Nickel aluminide — nominal 95% Ni / 5% Al — is the universal bond coat of the thermal-spray trade. Oerlikon Metco's family: Amdry 956, Metco 450NS, 450P, 480NS, Diamalloy 4008NS (Ni + 4.0-5.5 wt% Al, DSMTS-0043.7). It goes down first under almost every ceramic, carbide, hardfacing, or abradable topcoat HTS sprays. The reason is a chemistry trick: aluminum-clad nickel particles hit the flame, aluminum melts, and the Ni+Al → NiAl reaction releases ~118 kJ/mol. Peer-reviewed work measures particles reaching ~2,400°C in flight. The superheated droplet hits the substrate, locally melts surface asperities, and forms a metallurgical + diffusion bond on top of the mechanical anchor. Self-bonding.

That matters when grit-blast profile alone is not enough — heat-treated parts, finish-machined surfaces, cast iron, smooth substrates where aggressive blasting would distort geometry. Oerlikon's minimum bond strength is 3,000 psi (20.7 MPa) on ground carbon steel for Amdry 956 / 450NS / 450P; Metco 480NS hits 10,000 psi (68.9 MPa); HVOF Diamalloy 4008NS 9,000 psi (62.0 MPa). Hardness ~200-300 HV. Porosity <5% APS, <3% HVOF. Service to 800°C / 1,470°F. Bond-coat thickness 3-8 mils. Qualified under SAE AMS 5739 and dozens of aerospace OEM specs.

Steel, nickel-base, cast iron, or already-machined part needing a hardfacing, ceramic, carbide, or abradable topcoat? Send us the stack-up — we will spec the layer under it.

Technical data

Hardness: ~200-300 HV typical as-sprayed for fully reacted 95/5 deposits — research on plasma-sprayed 95/5 Ni-Al reports NiAl phase microhardness around 250 HV 0.04, with independent work on plasma-sprayed Ni-Al composite coatings measuring 476 HV on unheated substrates and 493 HV on heated substrates depending on reaction completion and aluminum content.
Bond strength: 3,000 psi (20.7 MPa) minimum per Oerlikon Metco DSMTS-0043.7 on ground low-carbon steel for Amdry 956, Metco 450NS, and Metco 450P; fully alloyed Metco 480NS reaches 10,000 psi (68.9 MPa); HVOF Diamalloy 4008NS reaches 9,000 psi (62.0 MPa). Independent plasma-spray research on optimized 95/5 Ni-Al particle size (30-50 µm) measured 51.3 MPa (~7,440 psi) adhesive strength when the exothermic reaction completes fully. Bond strength is the whole reason this coating exists — and it climbs well above what a mechanical bond alone can deliver on a grit-blasted steel coupon.
Max service temp: 1,470°F (800°C) per Oerlikon Metco DSMTS-0043.7 for the 95/5 NiAl family (Amdry 956, Metco 450NS, Metco 480NS, Diamalloy 4008NS). Nickel-aluminum coatings retain good oxidation resistance up to this limit depending on the application environment. Note: the related 80/20 NiAl bond coats (Metco 404NS, Metco 2101ZB, Metco 447NS) carry a lower 1,200°F (650°C) service limit.
Max service temp: 800°C (95/5 family) / 650°C (80/20 family)
As-sprayed porosity: <5 vol% per Oerlikon Metco DSMTS-0043.7 for APS / combustion-powder deposits (Amdry 956, Metco 450NS, Metco 450P, Metco 480NS); <3 vol% for HVOF Diamalloy 4008NS. Peer-reviewed plasma-spray research on 95/5 Ni-Al reports 4-7% porosity depending on particle size and parameter window; coarser particles and incomplete exothermic reaction push porosity toward the top of that band.
Typical thickness: 3-8 mils (75-200 µm) as bond coat under a thermal-sprayed topcoat (hardfacing, ceramic, abradable, or corrosion overlay) — thin enough that the bond coat does not dominate the stack, thick enough to fully develop the diffusion-reaction zone. 10-25 mils (250-635 µm) as a standalone build-up and restoration layer. 1-3 mils (25-75 µm) as a thin tie-coat where only the substrate-side metallurgical anchor is needed.
Density: 7.2-7.4 g/cc deposit (Oerlikon Metco DSMTS-0043.7 for Amdry 956, 450NS, 450P, 480NS, and Diamalloy 4008NS). Apparent powder density 3.5-4.5 g/cc (mechanically clad or gas atomized).

