Mo Molybdenum

W Tungsten
Ta Tantal
W-MMC Metal Matrix Composites

Tungsten: Properties and use

Tungsten has the highest melting point of all metals as well as a remarkably high modulus of elasticity. Thanks to its outstanding thermal properties, tungsten can easily withstand even the highest temperatures. Tungsten also stands out for its relatively high density and is therefore used in a wide range of industrial applications such as in the aviation and aerospace industries, the electrical engineering sector, and in electronics.

Find out more about the properties of tungsten as well as its alloys, applications, and Plansee products made of tungsten.

Key facts about tungsten

Atomic number	74
CAS number	7440-33-7
Atomic mass	183.84 [g/mol]
Melting point	3420 °C
Boiling point	5555 °C
Density at 20 °C	19.25 [g/cm³]
Crystal structure	Body-centered cubic
Coefficient of linear thermal expansion at 20 °C	4.4 × 10^-6 [m/(mK)]
Thermal conductivity at 20 °C	164 [W/(mK)]
Specific heat at 20 °C	0.13 [J/(gK)]
Electrical conductivity at 20 °C	18.2 × 10⁶ [S/m]
Specific electrical resistance at 20 °C	0.055 [(Ωmm²)/m]

Advantages

Advantages of tungsten

Our tungsten is used in very special industrial applications that reflect the unique properties of this material. The following sections offer a brief insight into three of these applications:

Outstanding creep resistance and high purity
Our tungsten is very popular for use in vessels for melting and solidifying in the field of sapphire crystal growth. Its high level of purity prevents any contamination of the sapphire crystal and its good creep resistance guarantees the product's dimensional stability. The results of the process remain stable even at extremely high temperatures.
High purity and good electrical conductivity
With the lowest coefficient of thermal expansion of all metals and a high level of electrical conductivity, our tungsten is the perfect material for thin-film applications. Its high level of electrical conductivity and low diffusivity to neighboring layers mean that tungsten is an important component in thin-film transistors of the sort that are used in TFT LCD screens. And, of course, we are also able to supply you with the coating material in the form of ultra-high purity sputtering targets. No other manufacturer is able to supply tungsten targets in larger dimensions.
Long service life and an extremely high melting point
With their long service lives even at extremely high temperatures, our tungsten crucibles and mandrel shafts are able to withstand even quartz glass melts without difficulty. Thanks to the outstanding purity of our tungsten, we can reliably prevent any bubble formation or discoloration of the quartz melts.

Applications

What is tungsten used for?

Its special properties make tungsten an important material for high-performance applications.

Tungsten is used in a wide range of industries, including aviation and aerospace, electronics, manufacturing technology, and medical technology. Tungsten comes into play for components that require a high degree of temperature resistance in these sectors, such as rocket nozzles, high-temperature furnace components, and lamp components. In the electronics industry, tungsten is used for electrical contacts and electrodes due its high melting point and low thermal expansion. Tungsten is also used for various applications in medical technology, such as generating X-rays and providing radiation protection.

Here's a quick look at tungsten applications and our products that use this material:

Properties

Tungsten: Properties

Tungsten has the highest melting point of all metals as well as a remarkably high modulus of elasticity. In general, its properties are similar to those of molybdenum. These two metals are located in the same group in the periodic table. However, some of the properties of tungsten are more pronounced than they are in molybdenum. Thanks to its outstanding thermal properties, tungsten can easily withstand even the most intense heat.

We are able to influence the properties of our tungsten and its alloys by varying the type and quantity of alloying elements that we add as well as the production process we employ.

We primarily use doped tungsten materials. For WVM, we add small quantities of potassium. Potassium has a positive effect on the mechanical properties of tungsten, especially at high temperatures. The addition of La₂O₃ ensures a decrease of the electron work function along with better mechanical workability, making tungsten suitable for use as a cathode material.

We add rhenium in order to increase the ductility of our tungsten. Copper increases the material's electrical conductivity. Thanks to their good workability, you can also use our heavy metal alloys for complex geometries. They can be used as shielding material or as damping and absorption components, for example.

