AMS 5884
AMS 5884 covers Incoloy 909 (UNS N19909) controlled-thermal-expansion (CTE) precipitation-hardenable nickel-iron-cobalt alloy in bar and billet form. Incoloy 909 (38%Ni, 41%Fe, 13%Co, 4.7%Nb, 1.5%Ti) has a very low and precisely controlled coefficient of thermal expansion between ambient temperature and 1200°F — typically 7.7 × 10⁻⁶/°F versus approximately 9.5–10.0 × 10⁻⁶/°F for standard superalloys — which is the primary engineering property that makes it uniquely suited for gas turbine engine sealing systems where differential thermal expansion between dissimilar materials must be minimized.
The bar and billet form covered by AMS 5884 is used for machined engine sealing rings, knife-edge seals, structural retaining rings, and precision structural components in gas turbine hot sections. Precipitation hardening develops 130 ksi yield strength — sufficient for the structural loading in sealing ring applications while the CTE matching is maintained through the operating temperature range of 70–1200°F.
Mechanical Properties (AMS 5884 — Incoloy 909, Age-Hardened)
- Minimum Yield Strength (0.2% offset): 130,000 psi (896 MPa)
- Minimum Ultimate Tensile Strength: 155,000 psi (1,069 MPa)
- Minimum Elongation: 12% (2-inch gauge)
- Minimum Reduction in Area: 15%
- CTE (70–1200°F): ≈ 7.7 × 10⁻⁶/°F (approximately 20% lower than standard nickel superalloys)
- Bar diameters: 0.375 inch to 10.000 inches
AMS 5884 bar is supplied in the solution-treated condition for machining. Final age hardening is performed after machining (typically by the component manufacturer) per the following cycle: 1800°F (982°C) solution treat, water quench; age at 1400°F (760°C) for 8 hours, air cool; re-age at 1200°F (649°C) for 8 hours, air cool. This two-step aging sequence precipitates Ni₃Ti gamma-prime and eta-phase strengthening particles while locking in the controlled low-CTE microstructure needed for the sealing system dimensional requirements. Age hardening in the machined component simultaneously controls final dimensions and develops properties.
- Gas turbine engine knife-edge seals and labyrinth sealing rings
- Turbine and compressor case structural retaining rings requiring matched CTE
- Compressor discharge structural flanges and bolted joints with multi-material CTE requirements
- Precision aerospace actuator components requiring dimensional stability across 70–1200°F
- Gas turbine engine instrumentation and measurement hardware requiring CTE control
- Aerospace structural retaining rings in hot-section assemblies with ceramic or titanium mating parts
AMS 5892 — Incoloy 909 Sheet
Incoloy 909 sheet and strip — the companion thin-section product form for formed engine sealing elements and structural sheet in 909 CTE alloy.
Inconel 718
Standard gas turbine superalloy (AMS 5662/5663/5664) — 180–200 ksi strength for applications where CTE control is not required and maximum strength governs.
Certified Material for Critical Service
AMS 5884 mill test reports document Incoloy 909 chemistry (Ni 36–40%, Fe 38–44%, Co 12–16%, Nb 4.3–5.2%, Ti 1.3–1.7%), solution-treated condition, and mechanical properties in the solution-treated test condition (or after aging if lot release testing includes aging). The solution-treated condition is confirmed by hardness; the age-hardened properties are typically verified by the component manufacturer on production pieces. For Incoloy 909 sheet see AMS 5892; for plate see AMS 5893.