GRCop-84

metal

copper alloy — dispersion/precipitation strengthened

Cu-8Cr-4NbGRCop84NASA GRCop-84Glenn Research Copper-84

Density

8.83 g/cm³

YS (LPBF as-built (XY))

230–320 MPa

UTS (LPBF as-built (XY))

260–350 MPa

Elongation (LPBF as-built (XY))

15.0–35.0 %

Thermal conductivity

305.0–340.0 W/m·K

Max service temp

700 °C

Composition — NASA GRC internal specification — Cu-8Cr-4Nb (at%)

Element	Min %	Max %	Notes
Cu	—	—	balance — pure copper matrix provides thermal conductivity
Cr	—	—	8 at% (~5.0 wt%); forms Cr₂Nb Laves phase for high-temperature strength
Nb	—	—	4 at% (~5.8 wt%); key Laves-phase former; Cr₂Nb pins dislocations at 700°C
O	—	0.050	Oxygen contamination degrades thermal conductivity and promotes porosity; strict atmosphere control required

Mechanical & thermal properties — 2 conditions

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Engineering considerations

Green laser selection: If budget allows, specify a green-laser LPBF system (e.g., Trumpf TruPrint with green module, or Aconity dedicated green system). Copper absorptivity at 532 nm is ~40% vs ~5% at 1064 nm — dramatically more stable melt pool and lower porosity.
High-power IR approach: If green laser is unavailable, use IR power ≥400 W with scan speeds <500 mm/s to achieve sufficient energy deposition. Expect higher spatter and porosity; require systematic parameter development and CT verification.
Atmosphere control: Use high-purity argon (<10 ppm O₂, <10 ppm H₂O). Even minor oxidation forms Cu₂O inclusions that reduce thermal conductivity and weaken grain boundaries. Do not reuse powder without oxygen content verification.
Post-processing: Aging at 500°C/4h in vacuum or argon furnace before service. Do not anneal — full anneal removes precipitates and reduces elevated-temperature strength.
Thermal management design: Wall thickness in cooled chambers limited by channel geometry and pressure requirements, not thermal resistance. GRCop-84's high conductivity allows thinner walls; verify structural integrity with LPBF-specific material data, not handbook wrought copper data.
Inspection: Use helium leak testing for pressure channels (critical for combustion chambers). CT scanning to detect subsurface porosity clusters before pressure testing.
Powder storage: Copper powder is less pyrophoric than Ti or Al powders but must still be stored in sealed, dry containers. Moisture absorption increases O content in the melt.

Advantages

Unique combination of high thermal conductivity (~323 W/m·K) and elevated-temperature strength — no other AM metal offers both
Retains ~70% UTS at 700°C; standard copper alloys lose strength above 200°C
Cr₂Nb Laves phase is thermally stable — does not over-age or dissolve below 900°C
LPBF enables complex internal channel geometries (conformal cooling) impossible in conventional manufacturing
Near-pure-copper thermal conductivity allows thinner wall sections than CuCrZr for equivalent cooling
NASA-proven material heritage in multiple rocket engine programmes (SLS RS-25, Vulcan BE-4 development)

Limitations

Requires green laser (515–532 nm) for consistent LPBF processing; green laser LPBF systems are significantly more expensive than standard IR systems
High-power IR fibre lasers can process GRCop-84 but require very specific parameters and show higher porosity and spatter vs green laser
Powder is 10–20× more expensive than 316L stainless; cost-justify strictly on application requirements
Oxidation risk during build — strict atmosphere control (<50 ppm O₂) mandatory; surface oxidation degrades thermal conductivity
No widely adopted AM-specific material standard; qualification must follow OEM/NASA-internal specifications
Limited supplier base for GRCop-84 powder; Elementum 3D is the primary commercial supplier
Post-processing (machining) requires appropriate tooling due to copper's gummy cutting behaviour

Typical applications

Regeneratively-cooled rocket combustion chamber liners (inner wall)Rocket engine nozzle throats and nozzle extensionsThrust chamber injector faceplatesCryogenic rocket engine turbopump hot-section componentsHigh-heat-flux heat exchangers in propulsion test standsPlasma-facing components for fusion research (experimental)

GRCop-84

Composition — NASA GRC internal specification — Cu-8Cr-4Nb (at%)

Mechanical & thermal properties — 2 conditions

Engineering considerations

Advantages

Limitations

Typical applications

Industries

Compatible AM processes (1)

Other metal materials

Related calculators

Related guides

Yield strength (0.2%)	230–320 MPa	300–380 MPa
Ultimate tensile strength	260–350 MPa	340–420 MPa
Elongation at break	15.0–35.0 %	12.0–28.0 %
Density	8.83 g/cm³	—
Thermal conductivity	305.0–340.0 W/m·K	300.0–330.0 W/m·K
Max service temperature	700 °C	—