Where it earns its keep

Self-bonding via exothermic Ni+Al → NiAl reaction during spray — the hallmark property. Aluminum melts, reacts with the nickel core, releases ~118 kJ/mol, drives particle temperature to ~2,400°C, and produces a metallurgical + diffusion bond that clears the 3,000-10,000 psi band on a coupon test
Works on substrates where traditional grit-blast anchor profile cannot be fully developed — heat-treated parts, finish-machined surfaces, cast iron, and situations where aggressive blasting would distort or contaminate the part
Universal compatibility with downstream topcoats — ceramic, carbide, hardfacing, abradable. The bond coat of first resort across the thermal-spray trade
Service temperature to 800°C (1,470°F) carries the bond coat through most turbine, furnace, and hot-gas-path applications without hitting its ceiling
Deposits at 3-8 mils thickness without dominating the total coating stack — thin enough to key into the topcoat, thick enough to fully develop the reaction zone
Applied by atmospheric plasma spray, combustion-powder Thermospray, and HVOF — every major powder process in the shop. Wire variants (Metco 405A, Metco 8400) extend the family to arc and flame-wire processes
Qualified under dozens of aerospace OEM specifications (Pratt & Whitney PWA, GE B50, Rolls-Royce MSRR, Honeywell EMS, SAE AMS 5739) — the regulatory paperwork is already done
Moderately priced relative to MCrAlY and cobalt-base bond coats — the cost-effective choice below 800°C
Dense (<5% porosity APS, <3% HVOF) and well-adhered from the gun, no fuse cycle required

Where it doesn't

Service temperature capped at 800°C (1,470°F) for the 95/5 family — above that, specify MCrAlY (Amdry 962, Metco 461NS) or aluminide diffusion coatings instead
Not a wear coating — pick this as a bond coat or restoration build-up, not as the service surface against abrasion or sliding load. Stack a hardfacing or carbide topcoat on it when wear is the duty
Exothermic reaction completion is particle-size and parameter-dependent — peer-reviewed work shows particles above 50 µm may not fully react, which reduces bond strength and raises oxide content. Stay with qualified Oerlikon Metco particle cuts (-90 +45 µm for Amdry 956 / 450NS; -45 +11 µm for Diamalloy 4008NS HVOF) rather than improvising
Deposits are not easily machined — grind-finish is standard on Amdry 956, Metco 450NS, Metco 480NS, and Diamalloy 4008NS. Metco 450P is the premium grade specifically designed for better machinability when grinding is undesirable
Moisture sensitivity — Oerlikon DSMTS-0043.7 specifies storage in dry conditions and recommends drying-oven storage for opened containers. Moisture pickup degrades spray behavior
For better high-temperature oxidation and hot-corrosion resistance above 800°C, step up to the NiCrAl family (Amdry 960, Metco 443NS, Metco 461NS) or NiCrAlY / CoNiCrAlY bond coats
For maximum exothermic vigor and bond strength at lower service temperature (<650°C), the 80/20 NiAl variants (Metco 404NS, Metco 2101ZB, Metco 405A wire) may be the better choice — higher aluminum content drives a more energetic reaction

Which process, when?

Atmospheric plasma spray (APS) is the canonical bond-coat route for Amdry 956, Metco 450NS, and Metco 450P — qualified under most aerospace OEM specs, lays down 3-8 mil bond coats with <5% porosity and a 450-600 µin Ra finish that mechanically keys into whatever topcoat stacks on next. Combustion-powder Thermospray is the lower-cost alternative for general-industrial bond-coat work where aerospace paperwork is not the driver — same powders, same reaction, lower plant investment. HVOF with Diamalloy 4008NS produces the densest (<3% porosity), smoothest (250-350 µin Ra) bond coat and is recommended where the topcoat is itself HVOF carbide or where the total stack must stay thin. Wire arc and flame-wire using Metco 405A, Metco 8400, Metco 8405, or Metco 8447 extend the family to twin-wire and combustion-wire processes for field work, large parts, and restoration jobs where powder-spray logistics are impractical. Pick APS for the default bond coat under ceramic or hardfacing; pick HVOF Diamalloy 4008NS when the topcoat is HVOF carbide; pick wire when the part is too big to gantry-spray with powder.

