W75Cu25 INF (Press-sinter-infiltrated)
Heat-treated state · default condition
ASTM B694
Pick the press-sinter-infiltrated standard contact grade (ASTM B702 Class 75W) when arc erosion resistance must balance 200 W/m·K conduction, for HV switch contacts and general EDM electrodes.
Values for the INF condition
Other W75Cu25 grades and fills
W75Cu25 is listed in 4 conditions; see the grade overview at W75Cu25.
Compare all 4 grades and fillsHide
| Grade · open for datasheet | Best for | Yield MPa | Tensile MPa | Elong. % | Hardness |
|---|---|---|---|---|---|
INFDefaultThis page Press-sinter-infiltrated | Pick the press-sinter-infiltrated standard contact grade (ASTM B702 Class 75W) when arc erosion resistance must balance 200 W/m·K conduction, for HV switch contacts and general EDM electrodes. | 380 | 620 | 5 | — |
Activated press-and-sinter | Use the lower-cost Ni/Co-activated press-and-sinter route when 650 MPa strength matters more than conduction; activator dissolved in the copper cuts thermal conductivity to 165 W/m·K. | 420 | 650 | 3 | — |
Hot isostatic pressed | Pick hot isostatically pressed stock for microwave tubes, IGBT and laser heat sinks and package bases: closed porosity below 0.5% gives the best conduction (215 W/m·K) and hermeticity. | 420 | 680 | 6 | — |
Fine-grain / high-uniformity EDM electrode grade | Choose the 1–3 µm fine-tungsten infiltrated grade for precision EDM electrodes and micro cavities: the uniform structure polishes to a mirror finish, at 190 W/m·K and 3% elongation. | 450 | 700 | 3 | — |
What is W75Cu25 INF?
W75Cu25 INF is W75Cu25 heat treated to INF — pick the press-sinter-infiltrated standard contact grade (ASTM B702 Class 75W) when arc erosion resistance must balance 200 W/m·K conduction, for HV switch contacts and general EDM electrodes. W75Cu25 INF has a yield strength of 380 MPa (55.1 ksi) and a tensile strength of 620 MPa (89.9 ksi) — stronger than 63% of composite grades. Elongation at break is 5% and the elastic modulus is 250 GPa (36.3 Msi). W75Cu25 INF has a density of 14.8 g/cm³ (0.535 lb/in³), heavier than 100% of composite grades.
Advantages
- Conducts heat well — 200 W/m·K (115.6 BTU/hr·ft·°F), better than 97% of composite grades
- Polishes to a fine finish — 70/100, better than 94% of composite grades
- Good UV / weathering resistance — 100/100, better than 93% of composite grades
- Stiff — 250 GPa (36.3 Msi), better than 87% of composite grades
- Ductile — tolerates forming and impact — 5%, better than 86% of composite grades
Limitations
- Heavy — 14.8 g/cm³ (0.535 lb/in³), worse than 100% of composite grades
- Needs corrosion protection — 50/100, worse than 92% of composite grades
W75Cu25 INF properties
Typical room-temperature values for W75Cu25 INF; 14 are specific to this condition. Other listed values are W75Cu25 reference data and may not represent this condition. Bars are the position among composite grades.
Physical1
W75Cu25 INF has a density of 14.8 g/cm³ (0.535 lb/in³), heavier than 100% of composite grades.
Mechanical11
W75Cu25 INF has a yield strength of 380 MPa (55.1 ksi) and a tensile strength of 620 MPa (89.9 ksi) — stronger than 63% of composite grades. Elongation at break is 5% and the elastic modulus is 250 GPa (36.3 Msi).
Thermal6
W75Cu25 INF is rated for continuous service to 400°C (752 °F). It conducts heat at 200 W/m·K (115.6 BTU/hr·ft·°F), better than 97% of composite grades. Thermal expansion is 9.5 µm/m·K (5.28 µin/in·°F).
Electrical2
W75Cu25 INF has an electrical resistivity of 4×10⁻⁸ Ω·m.
Chemical & Environmental3
Corrosion resistance is fair (50/100), worse than 92% of composite grades. UV resistance is excellent.
Sustainability4
Producing a kilogram of W75Cu25 INF takes about 280 MJ of energy and emits 18 kg of CO₂ — more than 63% of composite grades. Typical recycled content is 20%.
Manufacturability2
W75Cu25 INF's machinability is poor (30/100, worse than 54% of composite grades).
