Tungsten-Copper, Tungsten-Rhenium and Doped Tungsten
This group collects the tungsten materials that are neither pure metal, heavy alloy nor carbide. Tungsten-copper (W80Cu20, W70Cu30) is a pressed tungsten skeleton infiltrated with copper: 14–15.6 g/cm³, thermal conductivity around 200 W/m·K and expansion of 8–10 ppm/K, tuned to match alumina and semiconductor packages. Tungsten-rhenium (W-25Re) is the ductile tungsten, formable at room temperature. The doped TIG electrodes — EWLa-1 (WL15), EWTh-2 (WT20), EWZr-1 (WZ8) — and WVMA (Doped Non-Sag Tungsten) filament wire carry an oxide or potassium dopant that controls arc starting or high-temperature creep.
Popular specialty tungsten grades
Compare in the explorer| Grade | Yield, MPa | Tensile, MPa | Density, g/cm³ | Machinability | Weldability | Best for |
|---|---|---|---|---|---|---|
| W70Cu30 | 450 | 620 | 14 | Fair | Poor | EDM and resistance-welding electrodes, arcing contacts |
| W80Cu20 | 470 | 630 | 15.25 | Poor | Not recommended | Heat spreaders matched to alumina and silicon |
| W-25Re | 1,850 | 2,100 | 19.7 | Not recommended | Fair | Ductile thermocouple, filament and spring wire |
| WVMA (Doped Non-Sag Tungsten) | 1,900 | 2,200 | 19.3 | Not recommended | Poor | Lamp and heater filament wire |
| EWTh-2 | 1,150 | 1,400 | 19.1 | Not recommended | Not recommended | Best DC arc starting |
| EWCe-2 | 1,100 | 1,300 | 19.1 | Not recommended | Not recommended | Non-radioactive thoria substitute |
| EWZr-1 | 900 | 1,250 | 19.2 | Not recommended | Not recommended | Best AC aluminium electrode |
Choose specialty tungsten for
EDM and resistance-welding electrodes, vacuum-interrupter and high-current arcing contacts, heat sinks and package bases matched to ceramic and semiconductor expansion (W-Cu); thermocouples, filaments and springs that must survive above 2,000 °C and still bend cold (W-Re); TIG electrodes for every process and current type; and lamp and furnace filaments that must not sag over thousands of hours.
Look elsewhere when
The contact or electrode carries only moderate current, where C18200 chromium copper or a silver-based contact alloy is cheaper and more conductive; the heat sink does not need the expansion match (pure copper or aluminum conducts far better); the part is a bulk high-temperature component (Pure W or Pure Mo); or the thermocouple stays below 1,700 °C, where a platinum-rhodium type is more stable in air.
Loading the library…
Specialty tungsten by application
- Electrodes and contacts
- W70Cu30 for EDM electrodes cutting carbide and for spot-welding electrodes on steel and nickel; W80Cu20 and W70Cu30 for vacuum-interrupter and switchgear arcing contacts that must resist welding and erosion.
- Thermal management
- W80Cu20 and W70Cu30 as heat spreaders, package bases and flanges for RF power transistors and laser diodes, where the 8–10 ppm/K expansion matches the ceramic or die and 200 W/m·K carries the heat.
- High-temperature wire
- W-25Re for thermocouple legs, mass-spectrometer filaments and springs; WVMA (Doped Non-Sag Tungsten) for incandescent and halogen filaments and furnace heater coils that would creep in pure tungsten.
Working with specialty tungsten
- Machining
- Tungsten-copper machines with carbide tooling much like a hard bronze — the copper phase lubricates the cut — and holds ±0.01 mm; the higher the tungsten content, the more abrasive it gets. W-Re is ground or EDM-cut. Electrodes are ground to their tip geometry, not turned.
- Joining
- W-Cu brazes and solders readily to copper and steel because its surface is largely copper; use silver-based fillers and plate with nickel or gold for solder joints in electronics. W-Re welds to itself and to tungsten by electron beam or laser, and stays ductile at the joint where pure tungsten would not.
- Finishing
- Nickel or gold plating on W-Cu bases for solderability and corrosion resistance; electrodes are left bare. All tungsten materials oxidize above about 500 °C in air, so hot service is under vacuum or protective gas.
Other tungsten alloy series
Tungsten-Copper, Tungsten-Rhenium and Doped Tungsten — frequently asked
What is specialty tungsten?
This group collects the tungsten materials that are neither pure metal, heavy alloy nor carbide. Tungsten-copper (W80Cu20, W70Cu30) is a pressed tungsten skeleton infiltrated with copper: 14–15.6 g/cm³, thermal conductivity around 200 W/m·K and expansion of 8–10 ppm/K, tuned to match alumina and semiconductor packages. Tungsten-rhenium (W-25Re) is the ductile tungsten, formable at room temperature. The doped TIG electrodes — EWLa-1 (WL15), EWTh-2 (WT20), EWZr-1 (WZ8) — and WVMA (Doped Non-Sag Tungsten) filament wire carry an oxide or potassium dopant that controls arc starting or high-temperature creep.
Which grade of specialty tungsten should I use?
W70Cu30 for EDM electrodes and resistance-welding electrodes that must not erode, and for high-voltage arcing contacts; W80Cu20 when the heat-spreader or package base needs a lower expansion match and stiffness matters more than conductivity. W-25Re for thermocouple legs, ductile filaments and high-temperature springs that pure tungsten would snap. EWLa-1 (WL15) is the general-purpose TIG electrode for AC and DC on steel, stainless, titanium and aluminum; EWZr-1 (WZ8) for AC aluminum and magnesium where a stable balled tip resists contamination; EWTh-2 (WT20) is the older DC electrode, mildly radioactive and being replaced by the lanthanated grade. WVMA (Doped Non-Sag Tungsten) is lamp and heater filament wire.
Which grade of specialty tungsten is the strongest?
WVMA (Doped Non-Sag Tungsten) has the highest yield strength in the series at 1,900 MPa; W-25Re follows at 1,850 MPa. Values are for each grade's default condition.
Which grade of specialty tungsten is easiest to machine?
W70Cu30 (machinability fair, 35/100), then W80Cu20 (30/100).
W70Cu30 or W80Cu20?
More copper means more conductivity and easier machining; more tungsten means lower expansion, higher stiffness and better arc-erosion resistance. W70Cu30 is the EDM-electrode and resistance-welding standard and the better conductor; W80Cu20 is the heat-spreader and package-base grade because its 8–9 ppm/K expansion sits closer to alumina and gallium arsenide. For arcing contacts either works; the higher tungsten grade lasts longer, the higher copper grade runs cooler.
Which TIG electrode replaces thoriated?
EWLa-1 (WL15) for almost everything. Lanthanated tungsten starts as easily as thoriated, carries the same current, runs on both AC and DC and holds a point longer, with no radioactive dust when grinding. EWZr-1 (WZ8) is the specialist for AC aluminum and magnesium where the tip is meant to ball. Keep EWTh-2 (WT20) only where a procedure qualification names it.