MATERIAL COMPARISON
A heavy-alloy specification is not a pure-tungsten specification.
For a compact counterweight or a machined component, the word tungsten is not a complete purchasing description. Decide whether the drawing requires pure tungsten or a defined heavy-alloy grade before comparing offers.
Comparison table
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| Criterion | Pure tungsten | WNiFe | WNiCu |
|---|---|---|---|
| Material identity | Tungsten metal; specify purity and form. | W with a nickel-iron matrix. | W with a nickel-copper matrix. |
| Reference or example | MTS pure-W reference. | MTS example: MT-17F. | MTS example: MT-17C. |
| Density | Reference density at 20 °C: 19.3 g/cm³ Pure tungsten (W), MTS elemental reference; Midwest Tungsten Service. Pure tungsten at 20 °C. MTS elemental reference, not a batch result or finished-part acceptance limit. Source: Midwest Tungsten Service - Tungsten Metal (W) Properties (Web page; revision date not stated; checked 2026-10-11, p. Tungsten Properties / Density at 20C (gm/cc)). Reviewed: 2026-10-11. | Catalogue density: 17 g/cm³ MTS MT-17F (WNiFe); Midwest Tungsten Service. MTS MT-17F catalogue value only; measurement temperature is not stated. Not a universal value for all WNiFe grades or a batch acceptance limit. Source: Midwest Tungsten Service - Heavy Tungsten Alloys (Web page; revision date not stated; checked 2026-10-11, p. Heavy alloy material table / MT-17F / Density, grams/cubic centimeter). Reviewed: 2026-10-11. | Catalogue density: 17 g/cm³ MTS MT-17C (WNiCu); Midwest Tungsten Service. MTS MT-17C catalogue value only; measurement temperature is not stated. Not a universal value for all WNiCu grades or a batch acceptance limit. Source: Midwest Tungsten Service - Heavy Tungsten Alloys (Web page; revision date not stated; checked 2026-10-11, p. Heavy alloy material table / MT-17C / Density, grams/cubic centimeter). Reviewed: 2026-10-11. |
| Machining | More difficult than the heavy-alloy route described by MTS. | Conventional machining is possible. | Conventional machining is possible. |
| Magnetic behaviour | No magnetic acceptance value assigned here. | MT-17F is described as slightly magnetic. | MT-17C is listed with no magnetism; no test threshold is supplied. |
Scope of the comparison
MT-17F and MT-17C are examples, not all WNiFe and WNiCu grades. Their catalogue density entries do not specify product form, heat-treatment state or measurement temperature. These entries are not results of a comparison with pure W at a common measurement temperature, design minima or acceptance certificates. Agree a measurement method and limit if magnetic behaviour matters.
Selection conditions
- When the drawing requires pure W, a Ni-Fe or Ni-Cu matrix is a material change. Assess the thermal and chemical requirements before proposing it.
- For a machined weight, evaluate the offered heavy-alloy grade, achievable geometry and finished mass together. Do not estimate it using pure-W density.
- Where low magnetic response is essential, a named WNiCu grade may be a candidate; require an agreed magnetic test rather than treating “non-magnetic” as a universal certificate. WNiFe and WNiCu remain distinct options.
Sources for this table
Midwest Tungsten Service: pure tungsten, density at 20 °C (English)Midwest Tungsten Service: MT-17F and MT-17C catalogue data (English)References reviewed on 14 September 2026. Manufacturer references identify their own materials, not an MNK stock item or a supplier partnership.
The material distinction
Midwest Tungsten Service describes heavy alloys with nickel-iron or nickel-copper matrices and reports improved ductility and conventional machinability compared with pure tungsten. These are family-level descriptions, not acceptance values for your component.
Midwest Tungsten Service: heavy alloys (external source, English)
Identify the supplied material
A quotation described only as W leaves the material identity unclear. Request the exact pure-metal grade or heavy-alloy designation. If a binder family is specified, keep that requirement visible in the comparison.
Use the correct density
Do not apply the pure-tungsten reference density to an unspecified heavy alloy. For a weight estimate, use the density documented for the quoted grade and distinguish an estimate from the required finished-part mass.
Check the drawing context
A proposed heavy alloy is a material change when the drawing calls for pure tungsten. Where thermal behaviour or chemical compatibility matters, have the responsible engineer assess the substitution against the application requirements.
A focused inquiry for comparable offers
- Name the requested material and identify any proposed alternative separately.
- Keep the supply form, dimensions and quantity consistent across quotations.
- Use Technical Requirements / Notes for the drawing reference and the function that drives material selection.
- Ask the supplier to identify the data applicable to the delivered grade and condition; do not treat an unqualified typical value as a guaranteed acceptance result.
This comparison does not qualify a design, certify a delivered property or establish equivalence. It makes no universal price, stock, service-temperature or performance claim.
Continue with the material pages
Source reviewed: 14 September 2026. Original procurement guidance by MNK-G.S.A.