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 (2025)
“Portfolio of nickel-aluminum thermal-spray materials used as general-purpose coatings for restoration and as bond coats for OEM-specified and general-industrial applications under ceramic and abradable topcoats. Oxidation resistance up to 800°C (1,470°F). Exothermic materials (Amdry 956, Metco 450NS, Metco 404NS, Metco 2101ZB, Metco 447NS, Metco 8405, Metco 405A, Metco 8447) exhibit an exothermic reaction during spray processing and are considered self-bonding to metal alloy substrates — typically steel alloys. The exothermic reaction is enabled by the presence of an aluminum or aluminum-based mechanical or chemical cladding on nickel powder core for powder products, or an aluminum sheath filled with nickel powder for wires. Amdry 956 and Metco 450NS are very popular choices for low-temperature bond coats and general salvage and restoration on steel and nickel-based substrates when sprayed with atmospheric plasma spray or combustion powder spray. Metco 404NS and Metco 2101ZB produce a vigorous exothermic reaction during spraying for optimized bond strength.”
Oerlikon Metco DSMTS-0043.7 — Nickel – 5% Aluminum Thermal Spray Powders
“Product data sheet covering Amdry 956, Metco 450NS, Metco 450P, Metco 480NS, and Diamalloy 4008NS. Chemistry Ni + 4.0-5.5% Al (95/5). Apparent density 3.5-4.5 g/cc; deposit density 7.2-7.4 g/cc. Macrohardness 65-80 HRB (65-75 HRB for 450P; 25 HRC for Diamalloy 4008NS HVOF). Typical porosity <5 vol% APS/CPS, <3 vol% HVOF. Maximum service temperature 800°C (1,470°F) for the whole 95/5 family. Bond strength minimum 20.7 MPa (3,000 psi) for Amdry 956, Metco 450NS, Metco 450P; 68.9 MPa (10,000 psi) for Metco 480NS; 62.0 MPa (9,000 psi) for Diamalloy 4008NS HVOF (ground low-carbon steel substrate, plasma sprayed). As-sprayed surface roughness 11.4-15.2 µm Ra for Amdry 956 / 450NS; 6.3-8.0 µm Ra for Diamalloy 4008NS. Amdry 956, Metco 450NS, and Metco 450P create an exothermic reaction during spraying that results in a quasi-metallurgical bond with substrates such as steels.”
Journal of Thermal Spray Technology — Effect of Powder Particle Size and Spray Parameters on the Ni/Al Reaction During Plasma Spraying of Ni-Al Composite Powders (PMC, peer-reviewed)
“Particle size is the dominant factor controlling the exothermic Ni-Al reaction. S-powder (30-50 µm) particles reach ~2,436°C ± 81°C at 60 mm spray distance, approaching aluminum's boiling point (2,470°C). Adiabatic temperature increment from the Ni+Al → NiAl reaction is 1,400-2,000 K. Fully reacted S-powder deposits show 51.3 MPa adhesive strength, ~10% oxide content, and 4-5% porosity. M-powder (53-75 µm) and L-powder (75-90 µm) cannot complete the reaction even at high plasma arc power (42 kW), giving lower bond strength and higher porosity. The exothermic reaction raises particle temperature during spray, induces local substrate melting on impact, and produces metallurgical bonding at inter-lamellar interfaces — the 'self-bonding effect.'”
Cincinnati Thermal Spray — 85/15 Nickel Aluminum (CT5102-1) Research Page
“During plasma spray, nickel alloys with aluminum to produce nickel aluminide through an exothermic reaction — particles melt in the plasma flame and 'use the exothermic heat to get hotter as they travel to the part,' then adhere through 'actual diffusion of part of the particles into the substrate.' Primary applications: bond coat for wear, thermal-barrier, and corrosion-resistant systems; build-up of worn parts; fretting, erosion, and high-temperature oxidation protection. Typical thickness 0.003-0.006 in (3-6 mils) as bond coat, 0.015-0.025 in (15-25 mils) as build-up.”
Coatings Journal — Ni-Al and NiO-Al Composite Coatings by Combustion-Assisted Flame Spraying (MDPI, peer-reviewed)
