Home · Materials · C145 Tellurium Copper
Copper Alloy

C145 Tellurium Copper

C145 tellurium copper adds roughly 0.5% tellurium to high-purity copper, breaking up chips so the alloy machines fast while keeping about 90-95% of pure copper's conductivity. At 355 W/m·K thermal and 70 HRB, it gives you a near-free-machining conductor that pure C110 cannot match on the lathe.

How C145 Tellurium Copper machines

Rated 4.5/5, the highest of any high-conductivity copper. The tellurium phase fragments chips that would otherwise tear and smear like pure copper, so it runs at high feeds on screw machines with good surface finish and long tool life, approaching free-cutting brass behavior.

Manufacturing & processing

Supplied for CNC turning and milling, extrusion, and forging. It is not a casting alloy here. Soldering, brazing, and resistance welding are routine for electrical assembly. It does not age-harden, so strength comes from cold work, not heat treatment.

Typical applications

Used where a part must both carry current and be machined in volume: electrical contacts, connector pins, terminals, welding-tip holders, switch components, and conductive fasteners. The 355 W/m·K conductivity also suits heat-sink hardware and resistance-welding electrodes that must shed heat.

When to choose it

Choose C145 over C110 when conductivity-critical parts have screw-machine geometry and C110's gummy chips kill throughput. Choose it over C360 brass when you need true copper-level conductivity, not just machinability. Skip it if pure conductivity with no machining drives the part: plain C110 costs less.

Suitable surface finishes

Common finishes for C145 Tellurium Copper: nickel plating, chrome plating, electropolishing, brushed. Use the finish selector →

FAQ

How much conductivity does C145 lose versus pure copper?
Only a few percent. The small tellurium addition keeps electrical conductivity around 90-95% IACS and thermal conductivity near 355 W/m·K, versus roughly 391 for C110. You trade a slight conductivity dip for dramatically easier machining, which is usually worthwhile for machined conductors.
Can C145 be age-hardened like beryllium copper?
No. C145 is not a precipitation-hardening alloy. Its strength, around 250 MPa tensile and 70 HRB, comes from cold working. If you need spring temper or high yield in a copper, look to C172 beryllium copper or C510 phosphor bronze instead.
Is C145 a drop-in machining substitute for C110?
Often yes for machined conductors. It holds nearly the same conductivity but cuts at 4.5/5 machinability instead of C110's gummy 3/5, so cycle times and finish improve sharply. Confirm your conductivity spec allows the small drop and that tellurium is acceptable for the application.

Property values are typical/nominal for early guidance and vary by temper, grade, supplier and heat treatment. Confirm critical specs against a certified datasheet or with an mfgiq engineer.