Nickel Aluminum 80/20 — 80% Ni, 20% Al — is the flame-spray shop's workhorse self-bonding bond coat. Cross-references: Oerlikon Metco 404NS (chemically clad powder), Metco 2101ZB, Metco 405A composite wire, TAFA 79B.

The magic is chemistry. During flame spray the aluminum core melts and chemically unites with its nickel shell in-flight, forming nickel aluminides (Ni₃Al, NiAl) in an exothermic reaction that drives droplet temperatures to ~2,400°C. That heat spike metallurgically wets the grit-blasted substrate — the coating micro-welds itself down. Metco's DSMTS-0029.5 publishes 20.7 MPa (3,000 psi) tensile bond; field suppliers document 9,000+ psi; peer-reviewed plasma-spray studies measure 51 MPa with fine cuts.

Why 80/20 instead of the 95/5 siblings (Metco 450NS, Amdry 956, Metco 8400)? More aluminum means a hotter, more complete exothermic reaction and stronger self-bonding — at the cost of service temperature. 80/20 tops out at 650°C (1,200°F); the 95/5 materials run to 800°C. Pick 80/20 when bond strength is the job, 95/5 when the temperature ceiling is.

At HTS we spray 80/20 NiAl by combustion powder Thermospray or APS — 3-6 mils under ceramic and carbide topcoats, 10-40 mils as standalone salvage build-up on worn shafts and journals. Microhardness 190-230 HV, CTE 12.6 × 10⁻⁶/K — a clean bridge between steel and ceramic. Decades of qualified service under PWA, GE, Rolls-Royce, and Snecma specs.

Technical data

Hardness: 190-230 HV0.3 microhardness (Oerlikon Metco DSMTS-0029.5 typical data for Metco 404NS/2101ZB); Knoop HK50 320-685; macrohardness HRB 75-81 (Rockwell B). Coatings are multi-phase lamellar — α-Al, γ-Ni, β-NiAl, γ′-Ni₃Al, Ni₂Al₃ intermetallics plus α-Al₂O₃/NiO inclusions — so micro-indent scatter is real.
Bond strength: 3,000 psi (20.7 MPa) per Oerlikon Metco DSMTS-0029.5 typical data (tensile, ASTM C633 style); field data from independent suppliers (Polymet PMET 884, Certilas SP 80/20) reports 9,000+ psi (62+ MPa) on properly grit-blasted steel. Peer-reviewed plasma-spray studies on Ni-20Al composite powders measured 40-51 MPa (5,800-7,440 psi) adhesive strength, climbing with smaller particle size and complete Ni/Al reaction. The self-bonding exothermic mechanism is the reason — the in-flight Ni+Al→NiAl reaction releases ΔH ≈ -118 kJ/mol, heating droplets locally to ~2,400°C and producing metallurgical wetting at the substrate interface.
Max service temp: 1,200°F (650°C) per Oerlikon Metco DSM-0271.6 and DSMTS-0029.5 for the 80/20 product family. The lower service ceiling (vs. 1,470°F / 800°C for 95/5 Ni-Al) is the trade-off for higher Al content and stronger exothermic bond — more free Al available to form aluminides means less dilute γ-Ni(Al) oxidation reserve at temperature.
Max service temp: 650°C oxidation-limited per OEM datasheet; 95/5 siblings (Metco 450NS, Amdry 956, Metco 480NS, Diamalloy 4008NS) run to 800°C because the lower Al content preserves more γ-Ni phase. Pick 80/20 for bond strength; pick 95/5 for high-temp service.
As-sprayed porosity: 4-7% typical APS (peer-reviewed: 4.4% fine-powder / 5.7% mid-powder / 6.4% coarse-powder at 25 kW arc power); combustion powder Thermospray typically 5-10%; coarser Metco 2101ZB produces greater as-sprayed surface roughness than Metco 404NS by design.
Typical thickness: 3-6 mils (75-150 µm) as a bond coat under ceramic topcoats (YSZ, alumina, chrome oxide) or thick metallic hardfacing overlays; 10-40 mils (250-1000 µm) as a standalone salvage and dimensional-restoration build-up on worn or mismachined carbon steel and corrosion-resistant substrates.
Density: ~6.9 g/cm³ as-deposited coating (Oerlikon Metco DSMTS-0029.5); powder apparent density 3.0 g/cm³ (Metco 404NS) / 3.2 g/cm³ (Metco 2101ZB).