What are the physical properties of tungsten?
Tungsten has the highest melting point of all refractory metals, a low thermal coefficient of expansion, and a relatively high density. The good electrical conductivity and the excellent thermal conductivity of tungsten should also be mentioned. All of these properties are more pronounced in tungsten than in molybdenum. Tungsten is located in the same group in the periodic table, but one period lower than molybdenum.

The physical properties of tungsten change with temperature. The diagrams below illustrate the curves for the most important scales for a comparison:
Vapor pressures of refractory metals
Coefficient of linear thermal expansion of tungsten and molybdenum
Heat capacity of tungsten and molybdenum
Specific electrical resistance of tungsten and molybdenum
Thermal conductivity of tungsten and molybdenum
Temperature-dependent value of emissivity for W
The graph (top right) summarizes the temperature-dependent values of emissivity of tungsten (shown as blue scatter band) available in the literature. Experimentally measured values of emissivity of Plansee samples in typical as-delivered condition can be found on the upper end of the scatter band.

What are the mechanical properties of tungsten?

We optimize the material purity, determine the type and quantity of alloying components, and modify the microstructure of our tungsten through targeted thermomechanical treatment, a combination of deforming and heat treatment. This results in customized mechanical properties for the most diverse applications. Tungsten has similar mechanical properties to molybdenum. Like with molybdenum, these properties are dependent on the testing temperature. At 3420 °C, tungsten has the highest melting point of all metals. The material's excellent high-temperature stability coupled with its high modulus of elasticity give tungsten its high creep resistance.

Modulus of elasticity of tungsten plotted against the testing temperature compared to our other refractory metals.

Like molybdenum, tungsten has a body-centered cubic lattice and therefore the same characteristic brittle-to-ductile transition. The brittle-to-ductile transition temperature can be reduced by means of forming and alloying. The strength of the material increases with an increasing degree of deformation. However, unlike other metals, this also increases the ductility of tungsten. The main alloy element used to improve the overall ductility of tungsten is rhenium.

Doping:

The term "doping" comes from the Latin "dotare" and means "provide with". In the world of metallurgy, doping refers to the introduction of one or more alloying elements in the microgram range. The term "microalloying" is also often used. The alloy content introduced during doping may reach several hundred micrograms. The amount of doping quantity is frequently given in ppm (ppm by weight). The abbreviation ppm stands for "parts per million", i.e., 10^-6.

If you are intending to use tungsten at high temperatures, you should take account of the material's recrystallization temperature. When it comes to tungsten materials, the ductility, in particular, along with the strength of the material decreases with a rising recrystallization level. Doping with small oxide particles (e.g., lanthanum oxide or cerium oxide) increases the recrystallization temperature and creep resistance of tungsten. The higher the deformation, the stronger the effect when it comes to the oxide, which becomes finer due to the thermomechanical processing.

The table indicates the recrystallization temperatures of our tungsten-based materials at different levels of deformation:

Material	Temperature [°C] for 100% recrystallization (annealing time: 1 hour)
	Level of deformation = 90%	Level of deformation = 99.99%
W (pure)	1350	-
WVM	-	2000
WL10	1500	2500
WL15	1550	2600
WRe05	1700	-
WRe26	1750	-

Typical 0.2% yield strength values for W- and Mo sheet material in the stress relieved and/or recrystallized condition (sheet thickness: W = 1 mm / Mo = 2 mm)
Typical tensile strength values for W- and Mo sheet material in the stress relieved and/or recrystallized condition (sheet thickness: W = 1 mm / Mo = 2 mm)
Typical 0.2% yield strength values for W- and Mo rod material in the stress relieved and/or recrystallized condition (diameter: 25 mm)
Typical tensile strength values for W- and Mo rod material in the stress relieved and/or recrystallized condition (diameter: 25 mm)

The machining of tungsten requires a real feeling for the material. Chipless forming processes such as bending or folding must generally be applied at above the brittle-to-ductile transition temperature. In the case of tungsten, this temperature is higher than for molybdenum. The thicker the sheets that are to be processed, the higher the required preheating temperature. The sheets need a higher preheating temperature for cutting and punching than for folding operations. It is very difficult to use machining processes with tungsten. Our tungsten alloys using lanthanum oxide are somewhat easier to machine. However, the level of tool wear is still very considerable and chipping may occur. If you have any specific questions relating to the machining of refractory metals, we would be glad to assist you with our many years of experience.

