Technical overview
Pure coppers are difficult to machine (CDA rates oxygen-free copper at 20 on the 100-point scale). Tellurium copper, C14500, adds 0.40–0.7% tellurium, raising the machinability rating to 85 while keeping 93% IACS conductivity.
That combination makes it a common choice for machined electrical connectors, switch parts, transistor bases, soldering tips and welding torch tips.
Grades & standards
Grades are distinct materials — properties and uses below apply to the named grade only.
C14500
Tellurium-Bearing Copper
Composition: Cu ≥ 99.90% (incl. Te + P + Ag), Te 0.40–0.7%, P 0.004–0.012%
- 93% IACS
- Machinability rating 85
- Resistance to thermal softening
Listed specifications: ASTM B301/B301M · ASTM B124/B124M · ASTM B283/B283M
Technical properties
| Property | Value | Applies to | Source |
|---|---|---|---|
| Electrical conductivity | 93% IACS | C14500 | Copper Development Association Inc. |
| Machinability rating | 85 | C14500 | Copper Development Association Inc. |
| Melting range | 1051–1080 °C | C14500 | Copper Development Association Inc. |
| Specific gravity | 8.94 | C14500 | Copper Development Association Inc. |
Typical or specified values for the named grade from the cited source. Actual values depend on temper, size and the producing mill — rely on the mill certificate for your lot.
Forms
Typical industry forms for this material. They are not a stock list — form, size and availability are confirmed per enquiry.
- Rod (round, hex)
- Bar
- Wire
- Forgings
Applications & industries
- Machined electrical connectors and terminals
- Switch and motor parts
- Soldering and welding torch tips
- Screw-machine products and forgings
Selection notes & limitations
- Conductivity is lower than OF/ETP copper (93% vs ≥ 100% IACS). If maximum conductivity matters more than machining, specify pure copper.
What to specify when requesting a quote
- 1Rod or bar size and the machining process (CNC turning, screw machine)
- 2Temper required
- 3Grade and the standard it must conform to (ASTM, EN, IS, UNS or your drawing)
- 4Form and dimensions — thickness or diameter, width, length and tolerances
- 5Approximate quantity, and whether the requirement is one-off or recurring
- 6Intended application, so the grade can be cross-checked before quoting
- 7Documents required — e.g. mill test certificate, chemical analysis, certificate of conformity
- 8Delivery city / site and the date you need material by
Documents buyers may request
Mill test certificate
e.g. EN 10204 type 3.1 inspection certificate, where the producing mill issues one
Chemical analysis report
heat / lot composition against the specified grade
Certificate of conformity
confirming the material meets the ordered standard
Heat / lot traceability
heat numbers marked on material and documents
Dimensional inspection report
for cut-to-size or machined material
Safety Data Sheet (SDS)
especially for lead, beryllium-, cadmium- or lead-bearing products
Which documents can be provided depends on the source mill and is confirmed with each quotation.
Frequently asked questions
Is "Terilium copper" the same as tellurium copper?
Yes. "Terilium" in our product list refers to tellurium copper, UNS C14500.
Sources & technical references
- C14500 — Tellurium-Bearing Copper (CDA alloy database) — Copper Development Association Inc. (CDA). Checked 2026-10-14.
