AM Cuvalues describe: green-laser SLM Cu
Big science (accelerators, light sources, public fusion)
What it enables
Printed RF and SRF geometries impossible to machine or braze.
Status and pusher
Copper membranes leak-tested against UHV specs; niobium SLM under development at CERN. Pushed by CERN, GSI, and the AM industry.
Properties
The values below are candidate: compiled from the sources named, not yet individually validated.
Provisional provenance: Additive manufacturing vacuum qualification studies; CERN Accelerator School, vacuum and materials proceedings.
Wet cleaning
| Recipe | unresolved: internal channels cannot be verified clean; chemical polishing and abrasive flow machining are being trialled |
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| Forbidden | assuming an internal surface is clean because the external one is |
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| Limit | internal surface access: the open problem of the whole family |
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Vacuum and outgassing
| Outgassing, unbaked (10 h) | 5e-9 mbar·L/s/cm² |
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| Outgassing, baked | 5e-12 mbar·L/s/cm² |
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| Vapour pressure | negligible |
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Temperature
| Bake, assembled | 400 °C |
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| Vacuum degas | 600 °C |
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| Braze / H2 firing | 900 HIP °C |
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| Metallurgical limit | recrystallises from 200 °C |
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Thermal
| CTE | 17 ppm/K |
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| Thermal conductivity | 250–350, below wrought W/m·K |
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| Specific heat | 385 J/kg·K |
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| Emissivity | 0.1 as-built |
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| Melting / softening | 1085 °C |
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Mechanical
| Strength | 150–250 ys MPa |
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| Tensile | 250–350 MPa |
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| Elongation | 20–40 % |
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| Young's modulus | 110 GPa |
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| Hardness | 70–90 HV |
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| Density | 8.7–8.9 g/cm3 |
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Electrical and magnetic
| Relative permeability | ~1.0 |
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| Resistivity | 2.2 µΩ·cm |
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Engineering
| Corrosion | as wrought |
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| Joining | brazed |
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| Process notes | density and oxygen content decide usability |
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| Availability and cost | few qualified bureaux |
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Sources · 1
- Green laser AM copper for UHV accelerator components
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