Where it earns its keep

Highest bond strength of any flame-spray bond-coat powder — the 20 wt% Al creates a more vigorous exothermic Ni+Al→NiAl reaction than 95/5 Ni-Al siblings, which is the mechanism behind self-bonding on grit-blasted steel
Self-bonding — requires minimal surface prep on difficult substrates (thin sheet, hard hardened steel, complex geometry) where full grit-blast profile is impractical
Decades of qualified aerospace flight service under proprietary OEM specs (PWA 1321, GE B50TF33 Cl A, Rolls-Royce MSRR 9507/4, Snecma DMR 33.010, Honeywell EMS 57746, MTU MTS 1073)
Sprays on both APS and combustion powder Thermospray — field-practical with equipment most thermal-spray shops already have (no HVOF required)
Excellent CTE bridge between steel substrates (~12 × 10⁻⁶/K) and ceramic topcoats (~8-10 × 10⁻⁶/K) — measured CTE 12.6 × 10⁻⁶/K per Oerlikon Metco DSMTS-0029.5
Dense (~6.9 g/cm³), moderately hard (190-230 HV), reasonably tough — also works as a standalone salvage and dimensional-restoration coating up to 10-40 mils
Global stock availability (Metco 404NS order no. 1000060, 5 lb plastic jars) — the most widely specified Ni-Al bond coat powder in the Oerlikon Metco catalog

Where it doesn't

Service-temperature ceiling of 650°C (1,200°F) is 150°C lower than 95/5 Ni-Al siblings (Metco 450NS, Amdry 956, Metco 8400 at 800°C / 1,470°F) — the trade-off for higher bond strength. Do not specify 80/20 for hot-section duty above 650°C; choose 95/5, Amdry 960 / Metco 443NS (Al-clad NiCr), Amdry 962 (NiCrAlY), or Amdry 995 (CoNiCrAlY) instead.
This is a BOND COAT, intermediate layer, or mild-corrosion overlay — NOT a primary wear coating. For abrasion, erosion, or sliding wear, specify tungsten carbide, chromium carbide, or chrome-oxide topcoats over this bond layer.
Not recommended for HVOF — the shorter particle dwell time suppresses the Ni/Al exothermic reaction that defines the self-bonding mechanism. Use APS or combustion powder Thermospray; for HVOF applications use Diamalloy 4008NS (pre-alloyed 95/5 fine-cut).
Peer-reviewed studies show particle size controls reaction completeness — powders <50 µm complete the Ni+Al reaction in-flight; >50 µm powders show unreacted Al residue and degraded coating performance. Feedstock cut matters.
Store powder and composite wire at ≤60% humidity, 15-25°C. Wire exposed to severe moisture should be redried at 150°C × 6 h (up to 200°C × 12 h), no more than 6 redries.
As-sprayed surface is rough; grinding is the recommended finishing method per OEM datasheet. If machinable build-up is the goal, consider Metco 452 / Metco 453 which have better as-sprayed machinability.

Sources

Data points on this page draw on the following published references. Nothing here replaces a material-specific review by our process engineers — but it's the working starting point.