What is the chemical behavior of tungsten?

Tungsten is corrosion-resistant at a relative humidity of under 60%. In moister air, discoloration starts to occur. However, this is less pronounced than in molybdenum. Even at very high temperatures, glass melts, hydrogen, nitrogen, noble gases, metal melts, and oxide ceramic melts are largely unaggressive to tungsten provided that they do not also contain oxidants.

The table below indicates the corrosion behavior of tungsten. Unless otherwise indicated, the specifications relate to pure solutions not mixed with air or nitrogen. Tiny concentrations of extraneous chemically active substances can significantly affect the corrosion behavior. Do you have any questions regarding complex corrosion-related topics? We would be delighted to help you with our experience and our in-house corrosion laboratory.

MEDIUM	RESISTANT (+), NON-RESISTANT (-)	NOTE
Water
Cold and warm water < 80 °C	+
Hot water > 80 °C, deaerated	+
Steam up to 700 °C	+
Acids
Hydrofluoric acid, HF	+	< 100 °C
Hydrochloric acid, HCI	+
Phosphoric acid, H₃PO₄	+	< 270 °C
Sulfuric acid, H₂SO₄	+	< 70%, < 190 °C
Nitric acid, HNO₃	+
Nitro hydrochloric acid, HNO₃ + 3 HCl	+	< 30 °C
Organic acids	+
Lyes
Ammonia solution, NH₄OH	+
Potassium hydroxide, KOH	+	< 50%, < 100 °C
Sodium hydroxide, NaOH	+	< 50%, < 100 °C
Halogens
Fluorine, F₂	-
Chlorine, Cl₂	+	< 250 °C
Bromine, Br₂	+	< 450 °C
Iodine, I₂	+	< 450 °C
Non-metals
Borine, B	+	< 1200 °C
Carbon, C	+	< 1200 °C
Silicon, Si	+	< 900 °C
Phosphorous, P	+	< 800 °C
Sulfur, S	+	< 500 °C
Gases*
Ammonia, NH₃	+	< 1000 °C
Carbon monoxide, CO	+	< 1400 °C
Carbon dioxide, CO₂	+	< 1200 °C
Hydrocarbons	+	< 1200 °C
Air and oxygen, O₂	+	< 500 °C
Noble gases (He, Ar, N₂)	+
Hydrogen, H₂	+
Water vapor	+	< 700 °C
*Special attention must be paid to the dew point of the gases. Moisture can lead to oxidation.
Melts
Glass melts*	+	< 1700 °C
Aluminum, Al	+	< 700 °C
Beryllium, Be	-
Bismuth, Bi	+	< 1400 °C
Cesium, Cs	+	< 1200 °C
Cer, Ce	+	< 800 °C
Copper, Cu	+	< 1300 °C
Europium, Eu	+	< 800 °C
Gallium, Ga	+	< 1000 °C
Gold, Au	+	< 1100 °C
Iron, Fe	-
Lead, Pb	+	< 1100 °C
Lithium, Li	+	< 1600 °C
Magnesium, Mg	+	< 1000 °C
Mercury, Hg	+	< 600 °C
Nickel, Ni	-
Plutonium, Pu	+	< 700 °C
Potassium, K	+	< 1200 °C
Rubidium, Rb	+	< 1200 °C
Samarium, Sm	+	< 800 °C
Scandium, Sc	+	< 1400 °C
Silver, Ag	+
Sodium, Na	+	< 600 °C
Tin, Sn	+	< 980 °C
Uranium, U	+	< 900 °C
Zinc, Zn	+	< 750 °C
Furnace construction materials
Alumina, Al₂O₃	+	< 1900 °C
Beryllium oxide, BeO	+	< 2000 °C
Graphite, C	+	< 1200 °C
Magnesite, MgCO₃	+	< 1600 °C
Magnesium oxide, MgO	+	< 1600 °C
Silicon carbide, SiC	+	< 1300 °C
Zirconium oxide, ZrO₂	+	< 1900 °C

Corrosion behavior of tungsten against selected substances

Range of materials

Pure tungsten or maybe an alloy? We're happy to advise you!

