Nickel-based alloys play a critical role in aerospace, chemical, electronics, energy, and other industries due to their unique physical, chemical, and mechanical properties. Special alloys such as Hastelloy, Invar, Inconel, and Permalloy each have distinct characteristics, making them suitable for different extreme environments. This article systematically analyzes their compositions, properties, applications, and interrelationships to assist engineers in making informed material selections.
(1) Hastelloy – The King of Corrosion Resistance
Composition: Ni-Mo-Cr (e.g., C-276: Ni-16Mo-16Cr)
Core Properties:
Extreme corrosion resistance: Resistant to strong acids (hydrochloric, sulfuric) and chlorides
High-temperature oxidation resistance .
Stress corrosion cracking resistance
(2) Invar – The Zero-Expansion Material
Composition: Ni-36Fe (thermal expansion coefficient ≈ 0)
Core Properties:
Ultra-low thermal expansion
Low-temperature stability
Typical Applications: Satellite frameworks, optical instruments, superconducting magnet supports
(3) Inconel – The High-Temperature Champion
Composition: Ni-Cr (e.g., Inconel 718: Ni-19Cr-18Fe-5Nb)
Core Properties:
Exceptional high-temperature strength
Oxidation and creep resistance (core material for jet engines)
(4) Permalloy – The Soft Magnetic Master
Composition: Ni-80Fe (ultra-high magnetic permeability)
Core Properties:
Ultra-soft magnetism
Low coercivity (easy magnetization/demagnetization)
Typical Applications: Transformer cores, magnetic shielding, sensors
| Property | Hastelloy | Invar | Inconel | Permalloy |
|---|---|---|---|---|
| Main Composition | Ni-Mo-Cr | Ni-36Fe | Ni-Cr | Ni-80Fe |
| Corrosion Resistance | ★★★★★ | ★★☆ (requires protection) | ★★★★ (high-temp oxidation) | ❌ (N/A) |
| High-Temp Strength | ★★★★ ) | ❌ | ★★★★★ | ❌ |
| Thermal Expansion (×10⁻⁶/K) | Moderate (12-14) | Ultra-low (1.2) | Moderate (14-16) | Moderate (12-13) |
| Magnetic Properties | Weakly magnetic | Weakly magnetic | Weakly magnetic | Ultra-soft magnetic |
3. Interconnections and Synergistic Applications
(1) Commonality in Composition
- Hastelloy & Inconel: Nickel provides corrosion resistance and high-temperature stability.
- Invar & Permalloy: Ni-Fe system enables unique properties (low expansion/high permeability).
(2) Complementary Applications
Jet Engines:Inconel 718 (turbine blades) + Hastelloy X (combustor) → High-temp + corrosion resistance Satellite
Structures:Invar 36 (framework) + Permalloy (magnetic shielding) → Dimensional stability + EMI protection Chemical
Plants:Hastelloy C-276 (reactor) + Monel 400 (piping) → Acid + seawater resistance
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(3) Failure Modes & Solutions
| Alloy Type | Common Failure Causes | Solutions |
|---|---|---|
| Hastelloy | Chloride-induced SCC | Use C-22 (higher Cr content) |
| Invar | Cold-work brittleness | Annealing |
| Inconel | High-temperature creep fracture | Single-crystal casting ( |
| Permalloy | Magnetic degradation | Hydrogen annealing |
Conclusion: How to Select Scientifically?
- Strong acids → Hastelloy (e.g., C-276)
- High temp/pressure → Inconel (e.g., 718)
- Precision dimensional stability → Invar (Invar 36)
- Electromagnetic shielding → Permalloy (80 Permalloy)
Comprehensive analysis of Hastelloy, Invar, Inconel & Permalloy: Performance, applications & future trends for engineering material selection.
Post time: Aug-26-2025