Nickel-iron (Ni-Fe) alloys are a class of materials known for their unique magnetic, thermal, and mechanical properties, making them essential in industries ranging from electronics to aerospace. These alloys typically contain 30–80% nickel, with the balance being iron and small additions of other elements (e.g., molybdenum, chromium, or copper) to enhance specific characteristics.
Key Types of Nickel-Iron Alloys
These alloys are optimized for magnetic performance in AC/DC applications.
Permalloy (Ni ~80%, Fe ~20%)
– Properties: Extremely high magnetic permeability. Low coercivity (easy magnetization/demagnetization). Good corrosion resistance.
– Applications: Transformer cores, magnetic shielding. Sensors, inductors, and telecommunications equipment.
Supermalloy or Mu-Metal(Ni ~79%, Fe ~15%, Mo ~5%)
– Properties: Even higher permeability than Permalloy. Very low hysteresis loss.
– Applications: Precision instruments, high-frequency transformers.
These alloys maintain minimal dimensional changes with temperature fluctuations.
Invar (Ni ~36%, Fe ~64%)
– Properties: Near-zero thermal expansion at room temperature. Used where dimensional stability is critical.
– Applications: Precision instruments (pendulum clocks, optical mounts). Aerospace structures (satellite components). LNG storage tanks (cryogenic applications).
These alloys combine mechanical robustness with corrosion resistance.
Nilo Alloys (Ni ~42-50%, Fe balance)
– Properties: Intermediate thermal expansion. Good brazing & sealing compatibility.
– Applications: Thermostats, electronic housings.
Key Properties of Nickel-Iron Alloys
Property | Soft Magnetic (Permalloy) | Controlled Expansion (Invar) |
Nickel Content (%) | 70-80% | 36% |
Thermal Expansion | Moderate | Near-zero |
Magnetic Behavior | High permeability | Weakly magnetic |
Key Strength | Magnetic performance | Dimensional stability |
Choose the Alloy by Industry
– Transformers, inductors, magnetic shields (Permalloy).
– Semiconductor packaging (Kovar).
– Satellite components (Invar for stability).
– Jet engine parts (high-strength Ni-Fe alloys).
– Power distribution systems (soft magnetic alloys).
– Cryogenic storage (Invar for LNG tanks).
– Sensors, fuel injection systems (high-permeability alloys).