Palladium Alloys
Palladium is the light platinum-group metal: 12.0 g/cm³ against 21.45 for platinum, melting at 1,555 °C, white, hypoallergenic and inert to most acids and to body fluid. Pure palladium is soft (about 40 HV, 190 MPa tensile annealed) and has one property no other metal shares to the same degree — it absorbs up to 900 times its own volume of hydrogen, which makes Pd-Ag and Pd-Cu membranes the standard for hydrogen purification. It oxidizes slightly between 400 and 800 °C in air, unlike platinum. Pd950 is the jewelry alloy; Pd-Ag and Pd-Cu are the contact, dental and membrane alloys.
Popular palladium grades
Compare in the explorer| Grade | Yield, MPa | Tensile, MPa | Density, g/cm³ | Machinability | Weldability | Best for |
|---|---|---|---|---|---|---|
| Pd950 | 130 | 290 | 12 | Fair | Excellent | Light, white, hypoallergenic jewelry |
| Pure Pd | 55 | 180 | 12.02 | Fair | Excellent | Anodes, catalyst substrates, targets |
| Pd99.9 | 55 | 180 | 12.02 | Poor | Very good | High-purity capacitor and electronic palladium |
| Pd60Ag40 | 180 | 415 | 11.35 | Fair | Very good | Relay contacts, wipers and dental frameworks |
| PdCu | 240 | 500 | 10.4 | Poor | Good | Sulfur-tolerant hydrogen membranes, hard contacts |
| PdNi | 250 | 550 | 11.3 | Poor | Good | Connector plating as a gold substitute |
| PdRu5 | 210 | 450 | 12.05 | Poor | Very good | Ruthenium-hardened 950 jewelry alloy |
Choose palladium for
White jewelry that must be light, hypoallergenic and white without plating; dental crown and bridge frameworks bonded to porcelain; hydrogen purifiers and sensors; relay, wiper and slip-ring contacts in sulfur-bearing or low-current service; multilayer-capacitor and thick-film electrodes; connector plating as a gold substitute; and brazed joints in vacuum tubes and high-temperature assemblies.
Look elsewhere when
The part runs hot in air between 400 and 800 °C, where palladium oxidizes and Pt99.95 or Pt90Rh10 stay clean; it lives in a vacuum system with hydrogen present, which palladium absorbs and swells on; the jewelry buyer wants the density and heft of Pt950; the contact carries high current, where Silver 999 or 90Ag-10SnO2 conduct better; or a gold flash over nickel does the connector job at lower cost than a PdNi layer.
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Palladium by application
- Jewelry
- Pd950 in the PdRu5 version for cast and fabricated rings and settings — about 100 HV, white without plating, half the weight of platinum; Pd950/Pd500 for the two recognized hallmark finenesses.
- Contacts and connectors
- Pd60Ag40 and 60Pd-40Ag wire and inlay for relay contacts, slip rings and potentiometer wipers that must stay clean in sulfur-bearing air; PdNi plating under a thin gold flash on connectors; the ASTM contact-alloy grades ASTM B540, ASTM B563 and ASTM B685 for specified compositions.
- Hydrogen purification
- Pd-Ag membranes in the Pd60Ag40 family for ultra-pure hydrogen in semiconductor and laboratory generators; PdCu where the feed gas carries sulfur compounds that poison Pd-Ag.
- Dental and electronic
- Pd-Ag and Pd-Cu-Ga frameworks for porcelain-fused-to-metal crowns; Pd99.9 and Pure Pd powder and foil for multilayer-capacitor electrodes and thick-film conductors; AWS BVPd-1 for vacuum brazing of tube and sensor assemblies.
Working with palladium
- Machining
- Soft and gummy like platinum; PdRu5 and the Pd-Ag alloys cut best. Sharp polished carbide, high speed, light cuts, light oil and complete chip recovery — swarf is refined and the job reconciled by weight.
- Casting and forming
- Pd950 casts at about 1,600 °C under argon, since molten palladium absorbs gas and the ruthenium oxidizes; gas porosity is the common defect in air-cast pieces. The pure metal and Pd-Ag alloys roll, draw and deep-draw like copper; anneal at 800–900 °C in a protective atmosphere to avoid the oxide film.
- Joining
- Laser and TIG welding without filler give clean joints in Pd950 and Pd-Ag; hard soldering uses palladium- or platinum-bearing white solders so the seam stays white. Keep the metal away from hydrogen-containing flames and atmospheres when hot — it absorbs hydrogen and can blister on cooling.
- Finishing
- Polishes to a bright gray-white mirror that needs no rhodium; a light heat tint from 400–800 °C exposure is removed by polishing or by a brief anneal above 800 °C. Hallmarking and assay on request.
Other precious metal series
Palladium Alloys — frequently asked
What is palladium?
Palladium is the light platinum-group metal: 12.0 g/cm³ against 21.45 for platinum, melting at 1,555 °C, white, hypoallergenic and inert to most acids and to body fluid. Pure palladium is soft (about 40 HV, 190 MPa tensile annealed) and has one property no other metal shares to the same degree — it absorbs up to 900 times its own volume of hydrogen, which makes Pd-Ag and Pd-Cu membranes the standard for hydrogen purification. It oxidizes slightly between 400 and 800 °C in air, unlike platinum. Pd950 is the jewelry alloy; Pd-Ag and Pd-Cu are the contact, dental and membrane alloys.
Which grade of palladium should I use?
Pd950 for jewelry: 95 % palladium hardened with ruthenium (PdRu5) or gallium, white through its full thickness, half the weight of Pt950 and needing no rhodium plating. Pure Pd and Pd99.9 for plating anodes, catalyst substrates, multilayer-capacitor electrodes and sputter targets. Pd60Ag40 (also written 60Pd-40Ag) for relay contacts, potentiometer wipers and slip rings where a silver alloy would tarnish, and as the porcelain-bonding dental framework alloy; the Pd-25Ag composition is the hydrogen-membrane standard. PdCu for membranes that must tolerate sulfur in the gas and for hard contact alloys; PdNi for connector plating as a gold substitute or underlayer; AWS BVPd-1 is the vacuum-grade palladium-nickel brazing filler for high-temperature joints. Pd950/Pd500 covers the two hallmark finenesses recognized for palladium jewelry.
Which grade of palladium is the strongest?
AWS BVPd-1 has the highest yield strength in the series at 380 MPa; B563 follows at 250 MPa. Values are for each grade's default condition.
Which grade of palladium is easiest to machine?
Pd950/Pd500 (machinability fair, 45/100), then B563 (40/100).
Pd950 or Pt950 for a ring?
Both are 95 % pure, white without plating, hypoallergenic and take the same finishes. Pd950 weighs half as much (12 against 21.45 g/cm³), so a heavy design is comfortable and uses less metal, and it is usually the lower-cost choice. Pt950 has the heft and the market recognition, is somewhat harder in the ruthenium alloy, and its casting and soldering are better understood by most workshops — palladium must be cast under argon to avoid porosity. For a plain band the difference is weight and price; for a fine setting many jewelers still prefer platinum.
Why does palladium absorb hydrogen, and does it matter?
Hydrogen dissociates on the palladium surface and its atoms sit in the metal lattice at very high density — up to 900 volumes per volume — and pass through it, which is the principle of every Pd-Ag purifier and many hydrogen sensors. The same property is a hazard elsewhere: palladium heated in a hydrogen-rich flame or furnace swells, embrittles and can blister on cooling, and palladium parts in vacuum systems that see hydrogen change dimension. Anneal and braze palladium in argon or nitrogen, not in forming gas.