You can rely on our quality. We produce our tungsten products from the metal powder to the finished product. We only use the purest tungsten oxide as the source material. This is how we can guarantee you a very high material purity. We guarantee a purity of 99.97% for our tungsten (metallic purity without Mo). The remaining portion is made up primarily of the following elements:

Element	Typical max. value [μg/g]	Guaranteed max. value [μg/g]
Al	1	15
Cr	3	20
Cu	1	10
Fe	8	30
K	1	10
Mo	12	100
Ni	2	20
Si	1	20
C	6	30
H	0	5
N	1	5
O	2	20
Cd	1	5
Hg	0	1
Pb	1	5

The presence of Cr (VI) and organic impurities can be excluded definitely because of the production process (multiple heat treatment at temperatures above 1 000 °C in H2-atmosphere).

Material designation		Chemical composition (percent by weight)
W (pure)		> 99.97% W
W-UHP (ultra-pure)		> 99.9999% W
WVM		30–70 μg/g K
WVMW		15–40 μg/g K
WL	WL05 WL10 WL15 WL20	0.5% La₂O₃ 1.0% La₂O₃1.5% La₂O₃2.0% La₂O₃
WC20		2.0% CeO₂
WRe	WRe05 WRe26	5.0% Re 26.0% Re
WCu*		10 - 40% Cu
W heavy metal* alloy with a high density	Densimet® Inermet® Denal®	1.5% - 10% Ni, Fe, Mo 5% - 10% Ni, Cu 2.5% - 10% Ni, Fe, Co

* Detailed information on our tungsten-based metal matrix composites can be found on the materials page on W-MMC

We optimally prepare our tungsten for its special application. We define the following properties due to various alloying additions:

Physical properties (e.g., melting point, density, electrical conductivity, thermal conductivity, thermal expansion, electron work function)
Mechanical properties (e.g., strength, creep behavior, ductility)
Chemical properties (corrosion resistance, etching behavior)
Workability (machinability, formability, welding suitability)
Recrystallization behavior (recrystallization temperature)

And we don't stop there: we can also vary the tungsten properties in other areas due to tailor-made manufacturing processes. The result: Tungsten alloys with different property profiles that are customized to the respective application.

Tungsten alloys

WVM (tungsten-vacuum-metallizing)
WVM is almost pure tungsten doped with only a tiny amount of potassium. We primarily supply our WVM in rod and wire form. It is used as evaporation coils or heating filaments as well as for the production of components for epitaxial processes. It can also be used as a sheet in the form of an evaporation boat. We use doping as well as proper thermomechanical treatment to create a stacked structure, which results in increased dimensional stability at high temperatures.
WVMW (WVM-tungsten)
WVMW and S-WVMW were developed for use as anode materials for short arc lamps with diameters greater than 15 mm. We use almost pure tungsten for both materials, which is doped with potassium. S-WVMW is particularly suitable for rod diameters greater than 30 mm. Thanks to the special production process we use to manufacture S-WVMW, we are able to achieve high densities in the rod core.
WL (tungsten-lanthanum oxide)
We mix our tungsten with 0.5, 1.0, 1.5, or 2.0 percent of lanthanum oxide (La₂O₃) by weight in order to improve its creep resistance and increase the recrystallization temperature. Our WL is also easier to machine due to the finely distributed oxide particles in its structure. The electron work function of tungsten-lanthanum oxide is significantly lower than that of pure tungsten. That's why WL is a popular choice for ion sources and lamp electrodes.
WC20 (tungsten-cerium oxide)
WC20 is used as the welding electrode material. We dope tungsten with two percent cerium oxide by weight to obtain a material with a lower electron work function, better ignition characteristics, and a longer service life than pure tungsten.
WRe (tungsten-rhenium)
We alloy our tungsten with rhenium to obtain greater ductility and a lower brittle-to-ductile transition temperature. In addition, tungsten-rhenium also has a higher recrystallization temperature and better creep resistance. We use the WRe standard compositions – WRe05 and WRe26 – as a thermoelement material in applications up to over 2000 °C. This material is also used in the aviation and aerospace industries.