Oerlikon Metco DSM-0271.6 — Nickel-Aluminum Materials (Master Product Data Sheet, 2025)
“Metco 404NS and Metco 2101ZB: 80 wt% Ni / 20 wt% Al, chemically clad spheroidal powder, apparent density 3.0-3.2 g/cm³, -90 +53 µm (404NS) and -125 +45 µm (2101ZB). Exothermic self-bonding. Recommended for APS and combustion powder Thermospray. Maximum service temperature 650°C (1,200°F). Metco 405A composite cored wire (3.2 mm, 80Ni/20Al) sprayed by combustion wire spray. Metco 404NS and 2101ZB produce a vigorous exothermic reaction during spraying for optimized bond strength. Used as bond coat under ceramics and abradables, and for salvage and restoration on steel and nickel-based substrates.”
Oerlikon Metco DSMTS-0029.5 — 80% Nickel / 20% Aluminum Chemically Clad Powders (Metco 404NS, Metco 2101ZB, 2017)
“Coating density ~6.9 g/cm³. Deposit efficiency 50-65%. Macrohardness HRB 75-81. Microhardness HV0.3 190-230, HK50 320-685. Bond strength 20.7 MPa (3,000 psi). Coefficient of thermal expansion 12.6 × 10⁻⁶/K (27-538°C). Electrical resistivity 220 µΩ·cm. Recommended process: APS or combustion powder Thermospray. During spray the nickel and aluminum chemically unite to form nickel-aluminides in an exothermic reaction that imparts additional heat to the molten particles. Used as bond coat to improve adherence of subsequently sprayed top-coat deposits, as an intermediate coating to mitigate CTE mismatch, and as an oxidation-resistant bond coat for service up to 650°C.”
Pang et al. — Effect of Powder Particle Size and Spray Parameters on the Ni/Al Reaction During Plasma Spraying of Ni-Al Composite Powders (Journal of Thermal Spray Technology, 2021 / PMC peer-reviewed)
“Fine Ni-Al composite powders (<50 µm) produce coatings with 4.4 ± 0.2% porosity and 51.3 MPa adhesive strength when fully reacted; coarser cuts drop to 40.2 MPa and 6.4% porosity. Particle size is the dominant factor controlling the exothermic reaction for NiAl intermetallic formation; smaller powders enable complete reaction and drive droplet surface temperatures to ~2,400°C, which is what produces the self-bonding effect. Coatings consist of Ni₃Al, NiAl, residual Al, NiO, and Al₂O₃ phases.”
Matikainen, Hasan, Vuoristo — Ni-Al and NiO-Al Composite Coatings by Combustion-Assisted Flame Spraying (Coatings, MDPI, 2014, peer-reviewed)
“Combustion-assisted flame spraying (CAFSY) of Ni-Al composite feedstock synthesizes NiAl intermetallic phases in-flight during oxy-acetylene flame spraying; the Gibbs free energy of aluminide formation is negative and the reaction is exothermic. Ni + Al → NiAl has a stoichiometric melting point of 1,640°C, and the exothermic reaction releases sufficient heat to melt and consolidate the depositing splats. Coatings consist of various fractions of Ni, Al, Al₃Ni, Ni₃Al, NiAl, NiO, and spinel NiAl₂O₄. Used to deposit self-bonding bond coats under ceramic top coats.”
Polymet PMET 884 BONDRITE® — Ni 20Al Thermal Spray Wire (commercial 80/20 NiAl equivalent to TAFA 79B / Metco 405)
“Rockwell hardness 60-80 B. Bond strengths in excess of 9,000 psi can be achieved on grit-blasted surfaces. Self-bonding capability, high-temperature oxidation resistance, excellent resistance to impact and bending. Widely used as a bond coat for subsequent thermal spray topcoats. Available in 1/16" and 1/8" (1.6 mm and 3.2 mm) wire diameters for combustion wire spray and electric arc wire spray.”
Certilas SP 80/20 NiAl — 80% Ni / 20% Al Thermal Spray Wire (EN ISO 14919 Classification 6.6)
“As-welded hardness 75 HB (Brinell). Bond strengths in excess of 9,000 psi achievable on grit-blasted surfaces. Cored wire supports both arc spray and flame spray processes. Used as bond coating for thermal spray layers and for restoring aircraft engine dimensions through buildup operations. Good resistance to high-temperature oxidation and abrasion, excellent resistance to impact and bending. Can be machined and ground to a 5 micro-inch finish.”
Sampath et al. — Reactive Spraying of Nickel-Aluminide Coatings (Journal of Thermal Spray Technology, peer-reviewed)
“Reactive spraying of nickel and aluminum feedstock yields coatings consisting of Ni, Al, Ni₃Al, NiAl₃, Ni₅Al₃, NiAl, and Al₂O₃ depending on spray conditions. The formation of nickel aluminide phases in plasma-spray depositions is attributed to the exothermic reaction between aluminum and nickel splats in-flight and during impact. This reaction is what provides the self-bonding behavior characteristic of 80/20 Ni-Al bond coats.”
Gordon England Surface Engineering Forum — Ni-Al 80/20 vs 95/5 Flame Spray Wire (industry practitioner discussion)
“OEM bond strength data: Ni-95Al-5 = 9,750 psi, Ni-80Al-20 = 8,750 psi on grit-blasted steel. Historical industry observation: the 80/20 composition can dominate the 95/5 in the gas flame-spray process because the higher Al content drives a more vigorous exothermic reaction, but arc spray has largely replaced flame spray for general industrial bond coats. Both compositions remain specified for self-bonding applications; choice between them is a trade between bond strength (80/20) and service temperature (95/5 runs to 800°C vs. 650°C for 80/20).”

Material data on this page is provided as a general reference and can vary by lot, substrate, and application. Contact HTS to confirm the right material and specification for your specific part.

Nickel Aluminum

Technical data

Where it earns its keep

Where it doesn't

Typical applications

Industries

Substrates

Sources

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