Nickel alloys are high-performance engineering materials in which nickel is the primary element (typically 30–75% or higher). They are engineered for extreme environments involving high temperature, stress, corrosion, oxidation, creep, fatigue, and thermal cycling.
Classification of Nickel Alloys
| Family | Primary Alloying Elements | Key Purpose |
|---|---|---|
| Ni–Cu | Copper | Seawater & HF resistance |
| Ni–Cr | Chromium | Oxidation & heat resistance |
| Ni–Cr–Fe | Cr, Fe | High-temperature corrosion |
| Ni–Mo | Molybdenum | Reducing acid resistance |
| Ni–Cr–Mo | Cr, Mo | Severe chemical environments |
| Ni-Base Superalloys | Cr, Co, Al, Ti | Extreme strength & creep |
| Ni–Fe | Iron | Controlled expansion (Invar) |
| Ni–Ti / Ni–Al | Titanium / Aluminum | Shape memory & intermetallics |
Typical Chemical Composition Ranges
| Element | wt% Range | Function |
|---|---|---|
| Nickel (Ni) | 30 – 75+ | Base metal |
| Chromium (Cr) | 10 – 30 | Oxidation & corrosion resistance |
| Molybdenum (Mo) | 5 – 30 | Pitting & crevice resistance |
| Iron (Fe) | 0 – 30 | Cost control & strength |
| Cobalt (Co) | 0 – 20 | High-temperature strength |
| Aluminum (Al) | 0.5 – 6 | Precipitation strengthening |
| Titanium (Ti) | 0.5 – 5 | γ′ formation |
| Niobium (Nb) | 0 – 6 | Creep & weldability |
| Tungsten (W) | 0 – 10 | Solid-solution strengthening |
Mechanical Properties
| Property | Typical Range |
|---|---|
| Tensile Strength | 600 – 1600 MPa |
| Yield Strength | 250 – 1200 MPa |
| Elongation | 10 – 45% |
| Hardness | 150 – 450 HB |
| Creep Resistance | Excellent |
| Fatigue Strength | Very high |
Physical Properties
| Property | Typical Value |
|---|---|
| Density | 8.1 – 8.9 g/cm³ |
| Melting Range | 1250 – 1400 °C |
| Thermal Conductivity | 10 – 25 W/m·K |
| Electrical Conductivity | 1 – 10% IACS |
| Elastic Modulus | 200 – 230 GPa |
| Thermal Expansion | 11 – 15 µm/m·K |
Strengthening & Metallurgical Behavior
Nickel alloys possess a stable FCC crystal structure and are strengthened through solid-solution hardening, precipitation hardening (γ′ phase), carbide formation, and grain boundary control. These mechanisms deliver exceptional resistance to creep, fatigue, and thermal shock.
Corrosion & Environmental Resistance
Nickel alloys offer outstanding resistance to oxidation, sulfidation, chloride pitting, stress corrosion cracking, carburization, and metal dusting. They perform exceptionally in acids, alkalis, seawater, and high-pressure steam environments.
Available Forms
Sheets & plates
Rods, bars & wire
Tubes & pipes
Forgings
Castings
Powders (PM & AM)
Fasteners & springs
Applications
Aerospace: turbine blades, combustors, exhaust systems
Power Generation: gas turbines, nuclear reactors, heat exchangers
Oil & Gas: downhole tools, valves, sour gas systems
Chemical Processing: reactors, acid handling equipment
Marine: seawater systems, offshore platforms
Advantages
✔ Extreme high-temperature capability
✔ Superior corrosion resistance
✔ Excellent fatigue & creep performance
✔ Long service life
✔ High reliability in critical systems
Limitations
❌ High material and processing cost
❌ Difficult machining
❌ Higher density than aluminum or titanium
❌ Specialized fabrication required
Why Choose Nickel Alloys?
Nickel alloys are selected when failure is not an option—where extreme heat, corrosive environments, and long-term reliability dominate cost considerations.