Common Calculations5
Values are nominal handbook figures for design screening. Confirm any required mill or lot documentation when quoting.
Working with W75Cu25 INF
Is W75Cu25 easy to machine?
The tungsten phase is strongly abrasive; use sharp carbide or PCD tooling at low speed with a heavier feed and ample coolant. Deep cavities and precision forms are better produced by wire EDM or form grinding.
Can W75Cu25 be welded?
Not fusion weldable — the copper phase melts out and the tungsten does not melt. Braze with BAg silver-copper or Cu-P fillers in vacuum or hydrogen, or resistance-braze onto copper or steel carriers.
Can W75Cu25 be formed, bent or molded?
No cold forming capability. Parts are made net-shape by powder metallurgy (press, sinter, infiltrate), with complex geometry produced by machining or by the PM die shape.
What surface finishes work on W75Cu25?
Ni, Ag or Au plating improves joinability and corrosion resistance. EDM electrode faces are ground or lapped to Ra below 0.4 µm; the material is not suitable for anodizing.
W75Cu25 chemical composition (wt %)
Limits by weight percent from the governing specification, written the way the spec states them — a single maximum for impurities, a range for alloying elements, and the base element as balance. Nominal is the typical mid-range value.
| Element | Spec limit (wt %) | Nominal |
|---|---|---|
| Wtungsten skeleton, about 58 vol% | 73 – 77 | 75 |
| Nisintering activator, activated-sintered (PS) grades only | 0 – 0.5 | — |
| Feimpurity | 0 – 0.2 | — |
| other impurities (total)total of C, O, Si and other impurities | 0 – 0.5 | — |
| Cuinfiltrated copper phase, balance | ≥ 23 (balance) | — |
W75Cu25 INF — frequently asked
What is W75Cu25 INF used for?
W75Cu25 INF is typically used for circuit breaker contacts, EDM electrodes, vacuum interrupter contacts and welding electrode tips. In short: arc-erosion contact material; standard EDM electrode grade; very high density.
What is the yield strength of W75Cu25 INF?
W75Cu25 INF has a typical yield strength of 380 MPa (55.1 ksi) and a tensile strength of 620 MPa (89.9 ksi) — stronger than 63% of composite grades. Strength varies by condition: see the 4 listed tempers.
Is W75Cu25 INF easy to machine?
Not especially — machinability is rated poor (30/100, worse than 54% of composite grades). The tungsten phase is strongly abrasive; use sharp carbide or PCD tooling at low speed with a heavier feed and ample coolant. Deep cavities and precision forms are better produced by wire EDM or form grinding.
Can W75Cu25 INF be welded?
Not fusion weldable — the copper phase melts out and the tungsten does not melt. Braze with BAg silver-copper or Cu-P fillers in vacuum or hydrogen, or resistance-braze onto copper or steel carriers.
What surface finishes work on W75Cu25 INF?
Ni, Ag or Au plating improves joinability and corrosion resistance. EDM electrode faces are ground or lapped to Ra below 0.4 µm; the material is not suitable for anodizing.
Can W75Cu25 INF be formed, bent or molded?
No cold forming capability. Parts are made net-shape by powder metallurgy (press, sinter, infiltrate), with complex geometry produced by machining or by the PM die shape.
What is the maximum service temperature of W75Cu25 INF?
W75Cu25 INF is rated for continuous use to about 400°C (752 °F), and briefly to 1,000°C. Strength falls off well before that limit — check the elevated-temperature data for load-bearing parts.
What is the difference between W75Cu25 INF and W75Cu25 FG?
INF is the default condition — pick the press-sinter-infiltrated standard contact grade (ASTM B702 Class 75W) when arc erosion resistance must balance 200 W/m·K conduction, for HV switch contacts and general EDM electrodes. FG: choose the 1–3 µm fine-tungsten infiltrated grade for precision EDM electrodes and micro cavities: the uniform structure polishes to a mirror finish, at 190 W/m·K and 3% elongation. Yield strength is 380 MPa in INF versus 450 MPa in FG.
Sources
- ASTM B702 — Copper-Tungsten Electrical Contact Material — ASTM International (2016)
- ASM Handbook Vol.7: Powder Metallurgy (infiltrated W-Cu) — ASM International (2015)
- Tungsten-Copper (W-Cu) material data — Plansee / Mi-Tech Metals (2023)
Property data is compiled from published supplier and standards handbooks and normalised for comparison. Nothing on this page is a certification — request mill certs, CoC or material test reports with your order.