highest specific strength.

• Classification

  Niobium alloy mainly includes niobium hafnium alloy, niobium tungsten alloy, niobium zirconium alloy, niobium titanium alloy, niobium tungsten hafnium alloy, niobium tantalum tungsten alloy and niobium titanium alloy.

  As structural materials, niobium alloys can be divided into three main categories:

  
  

  (1) High strength alloys (such as Nb-30W-1Zr, Nb-17W-4Hf-0.1C, Nb-20Ta-15W-5Mo-1.5Zr-0.1C)

  (2)Medium strength alloy

  (3)Low strength high plasticity alloy

• Strengthening Mechanism

  Alloying is the most important measure to improve the properties of niobium metal. The special properties of niobium can be obtained by adding alloying elements, such as improving strength, oxidation resistance, plasticity and process performance. There are two types of elements that can affect the properties of niobium, one is metal elements, the other is oxygen, hydrogen, nitrogen, carbon and other resting elements. The main metallic elements are Cr, Mo, W, V, V, Ta, N, Ta, Zr, Hf, Al, Si, Sn, etc. They can be added with one or more metals to form two-element or multi-element alloys. The strengthening mechanism depends on solid solution strengthening, precipitation strengthening and work hardening. Batch elements are the strongest fortifier of niobium at room temperature, and they can have positive effects on the strength of niobium only when there are elements (mainly Ti, Zr, Hf) which are easy to form oxides, nitrides and carbides.

  
  

• Application

  Important applications of niobium alloys include

  (1 ) Atomic number accurately supporting sodium vapor lamp (Nb-1Zr)

  (2) As MRI (magnetic resonance imaging), NMR (nuclear magnetic resonance), SMES (superconducting magnetic energy storage) SQVID (superconductor quantum energy device), ion accelerator superconductors (such as Nb-50Ti, Nb2Sn)

  (3) Rocket boosters and spouts in aerospace applications (such as Nb-10Hf-1Ti)

  (4) Structural materials in the nuclear industry (e.g. Nb-40Ta)

  
  

  Other compounds such as Nb3Al, which is gaining interest as A candidate for A-15 superconductor, show higher transition temperatures than Nb-Ti alloys and can withstand higher electronic domains. In addition, because of their high melting point and super strength, these alloys are expected to be used in high-temperature structural materials.