Tungsten alloys compared to pure tungsten


	W	WVM	WL
Alloying components (as a percent by weight)	99.97% W	30–70 μg/g K	0.5% La₂O₃ 1.0% La₂O₃ 1.5% La₂O₃2.0% La₂O₃
Thermal conductivity	∼	∼	∼
High-temperature stability / Creep resistance	∼	++ +	+
Recrystallization temperature	∼	++	+
Fine-grained structure	∼	+	+
Ductility	∼	+	+
Workability/formability	∼	+	++
Electron work function	∼	∼	--

∼ comparable with pure W + higher than pure W ++ much higher than pure W - lower than pure W -- much lower than pure W


	WC20	WRe	WCu
Alloying components (as a percent by weight)	2% CeO₂	5% / 26% Re	10–40% Cu
Thermal conductivity	∼	-	+
High-temperature stability / Creep resistance	+	+	--
Recrystallization temperature	+	+
Fine-grained structure	+	∼
Ductility	+	++	++
Workability/formability	++	+	++
Electron work function		+

∼ comparable with pure W + higher than pure W ++ much higher than pure W - lower than pure W -- much lower than pure W

Contact

If you have any questions or are looking for a suitable material composition for your application, get in touch with us!

Deposits

Sustainable procurement of tungsten

Where does tungsten occur naturally?

Tungsten was first found in the Ore Mountains of central Europe in the Middle Ages during the process of tin reduction. However, at that time it was considered to be an unwanted accompanying element. The tungsten ore facilitated slag formation during the reduction of tin and consequently impaired the yield. The German name for tungsten (Wolfram = "wolf's drool") comes from its reputation as a tin-devouring ore "It consumes tin as a wolf eats sheep". In 1752, the chemist Axel Fredrik Cronstedt discovered a heavy metal which he named "Tung Sten," Swedish for "heavy stone". It was not until 30 years later that Carl Wilhelm Scheele succeeded in producing tungstic acid from the ore. And just two years after that, Scheele's two assistants, the brothers Juan Jose and Fausto de Elhuyar, reduced tungsten trioxide to produce tungsten. Nowadays, these two brothers are considered to be the true discoverers of tungsten. The name "Wolframium" and the accompanying symbol W were proposed by Jöns Jakob Berzelius.

Tungsten ore occurs naturally most frequently in the form of wolframite ((Fe/Mn)WO₄) and scheelite (CaWO₄). The largest deposits of tungsten are found in China, Russia, and the USA. In Austria, there is also a scheelite deposit in Mittersill in the Felbertauern district.

Depending on the deposit, these tungsten ores have a WO₃ content of between 0.3 and 2.5 percent by weight. Comminution, grinding, flotation, and roasting processes can be employed to increase the WO₃ content to approximately 60%. The remaining impurities are mostly eliminated by means of digestion with sodium hydroxide. The sodium tungstate that is obtained from this is transformed into APT (ammonium paratungstate) using a so-called ion exchange extraction process.

Reduction is performed in a hydrogen atmosphere at temperatures between 500 and 1000 °C:

WO₃ + 3H₂ › W + 3H₂O

Global Tungsten Powders (GTP), a Plansee Group company, supplies our tungsten powder. Thanks to its advanced recycling technology, GTP has the capacity to process many different types of tungsten scrap. This plays a key role in our sustainable raw material supply.

To GTP

RMAP Compliant Procurement

Tungsten is partially mined in regions that are considered conflict and high-risk areas and is therefore classified as a "conflict mineral." As a company aware of its responsibilities, we take particular care when sourcing raw materials.

Based on a wide range of measures such as the Responsible Minerals Initiative (RMI) certification, we ensure that we do not source or use any raw materials from socially, ethically, or ecologically questionable sources.

That is why we take on the voluntary obligation to verify the "conflict-free" origin of our tungsten with its own certificate. In this, the Responsible Minerals Initiative (RMI) certifies that Plansee uses tungsten raw materials from ethically irreproachable sources. The audit committee of the Responsible Business Alliance (RBA) and the Global e-Sustainability Initiative (GeSI) has confirmed that Global Tungsten & Powders (GTP) in Towanda – a Plansee Group company – sources tungsten in compliance with the RMAP. For Plansee's customers, this certificate provides independent proof that the Plansee Group procures its tungsten from responsible sources.

