Permalloy Wire,

Permalloy Wire - Introduction with Composition, Properties, Applications and Product Forms

Permalloy is a family of nickel-iron alloys renowned for their exceptional magnetic properties, including high magnetic permeability, low coercivity, and excellent magnetic softness. These characteristics make permalloy a cornerstone material in magnetic shielding, transformers, sensors, and precision electronic components. Available in a comprehensive range of forms to meet diverse industrial needs, permalloy products include Bar (Round bar, Flat bar), Ribbon, Wire, Rods, Tube, Pipe, Foil, Plate, Sheet, Strip, and Forging Stock. Permalloy Wire, in particular, is valued for its precise magnetic performance, flexibility, and uniformity, making it ideal for intricate coils, sensors, and magnetic shielding applications in electronics, telecommunications, and aerospace industries. Below is a detailed overview of its chemical composition, key properties, practical applications, and available product forms.

Chemical Composition

The chemical composition of permalloy varies slightly depending on the specific grade, but all formulations are centered around a nickel-iron matrix optimized for magnetic performance. The typical composition (by weight) of a standard permalloy grade is as 

follows

Nickel (Ni): 70-80% (the primary alloying element, responsible for enhancing magnetic permeability and reducing coercivity)

Iron (Fe): 20-30% (balances the alloy, contributing to structural stability while supporting magnetic properties)

Molybdenum (Mo): 0-5% (in molybdenum-permalloy grades, improves permeability and increases electrical resistivity, reducing eddy current losses)

Copper (Cu): 0-2% (in some grades, enhances corrosion resistance and refines grain structure)

Manganese (Mn): 0.5-1.0% (aids in deoxidation during manufacturing, improving ductility and magnetic uniformity)

Carbon (C): ≤ 0.03% (kept low to avoid carbide formation, which can degrade magnetic properties)

Silicon (Si): ≤ 0.3% (controlled to maintain purity and avoid oxide inclusions that disrupt magnetic domains)

Sulfur (S): ≤ 0.01% (strictly limited to prevent grain boundary embrittlement and preserve magnetic softness)

The most common grade, 78% nickel-iron permalloy, delivers a balance of high permeability (up to 80,000) and low coercivity (≤ 0.8 A/m), while molybdenum-containing grades (e.g., 79% Ni, 17% Fe, 4% Mo) offer even higher permeability and better high-frequency performance, making them suitable for advanced electronic applications.

Key Properties

Permalloy (including Permalloy Wire) exhibits a unique set of magnetic and mechanical properties that make it indispensable in magnetic and electronic applications:

Magnetic Properties:

Magnetic permeability (initial/ maximum): Initial permeability (μ₀) up to 20,000; maximum permeability (μₘ) up to 100,000 (significantly higher than pure iron, enabling efficient magnetic flux conduction)

Coercivity (Hc): ≤ 1.0 A/m (extremely low, indicating "magnetic softness" and easy magnetization/demagnetization)

Saturation induction (Bs): 0.8-1.0 T (moderate saturation, suitable for low to medium magnetic field applications)

Curie temperature: 450-500°C (the temperature above which magnetic properties diminish, ensuring stability in ambient and moderate-heat environments)

Electrical resistivity: 25-60 μΩ·cm (higher than pure iron, reducing eddy current losses in alternating current (AC) applications)

Mechanical Properties (annealed condition):

Tensile strength: 400-550 MPa (58,000-79,800 psi)

Yield strength (0.2% offset): 150-250 MPa (21,800-36,300 psi)

Elongation (in 50 mm): 20-40% (excellent ductility, enabling forming into wires, ribbons, and complex shapes)

Hardness: 120-180 HB (Brinell hardness, reflecting good machinability and workability)

Physical Properties:

Density: 8.6-8.8 g/cm³ (0.310-0.318 lb/in³)

Thermal conductivity: 10-15 W/(m·K) at 20°C (68°F)

Coefficient of thermal expansion: 12-15 μm/(m·K) (20-100°C)

Melting point: 1430-1480°C (2594-2696°F)

Product Forms

Permalloy is manufactured in a diverse range of forms to accommodate specialized magnetic and electronic applications across industries:

Bar: Available as Round bar (diameters from 5 mm to 100 mm) and Flat bar (thickness 3 mm to 50 mm, width 10 mm to 200 mm), used for machining magnetic cores, shields, and structural components in magnetic devices.