“Ni-Al composite powders deposit self-bonding coatings as bond coats for ceramic topcoats due to the exothermic reaction between nickel and aluminum. As aluminum melts in the flame and contacts the heated nickel, NiAl forms by an exothermic reaction releasing large amounts of heat, aiding the spray coating and encouraging further reactions. NiAl phase hardness approximately 250 HV 0.04; coating porosity and roughness vary with processing parameters, with volume porosity ranging from 4.9 ± 0.8% to 7.8 ± 1.1% across the parameter window studied.”
Coatings Journal — High-Temperature Oxidation Resistance of NiAl Intermetallic Formed In Situ by Thermal Spraying (MDPI, peer-reviewed)
“NiAl intermetallic coatings formed in situ by thermal spraying exhibit self-bonding behavior driven by the exothermic Ni+Al → NiAl reaction during deposition. The formation of intermetallic compound during the spray process leads to metallurgical bonding due to the high exothermicity of the formation reaction. NiAl coatings demonstrate good oxidation resistance in high-temperature service due to formation of a protective Al2O3 scale at temperature.”
Oerlikon Metco myMetco — Metco 450NS Nickel – 5% Aluminum Thermal Spray Powder
“Metco 450NS is a mechanically clad nickel-aluminum composite powder (Ni + 4.0-5.5% Al), nominal particle range -90 +45 µm, apparent density 3.7 ± 0.3 g/cc. Exothermic reaction during spray makes the coating self-bonding to steel substrates. Applied by atmospheric plasma spray or combustion powder Thermospray. Used as a low-temperature bond coat and for general salvage and restoration on steel and nickel-based substrates. Qualified under Avio 4800M/3, CFM International CP 6007, GE B50A891, Honeywell EMS 57746, Pratt & Whitney PWA 1337, Rolls-Royce EMS 56757, Rolls-Royce RRMS 40022, SAE International AMS 5739, and others.”
Journal of Thermal Spray Technology — Effect of Powder Particle Size and Spray Parameters on the Ni/Al Reaction During Plasma Spraying of Ni-Al Composite Powders (Springer, peer-reviewed)
“Systematic investigation of particle-size and plasma-arc-power effects on the Ni-Al exothermic reaction during plasma spraying. Confirms that particles smaller than 50 µm undergo complete exothermic reaction and achieve the self-bonding effect, while larger particles fail to complete the reaction even at 42 kW arc power. Coating properties — bond strength, oxide content, porosity — track directly with reaction completion.”
Journal of Thermal Spray Technology — Reactive Spraying of Nickel-Aluminide Coatings
“Reactive spraying of nickel and aluminum produces coatings consisting of Ni, Al, Ni3Al, NiAl3, Ni5Al3, NiAl, and Al2O3 phases depending on experimental conditions. The formation of phases is attributed to the exothermic reaction between splats of aluminum and nickel during spray deposition, which produces metallurgical bonding and the characteristic self-bonding behavior of the Ni-Al system.”
Oerlikon Metco Thermal Spray Materials Guide (2015)
“Nickel-aluminum thermal-spray materials are the baseline bond-coat family across the Oerlikon Metco portfolio, used under ceramic topcoats, abradables, and wear-resistant overlays on steel and nickel-base substrates. The family includes both 95/5 (Amdry 956, Metco 450NS, Metco 480NS, Diamalloy 4008NS) and 80/20 (Metco 404NS, Metco 2101ZB, Metco 447NS, Metco 405A wire) chemistries, selected based on service temperature ceiling and required bond strength.”

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 Aluminide

Technical data

Where it earns its keep

Where it doesn't

Typical applications

Wear modes addressed

Industries

Substrates

Which process, when?

Sources

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