GRCop-84
metalcopper alloy — dispersion/precipitation strengthened
Cu-8Cr-4NbGRCop84NASA GRCop-84Glenn Research Copper-84
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
| Property | LPBF as-built (XY) | LPBF aged 500°C/4h (XY) |
|---|---|---|
| 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 | — |
Values shown as min–max where a spread is reported, otherwise as typical ± unit. Ranges reflect inter-source variation, not single-sample scatter. All values are for AM-processed specimens unless noted.
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)
Industries
aerospacedefenceenergy
Compatible AM processes (1)
Other metal materials
Ti-6Al-4V Grade 5titanium alloy — alpha-betaTi-6Al-4V ELI (Grade 23)titanium alloy — alpha-beta (extra low interstitial)CP-Titanium Grade 2commercially pure titanium — alphaCP-Ti Grade 4titanium — commercially pure alphaTi-6Al-2Sn-4Zr-2Motitanium alloy — near-alpha316L Stainless Steelaustenitic stainless steel304L Stainless Steelaustenitic stainless steel17-4PH Stainless Steelmartensitic precipitation-hardening stainless steel15-5 PH Stainless Steelmartensitic precipitation-hardened stainless steel420 Stainless Steelmartensitic stainless steelAlSi10Mgaluminium-silicon alloy (cast grade adapted for AM)AlSi7Mg Aluminium Alloyhypoeutectic Al-Si-Mg precipitation-hardenable aluminium alloyScalmalloy®aluminium alloy — Al-Mg-Sc-ZrAlSi12aluminium — hypoeutectic/eutectic Al-SiInconel 718nickel superalloy — precipitation-hardenedInconel 625nickel superalloy — solid-solution-strengthenedInconel 939nickel superalloy — γ'-precipitation-hardened (high Al+Ti)Hastelloy® Xnickel superalloy — solid-solution strengthenedWaspaloy®nickel superalloy — γ'-precipitation-hardenedHaynes 282nickel superalloy — γ' precipitation-hardenedCoCrMocobalt-chromium alloy (biomedical and aerospace grade)Maraging Steel MS1 (18Ni-300)maraging steel (ultra-high-strength, precipitation-hardened)M300 Tool Steel (18Ni-300 Maraging Steel)maraging steel — tooling grade (ultra-high-strength, precipitation-hardened)H13 Tool Steelchromium-molybdenum hot-work tool steelCuCrZrcopper alloy — precipitation-hardenedCu-CP (Commercially Pure Copper)copper alloy — commercially pureCuSn10 (Bronze)copper alloy — tin bronzeInvar 36iron-nickel low-expansion alloyNiTi / Nitinolnickel-titanium shape-memory alloy
Related calculators
LPBF Porosity PredictorPredict lack-of-fusion and keyhole porosity from laser parameters. Maps VED and normalised enthalpy to relative density and flags dangerous regimes.Powder Characterisation TrackerScore a powder batch against key qualification metrics — particle size distribution, flowability, apparent/tap density, moisture, and oxygen content.Surface Treatment SelectorRank post-print surface treatments (shot peening, electropolishing, tumbling, PVD, and more) against Ra target, material, fatigue criticality, and corrosion requirements.NDT SelectorSelect the right non-destructive testing method for your AM part. Inputs: material class, defect focus, geometry, production volume, and criticality. Ranked scorecard across CT, X-ray, UT, FPI, MPI, eddy current, and visual inspection with detection limits and standard references.Laser ParamsDerive LPBF process parameters from target VED and melt-pool stability constraints. Power–speed–hatch–layer sensitivity matrix with keyholing and balling risk zones.Melt PoolLPBF / DED melt pool depth, width, and cooling rate from the Rosenthal moving heat source solution. Absorptivity, thermal diffusivity, and solidification velocity.
Last reviewed: 2026-05-13 · v1 · Sources: nasa-grcop84-2020, gradl-2019-grcop-am, cooper-2021-cu-lpbf
Unlock the full property data — sign up free
Free account · no credit card · no marketing. Sign up to unlock the full library: 26 articles, 45 materials, 10 processes, 43 papers and more.