Mu-Metal,Permalloy,,E FORU

### **Mu-Metal / Permalloy** **High Permeability Nickel-Iron Soft Magnetic Alloy for Electronic Applications** --- #### **1. Overview** **Permalloy**, often referred to generically as **Mu-Metal**, is a nickel-iron soft magnetic alloy renowned for its exceptionally high magnetic permeability and low coercivity. Developed in the early 20th century, this alloy exhibits superior magnetic softness, making it ideal for applications requiring efficient magnetic flux transfer and effective magnetic shielding. Permalloy achieves its optimal magnetic properties through a critical heat treatment process that involves annealing in a protective hydrogen atmosphere and rapid cooling. --- #### **2. Chemical Composition (Weight %)** The typical composition of Permalloy (80% nickel grade) is outlined below. The balance is Iron (Fe). | Element | Content (%) | Key Function | | :--- | :--- | :--- | | **Nickel (Ni)** | 78.0 - 81.0 | Primary element enabling high permeability and near-zero magnetostriction. | | **Iron (Fe)** | Balance | Forms the ferromagnetic matrix. | | **Molybdenum (Mo)** | 3.0 - 4.0 | Increases electrical resistivity and enhances magnetic softness. | | **Manganese (Mn)** | 0.50 - 1.0 | Aids in deoxidation and improves workability. | | **Silicon (Si)** | 0.10 - 0.30 | Enhances magnetic properties and reduces core losses. | | **Chromium (Cr)** | 0.10 - 0.30 | Optional addition for specific property modifications. | | **Carbon (C)** | 0.02 max | Strictly controlled to prevent magnetic aging and hysteresis losses. | | **Sulfur (S)** | 0.010 max | Minimized to prevent magnetic property degradation. | --- #### **3. Physical Properties** | Property | Value / Condition | | :--- | :--- | | **Density** | 8.70 g/cm³ (0.314 lb/in³) | | **Melting Point** | ~ 1450 °C (2642 °F) | | **Curie Temperature** | ~ 460 °C (860 °F) | | **Electrical Resistivity** | 0.55 μΩ·m at 20°C (68°F) | | **Thermal Conductivity** | 18.5 W/m·K (128 Btu·in/hr·ft²·°F) at 20°C (68°F) | | **Specific Heat Capacity** | 490 J/kg·K (0.117 Btu/lb·°F) at 20°C (68°F) | | **Mean Coefficient of Thermal Expansion** | 20 - 400°C (68 - 752°F): **12.5 x 10⁻⁶/°C** (6.9 x 10⁻⁶/°F) | | **Modulus of Elasticity** | 158 GPa (22.9 x 10⁶ psi) at 20°C (68°F) | --- #### **4. Magnetic Properties (After Hydrogen Anneal)** | Property | Value | | :--- | :--- | | **Initial Permeability (μi)** | 20,000 - 40,000 | | **Maximum Permeability (μmax)** | 70,000 - 120,000 | | **Saturation Induction (Bs)** | 0.70 - 0.80 T | | **Coercive Force (Hc)** | 1.0 - 2.0 A/m | | **Residual Induction (Br)** | 0.10 - 0.30 T | | **Hysteresis Loss** | Extremely Low | --- #### **5. Mechanical Properties (Annealed Condition)** | Property | Value at Room Temperature | | :--- | :--- | | **Tensile Strength** | 500 MPa (73 ksi) | | **Yield Strength (0.2% Offset)** | 330 MPa (48 ksi) | | **Elongation (in 50 mm)** | 40% | | **Hardness (Rockwell B)** | 70 HRB | | **Vickers Hardness** | 130 HV | --- #### **6. International Standards** Permalloy conforms to the following international specifications: * **ASTM:** * **A753:** Wrought Nickel-Iron Soft Magnetic Alloys * **IEC:** * **IEC 60404-8-6:** Soft magnetic metallic materials * **MIL:** * **MIL-N-14411C:** Composition 1 * **JIS:** * **JIS C 2531:** Iron-nickel magnetic alloys * **National Standards:** * Various national specifications for high-permeability alloys --- #### **7. Product Applications** Permalloy is critical in numerous electronic and magnetic applications: * **Magnetic Shielding:** * CRT display shields * Electron microscope columns * Medical imaging equipment * Precision measurement instruments * **Transformer Cores:** * Instrument transformers * Pulse transformers * High-frequency transformers * Magnetic amplifiers * **Telecommunications:** * Telephone loading coils * Inductor cores * Magnetic recording heads * RF transformers * **Aerospace & Defense:** * Fluxgate magnetometers * Gyroscope components * Satellite magnetic controls * Navigation systems * **Research Equipment:** * Mass spectrometer components * Particle accelerator magnets * Scientific instrument shields --- #### **8. Key Characteristics & Advantages** * **Extremely High Permeability:** Maximum permeability exceeding 100,000 for superior magnetic performance * **Near-Zero Magnetostriction:** Minimal dimensional changes during magnetization * **Low Coercive Force:** Excellent soft magnetic characteristics with minimal hysteresis * **High Magnetic Shielding Effectiveness:** Attenuates magnetic fields by factors up to 1000x * **Excellent High-Frequency Response:** Maintains properties at elevated frequencies * **Good Mechanical Workability:** Can be rolled to thin gauges and formed into complex shapes * **Predictable Aging Characteristics:** Stable magnetic properties over time * **Proven Historical Performance:** Over a century of reliable application in critical systems --- **Disclaimer:** *Permalloy is a registered trademark. The values provided are typical and for informational purposes only. For critical applications, always consult official material data sheets. Permalloy requires specialized hydrogen atmosphere annealing and is extremely sensitive to mechanical stress after final heat treatment. Proper handling and stress relief procedures are essential for maintaining optimal magnetic properties.*

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 1693 gallon liquid totes Special package is available on request.