Tungsten heavy alloy is a liquid-phase sintered composite of tungsten grains in a nickel-iron or nickel-copper matrix. It combines a very high density with good machinability – unlike pure tungsten, it can be turned, milled and drilled.
Structure and key figures
Tungsten heavy alloy is 90–97% tungsten; the rest is a ductile matrix of nickel and iron (WNiFe) or nickel and copper (WNiCu). The higher the tungsten content, the higher the density (17.0 to 18.5 g/cm³). The matrix makes the material tough and machinable, while the tungsten grains provide density and stiffness. The grades are classified in ASTM B777.
Grades by tungsten content
The common classes per ASTM B777 differ mainly in tungsten content and therefore in density:
| Grade | Tungsten content | Density (g/cm³) | ASTM B777 |
|---|---|---|---|
| W90NiFe | 90% | ≈ 17.0 | Class 1 |
| W92.5NiFe | 92.5% | ≈ 17.5 | Class 2 |
| W95NiFe | 95% | ≈ 18.0 | Class 3 |
| W97NiFe | 97% | ≈ 18.5 | Class 4 |
| WNiCu | 90–95% | 17.0–18.0 | non-magnetic |
WNiFe or WNiCu?
WNiFe (nickel-iron matrix) has the higher strength and ductility and is the standard choice for balance weights and load-bearing parts. Due to the iron content it is slightly ferromagnetic, however. WNiCu (nickel-copper matrix) is non-magnetic and is chosen where magnetic neutrality is required – near sensitive sensors or measurement equipment, for example. Mechanically, WNiCu is somewhat weaker than WNiFe.
Typical applications
Balance and counterweights (aerospace, motorsport, machine tools), radiation shielding (collimators, syringe shields in nuclear medicine), vibration damping on tools and spindles, and counterweights where a lot of mass is needed in a small space. We stock DensM170 (≈ 17.0) and DensM175 (≈ 17.5); further grades are available on request.
Frequently asked questions
What do WNiFe and WNiCu mean?
The letters denote the composition: W = tungsten, Ni = nickel, Fe = iron, Cu = copper. WNiFe has a nickel-iron matrix, WNiCu a nickel-copper matrix.
Is tungsten heavy alloy magnetic?
WNiFe is slightly ferromagnetic because of its iron content. If magnetic neutrality is required, WNiCu is chosen, which is non-magnetic.
How heavy is tungsten heavy alloy?
Between 17.0 and 18.5 g/cm³ depending on tungsten content – more than twice as heavy as steel and close to pure tungsten (19.25 g/cm³), yet much easier to machine.
Can tungsten heavy alloy be machined?
Yes. Unlike pure tungsten, tungsten heavy alloy can be turned, milled and drilled thanks to its ductile matrix – for tight tolerances, carbide tooling is recommended.