Tungsten grades / Tungsten heavy alloy W-Ni-Cu

Tungsten Heavy Alloy, W-Ni-Cu

The non-magnetic version of tungsten heavy alloy. Same tungsten content and density range as W-Ni-Fe, with copper standing in for iron in the binder.

W-Ni-Cu heavy alloy is 90 to 97% tungsten by weight, bound with nickel and copper instead of nickel and iron. Removing the iron is what removes the magnetism; everything else about the material, including the ASTM B777 class system, carries over from standard heavy alloy. A mill defaults to W-Ni-Fe unless the order specifies W-Ni-Cu, so this grade has to be stated explicitly on the drawing or RFQ, not assumed.

Property	Typical value
Density	17.0 to 18.0 g/cm³, typical
Hardness	Roughly low 20s to low 30s HRC, typical, close to W-Ni-Fe
Magnetic behavior	Effectively non-magnetic; permeability typically 1.0005 to 1.05 mu
Typical tolerance	±0.01 to ±0.025 mm, tighter by grinding

Typical density

W-Ni-Cu heavy alloy runs 17.0 to 18.0 g/cm³, typical, in the same range as W-Ni-Fe at a comparable ASTM B777 class. Swapping the binder from iron to copper does not meaningfully change the density; it changes the magnetic behavior.

Hardness

Hardness sits in roughly the same low 20s to low 30s HRC range as W-Ni-Fe, typical, since hardness in heavy alloy comes from the sintered tungsten-binder microstructure rather than from which binder metal is used. As with W-Ni-Fe, there is no field heat treatment that meaningfully increases this hardness the way tempering does for tool steel.

Magnetic or non-magnetic

This is the property W-Ni-Cu exists for. Standard W-Ni-Fe carries mild magnetism from its iron content; W-Ni-Cu is formulated to be effectively non-magnetic instead. But a nominally non-magnetic alloy is not the same as a tested part. Sintering variation batch to batch, and cold work from machining, grinding or clamping, can locally shift a part's magnetic response even when the bulk material is fine. Shops verify this with a quick magnet-pull check for gross errors, or with an instrument-based permeability meter, typically reading 1.0005 to 1.05 mu, for a documented result. If your application genuinely needs verified non-magnetic performance rather than just the correct alloy on the drawing, ask which verification method the shop uses and request a written report tied to your part.

How it machines

W-Ni-Cu machines the same way W-Ni-Fe does: like hard gray cast iron, turning, milling, drilling and tapping on standard CNC equipment with carbide tooling. The binder swap from iron to copper does not add machining difficulty. The same practical differences from cutting steel apply, faster tool wear from the abrasive tungsten grains, and part weight over twice the same shape in steel that affects workholding.

Typical achievable tolerance

±0.01 to ±0.025 mm is common on turned and milled features, typical, the same range as W-Ni-Fe. Tighter faces or bores are finished by grinding after the main machining operations.

ASTM B777 classes

The same four B777 classes apply, defined by minimum tungsten content and density, and each can be supplied with either binder system. The class number sets density and mechanical properties; the binder choice, W-Ni-Fe or W-Ni-Cu, sets magnetism. State both on your RFQ: the class or target density, and W-Ni-Cu explicitly if a stray field near the part is a real constraint.

Typical applications

Shielding and fixtures used near MRI equipment or other strong-field instruments
Electron beam and other magnetically sensitive lab or process equipment
Non-magnetic counterweights and ballast near sensors or navigation instruments
Sensor housings and enclosures where a magnetic part would disturb the reading

Sources

Have a non-magnetic heavy alloy part to source? Get matched with a shop that cuts this grade.