Applications of high performance refractory metal alloys


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Refractory metal alloys are known for their distinctive specifications and general properties. Among them is the refractory niobium-based metal alloy C-103, which has various applications in space exploration and propulsion technologies.

Although elements such as molybdenum, tantalum, tungsten, niobium and rhenium are the most well-known refractory metals, this category can be extended to include up to 16 metallic elements.1,2,3,4

Refractory metals all have certain basic properties in common. These include exceptional corrosion resistance, high thermal conductivity and melting points, as well as the retention of high temperature mechanical strength (hot strength).

Due to the durable and resistant properties of refractory elements, they have been researched for applications in a wide range of fields. These include nuclear power, aerospace applications, drilling, metal cutting, chemical processing and electronics.

To increase these properties, combinations of refractory metals and other components, known as refractory metal alloys, have been developed.

For example, steel is generally formed from a combination of iron and carbon; but steel has greater strength than either element individually. These properties are shared by refractory metal alloys, which are formed by alloying tungsten, niobium, molybdenum, tantalum and / or rhenium with other elements.

Refractory metal alloys are an important industrial resource, as they can be used in a wide range of applications, including corrosion resistant coatings and parts and load-bearing components.

Refractory alloys in the aerospace industry

Building devices capable of flying in Earth’s atmosphere or even space travel requires materials that can withstand the changes in temperature and mechanical load that can occur rapidly over a wide range of measurements.5

Although composites and ceramics with these capabilities have been developed, designers routinely find that these materials are not easily fabricated into the complicated shapes required for aerospace applications.6

Compared to composites and ceramics, refractory metal alloys have proven to offer an alternative approach. Not only are they a bit easier to use, they still provide the high temperature resistance and high load characteristics you want.

Tungsten, tantalum, molybdenum, and niobium have each found applications in the aerospace industry due to their common refractory metal properties, including high melting points and high temperature resistance.6

Niobium has the lowest density of all refractory metals, being close to the density of nickel while exhibiting good thermal conductivity. Niobium is also easier to work with than most other refractory metals.

This is attributed to its weldability, as well as its high ductility at room temperature and its low ductile to brittle transition temperature.

Alloy C-103 is one of the niobium-based refractory metals that researchers have studied in their efforts to create refractory metal alloys with the ideal blend of properties needed in aerospace applications.

C-103 displays an encouraging mix of construction characteristics and high temperature resistance.

C-103: A light alloy, high temperature and high strength

A complex alloy, C-103 is based on niobium, with additions of 1% by weight of titanium, 10% by weight of hafnium and traces of other elements.7 Although it is a highly sought-after material, C-103 is still the subject of much research and is constantly at the center of new applications.

Its exceptional mechanical stability and strength over huge temperature ranges have enabled C-103 to be used in aerospace applications since almost the beginning of the space age.8

Alloy C-103 has long been used in aerospace applications in the 1100-1500 °Temperature range C due to its superior stability and strength. This stability and resistance can be maintained from cryogenic temperatures up to 1482 °C, while at room temperature, its yield strength is 341 MPa. This drops to only 65 MPa at 1200 °vs.6,7

Unlike other refractory metal alloys, refractory ceramics or composites developed for the aerospace industry, metal alloy C-103 is relatively easy to form.

Despite its high melting temperature, C-103 can be processed by conventional thermomechanical and melting processes. This allows the C-103 to be formed into a range of complex shapes and can be TIG welded without any significant loss of machinability or ductility.

These characteristics make the metal alloy C-103 well suited for a variety of aerospace applications, for example, rocket engine nozzles, aircraft gas turbines and high temperature valves, while its formability and High temperature performance allowed the C-103 to be used in jet engine afterburner jackets.

The metal alloy C-103 is now under investigation for applications in next-generation aerospace technologies such as thrust augmentation flaps and heat pipes to dissipate heat from hypersonic nose cones and leading edges. .

Refractory metals and metal alloys such as C-103 are suitable for use in a wide variety of industries and are available as rods, bars and plates from HC Starck Solutions.

Metal alloys including MHC (Mo-1.2Hf-0.1C) and TZM (Mo-0.5Ti-0.1Zr) are available, while custom alloys can be supplied on request.

HC Starck Solutions has decades of alloying experience which means that it can offer its customers a full fabrication service when fabricating complex parts from refractory metal alloys.

Refractory alloys and refractory metals are also offered as spherical and irregular powders with precise and narrow particle size distributions for use in powder metallurgy additive manufacturing applications.

The latest developments in additive manufacturing mean that complex components can be more easily produced in a wide range of refractory metals.

In additive manufacturing, this characteristic also offers economic advantages.

Refractory metals and refractory alloys are expensive materials, but since the components are manufactured using only the precise amount of material required, profitability is ensured as there is less waste from the machining process.

Previously, making refractory metal alloys into useful shapes was an exceptionally difficult process, but now these can be easily formed in additive manufacturing, as traditional thermomechanical processing is no longer required.

The references

  1. Baucio, M. ASM Metals Reference Book, 3rd Edition. (ASM International, 1993).
  2. Snead, LL, Hoelzer, DT, Rieth, M. & Nemith, AAN Refractory alloys: Vanadium, Niobium, Molybdenum, Tungsten. in Structural alloys for nuclear energy applications 585-640 (Elsevier, 2019). doi: 10.1016 / B978-0-12-397046-6.00013-7.
  3. Harvell, MB What are refractory metals.
  4. International Journal of Refractory Metals and Hard Materials.
  5. Zhang, S. & Zhao, D. Aerospace Materials Manual. (CRC Presse, 2012).
  6. Satya Prasad, VV, Baligidad, RG & Gokhale, AA Niobium and other high temperature refractory metals for aerospace applications. in Aerospace materials and materials technologies (eds. Prasad, NE & Wanhill, RJH) 267-288 (Springer Singapore, 2017). doi: 10.1007 / 978-981-10-2134-3_12.
  7. Panwar, SS, Prasad, K., Umasankar Patro, T., Balasubramanian, K. & Venkataraman, B. On the occurrence of dynamic deformation aging in the alloy based on C-103 Nb. Materials Science and Engineering: A 620, 286-292 (2015).
  8. Alloy C-103 Nb: Properties and applications. HC Starck Solutions (2020).

This information was obtained, reviewed and adapted from documents provided by HC Starck Inc.

For more information on this source, please visit HC Starck Inc.

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