More about sustainability at Plansee

Production process

Producing tungsten using the powder metallurgy process

Powder metallurgy allows us to produce materials with melting points of well over 2000 °C. This process is particularly economical even when only small quantities are produced. By using tailor-made powder mixes, we are also able to produce a range of extremely homogeneous materials endowed with specific properties.

The tungsten powder is mixed with the possible alloying elements and then primarily compacted in a cold isostatic manner. The pressure used here is up to 2000 bar. The resulting pressed blank (also known as a "green compact") is then sintered in special furnaces at temperatures of over 2000 °C. During this process, it acquires its density and its microstructure forms. The very special properties of our materials – such as their excellent high-temperature stability and hardness or their flow characteristics – are due to the use of the appropriate forming methods, for example, forging, rolling, or drawing. Only when all these steps dovetail perfectly can we achieve our exacting quality demands and manufacture products of outstanding purity and quality.

Oxide

Reduction

Mixing alloys

Pressing

Sintering

Forming

Heat treatment

Mech. processing

Quality assurance

Recycling

OxideMolymet (Chile) is the world's largest processor of molybdenum ore concentrates and our main supplier of molybdenum trioxide. The Plansee Group holds a 21.15% share in Molymet. Global Tungsten & Powders (USA) is a division of the Plansee Group and our main supplier of tungsten metal powder.

Product range

Overview of semifinished products made of tungsten and tungsten alloys

The table provides an overview of our semifinished products made of tungsten. Some of these semifinished products come in a specific thickness or specific range of diameters, while others are available on request.
Material	Sheets and plates [thickness]	Rods [diameter]	Wires [diameter]
W	0.025–20 mm	0.3–90 mm	0.025–1.50 mm
W-UHP	Upon request
WVM	0.05–5 mm	0.3–12.99 mm	0.050–1.50 mm
WVMW		13–45 mm
WL05/WL10/WL15	Upon request	0.3 – 90 mm
WC20		Upon request
WRe05/WRe26		Upon request	0.4–1.50 mm

Online shop

Tungsten products in the Plansee online shop

You can order sheets, rods, ribbons, and wires as well as other products in configurable dimensions made of tungsten and tungsten alloys quickly and easily in our online shop.

Take a look at our products in the Plansee online shop

Downloads

Tungsten material brochure and data sheets

Would you like to learn more about tungsten and its alloys? Then please see our material brochure and product data sheets here.

Material brochure: Tungsten

Product data sheet: W

Product data sheet WC

Product data sheet: WRe

FAQs

Frequently asked questions regarding tungsten

What are the applications of tungsten?
With its unique mechanical and chemical properties, tungsten is an outstanding material that can meet the most exacting requirements. We use this material to make high-temperature furnace components, lamp components as well as components for medical and thin film technology.
Where does the name wolfram/tungsten come from?
Tungsten was first found in the Ore Mountains of central Europe in the Middle Ages during the process of tin reduction. However, at that time it was considered to be an unwanted accompanying element. The tungsten ore facilitated slag formation during the reduction of tin and consequently impaired the yield. The German name for tungsten (Wolfram = "wolf's drool") comes from its reputation as a tin-devouring ore "It consumes tin as a wolf eats sheep". In 1752, the chemist Axel Fredrik Cronstedt discovered a heavy metal which he named "Tung Sten," Swedish for "heavy stone". It was not until 30 years later that Carl Wilhelm Scheele succeeded in producing tungstic acid from the ore. And just two years after that, Scheele's two assistants, the brothers Juan Jose and Fausto de Elhuyar, reduced tungsten trioxide to produce tungsten. Nowadays, these two brothers are considered to be the true discoverers of tungsten. The name "Wolframium" and the accompanying symbol W were proposed by Jöns Jakob Berzelius.
Where is tungsten mined?
Tungsten ore occurs naturally most frequently in the form of wolframite ((Fe/Mn)WO₄) and scheelite (CaWO₄). The largest deposits of tungsten are found in China, Russia, and the USA. In Austria, there is also a scheelite deposit in Mittersill in the Felbertauern district.