Alloy 115 is a high-strength, precipitation-hardenable nickel-chromium-cobalt superalloy. This datasheet presents the material within the American / international (AMS / aerospace) standard system.
Developed as a creep-resisting alloy for service at temperatures up to about 1010 °C (1850 °F), Alloy 115 was created principally for turbine blades in aircraft gas turbines. It is a nickel-chromium-cobalt alloy strengthened by a molybdenum addition for solid-solution strengthening together with high levels of aluminium and titanium, which form a large volume fraction of the gamma-prime (γ′, Ni₃(Al,Ti)) phase for exceptional high-temperature strength and creep resistance. It offers superior oxidation resistance and high-temperature strength, and is hardened by solution treatment followed by ageing.
Typical applications include gas-turbine blades, nozzle guide vanes and disc components, exhaust valves, and high-temperature fasteners and engine components subject to severe stress and cyclic loading.
Typical values, fully heat-treated condition.
| Property | Value | Unit |
|---|---|---|
| Density | 7.85 | g/cm³ |
| Melting range | 1275–1335 | °C |
| Elastic modulus | 224 | GPa |
| Coefficient of thermal expansion (20–100 °C) | 12.0 | µm/m·°C |
| Thermal conductivity (20 °C) | 10.7 | W/m·K |
| Specific heat (20 °C) | 448 | J/kg·K |
| Structure | Austenitic (FCC) + γ′ | — |
Specified for the γ′ precipitation-hardened Ni-Cr-Co superalloy (Nimonic 115).
| Element | Symbol | Min % | Max % | Role in Alloy |
|---|---|---|---|---|
| Nickel | Ni | Balance | — | Base element; γ′ matrix |
| Chromium | Cr | 14.0 | 16.0 | Oxidation resistance |
| Cobalt | Co | 13.0 | 15.5 | Solid-solution; raises γ′ stability |
| Aluminium | Al | 4.50 | 5.50 | γ′ (Ni₃Al) precipitation strengthening |
| Titanium | Ti | 3.50 | 4.50 | γ′ (Ni₃Ti) precipitation strengthening |
| Molybdenum | Mo | 3.0 | 5.0 | Solid-solution strengthening |
| Carbon | C | 0.12 | 0.20 | Carbide formation |
| Iron | Fe | — | 1.0 | Residual |
| Zirconium | Zr | — | 0.10 | Grain-boundary strengthening |
| Boron | B | — | 0.20 | Grain-boundary strengthening |
Nominal: nickel-chromium-cobalt γ′ precipitation-hardened superalloy with Mo, high Al and Ti.
Fully heat-treated (solution-treated and aged) condition, typical values.
| Condition | Property | Value |
|---|---|---|
| Solution treated & aged | Tensile strength (UTS) | ≥1240 MPa (180 ksi) |
| Solution treated & aged | 0.2% yield strength | ≥865 MPa (125 ksi) |
| Solution treated & aged | Elongation at break | ≥12 % |
| At elevated temperature | Creep / rupture strength | Excellent to ~1010 °C |
| — | Elastic modulus | 224 GPa |
Confirm against the mill test report. The high γ′ volume fraction gives outstanding creep and rupture strength at turbine-blade operating temperatures.
| Environment | Performance | Notes |
|---|---|---|
| High-temperature oxidation | Excellent | High chromium + aluminium |
| Hot corrosion | Very Good | Turbine-blade service |
| Creep / stress rupture | Excellent | High γ′ content |
| Thermal fatigue | Very Good | Combined with high strength |
| Aqueous corrosion | Moderate | Not the primary design purpose |
The high chromium and aluminium contents give excellent high-temperature oxidation resistance, while the large γ′ volume fraction provides the outstanding creep and stress-rupture strength required for gas-turbine blade service to about 1010 °C.
A γ′ precipitation-hardenable superalloy; strengthened by solution treatment followed by ageing.
Solution Treatment Solution treat at approximately 1190 °C (2175 °F) for about 1.5 hours and air cool, dissolving the γ′ for subsequent controlled re-precipitation.
Precipitation Hardening (Ageing) Age at approximately 1100 °C (2012 °F) for about 6 hours and air cool, precipitating the γ′ (Ni₃(Al,Ti)) phase that develops the alloy's high-temperature strength and creep resistance.
Weldable with care; the high aluminium-plus-titanium content makes the alloy susceptible to strain-age cracking, so welding of highly stressed, restrained components requires careful procedure. Matching alloy filler is used, or the nearest alloy richer in nickel, cobalt, chromium and molybdenum.
| Welding Process | Applicability | Filler / Consumable |
|---|---|---|
| GTAW / TIG | With care | Matching 115 filler |
| EBW / laser | With care | Autogenous or matching filler |
| Post-weld | Recommended | Solution treat and age |
Weld with matching filler and clean surfaces; manage restraint to avoid strain-age cracking, and apply post-weld heat treatment.
Machining Guidelines
| Parameter | Recommendation |
|---|---|
| Machinability | Difficult; high strength, work-hardens, rigid setups |
| Tooling | Carbide; slow speeds, positive feeds |
| Coolant | Water-based coolant for high-speed operations |
Forming Processes
| Process | Notes |
|---|---|
| Cold forming | Good ductility but high strength; heavy-duty lubricants, clean after forming |
| Hot forming | Performed hot; solution treat and age afterward |
| Industry | Typical Components | Key Requirements |
|---|---|---|
| Aero gas turbine | Turbine blades, nozzle guide vanes | Creep + oxidation resistance |
| Power generation | Disc components, hot-section hardware | High-temperature strength |
| Motorsport / engine | Exhaust valves, fasteners, springs | Strength + surface stability |
| High-temperature | Severely stressed cyclic components | Creep + thermal-fatigue resistance |
| Product Form | Standard | Notes |
|---|---|---|
| Bar, billet and forgings | AMS 5911 · BS HR4 | γ′-hardened superalloy |
| Extruded / cold-worked section | AECMA PrEN 2196 / 2197 | Turbine-blade stock |
| Tube | Nimonic 115 | Special order |
| Parts | Nimonic 115 | Solution-treated and aged |
γ′ precipitation-hardened nickel-chromium-cobalt superalloy. AMS 5911.
| Alloy | Cr % | Co % | γ′ Formers | Best Used For |
|---|---|---|---|---|
| Alloy 115 | 14–16 | 13–15.5 | Al + Ti (high) | High-γ′ turbine-blade superalloy; creep strength to ~1010 °C |
| Alloy 105 | 14–16 | 18–22 | Al + Ti + Mo | High-temperature creep-resistant blade alloy |
| Alloy 90 | 18–21 | 15–21 | Al + Ti | Creep-resistant blade / disc alloy |
| Alloy 80A | 18–21 | ≤2 | Al + Ti | Age-hardened Ni-Cr; valves, fasteners |
| Alloy 263 | 19–21 | 19–21 | Al + Ti | Fabricable γ′ sheet / fabrication alloy |