Ribbon: Thin, flat strips (thickness 0.01 mm to 0.5 mm, width 1 mm to 50 mm) ideal for high-frequency transformers, inductors, and magnetic sensors, where minimal eddy current losses are critical.

Wire: Permalloy Wire (diameters 0.02 mm to 5 mm) offers precise magnetic performance and flexibility, suitable for coils, solenoids, magnetic shielding mesh, and sensor windings.

Rods: Solid cylindrical rods (diameters 2 mm to 30 mm) used in magnetic clamps, precision guides, and small magnetic cores.

Tube and Pipe: Hollow forms (outer diameter 3 mm to 50 mm, wall thickness 0.1 mm to 5 mm) for magnetic shielding of cables, sensors, and electronic components.

Foil: Ultra-thin sheets (thickness 0.001 mm to 0.05 mm) used in high-frequency applications, flexible magnetic shields, and miniature transformers.

Plate and Sheet: Flat forms (plate: thickness 1 mm to 20 mm; sheet: 0.05 mm to 1 mm) for fabricating magnetic shields, transformer cores, and magnetic yokes.

Strip: Narrow, flat strips (thickness 0.05 mm to 1 mm, width 2 mm to 100 mm) for precision magnetic components, such as relay cores and inductor windings.

Forging Stock: Billets and ingots for hot forging into custom magnetic components requiring complex shapes, such as large shielding enclosures.

Applications

The exceptional magnetic properties of permalloy (including Permalloy Wire) across its various forms make it a critical material in industries requiring precise magnetic control and shielding:

Electronics and Telecommunications:

Transformers and inductors: Cores and windings (from ribbon, wire, and sheet) for audio transformers, power supplies, and high-frequency communication devices, leveraging high permeability and low eddy current losses.

Magnetic shielding: Enclosures, tubes, and foil wraps (from plate, tube, and foil) to protect sensitive electronics (e.g., sensors, oscillators) from external magnetic interference.

Sensors and transducers: Coils and cores (from wire and ribbon) in magnetic field sensors, current transformers, and position detectors, where high sensitivity is critical.

Aerospace and Defense:

Avionics: Magnetic shields for navigation systems, radar components, and communication equipment (from sheet, tube, and foil) to ensure signal integrity in high-interference environments.

Missile guidance systems: Precision magnetic cores and coils (from wire and ribbon) for gyroscopes and magnetic compasses, requiring stable magnetic performance.

Military communication: High-frequency transformers and inductors (from ribbon and wire) for secure radio systems, where low noise and high efficiency are essential.

Medical Devices:

Medical imaging: Magnetic shielding components (from plate and sheet) for MRI machines, protecting sensitive electronics from the strong magnetic fields generated by the scanner.

Diagnostic equipment: Current sensors and magnetic transducers (from wire and ribbon) in devices such as EKG machines, ensuring accurate signal detection.

Industrial and Scientific Instruments:

Magnetic measurement tools: Calibration cores and shielding (from wire, sheet, and tube) for magnetometers and gaussmeters, enabling precise magnetic field measurements.

Power electronics: Inductors and chokes (from ribbon and wire) in variable frequency drives and power converters, reducing energy losses.

Scientific research: Magnetic shields and coils (from foil, wire, and plate) for experiments in physics and material science, isolating equipment from ambient magnetic fields.

Specialized Applications by Form:

Wire: Coils for solenoids, magnetic shielding mesh, and sensor windings in precision instruments.

Ribbon: High-frequency transformer cores and inductor windings, where thin dimensions minimize eddy currents.

Foil: Flexible magnetic shields for cables and miniature electronics, such as wearables and IoT devices.

Plate/Sheet: Large magnetic shields for laboratories, data centers, and industrial equipment.

In summary, Permalloy (including Permalloy Wire) — available in forms from Bar and Wire to Plate and Forging Stock — delivers exceptional magnetic permeability, low coercivity, and versatility. Its diverse product forms enable tailored solutions across electronics, aerospace, medical, and industrial sectors, establishing it as a critical material in applications requiring precise magnetic control and shielding.

Packing of Standard Packing: 

Typical bulk packaging includes palletized plastic 5 gallon/25 kg. pails, fiber and steel drums to 1 ton super sacks in full container (FCL) or truck load (T/L) quantities. Research and sample quantities and hygroscopic, oxidizing or other air sensitive materials may be packaged under argon or vacuum. Solutions are packaged in polypropylene, plastic or glass jars up to palletized 1622 gallon liquid totes Special package is available on request.