FeNi 50/50 alloy,Nickel-iron alloy，1

### **Introduction to FeNi 50/50 (Nickel-Iron 50/50) Alloy** **FeNi 50/50**, also known as **Alloy 50** or **Nickel-Iron 50/50**, is a controlled expansion alloy composed of approximately equal parts nickel and iron. It is part of a family of nickel-iron alloys designed to exhibit specific thermal, magnetic, and mechanical properties. The primary characteristic of FeNi 50/50 is its **relatively high and constant permeability at low magnetic field strengths**, combined with a **Curie temperature** around 500°C (932°F). Unlike its more famous cousin, Invar (FeNi36), which is known for its low thermal expansion, FeNi 50/50 is optimized for its magnetic performance in AC and DC applications. --- ### **Chemical Composition (Weight %, typical)** The composition is tightly controlled to ensure consistent magnetic and physical properties. | Element | Minimum | Maximum | Key Function | | :--- | :--- | :--- | :--- | | **Nickel (Ni)** | 49.0 | 51.0 | Determines the fundamental magnetic and thermal characteristics of the alloy matrix. | | **Iron (Fe)** | **Balance** | | The other primary constituent, forming the ferritic base. | | **Manganese (Mn)** | 0.3 | 0.6 | Acts as a deoxidizer and improves hot workability. | | **Silicon (Si)** | - | 0.10 | Kept low to prevent embrittlement and maintain magnetic softness. | | **Carbon (C)** | - | 0.03 | Kept very low to prevent the formation of carbides, which degrade magnetic properties. | | **Cobalt (Co)** | - | 0.5 | Incidental impurity. | | **Copper (Cu)** | - | 0.2 | Incidental impurity. | | **Sulfur (S)** | - | 0.015 | Harmful impurity; kept extremely low. | *The precise 50/50 Ni/Fe ratio is critical for achieving its specific Curie temperature and saturation induction.* --- ### **Physical Properties (Typical)** * **Density:** 8.25 g/cm³ (0.298 lb/in³) * **Melting Range:** ~1425 - 1475 °C (~2600 - 2690 °F) * **Thermal Expansion Coefficient (CTE):** ~10.0 μm/m·°C (20-400°C) *[Note: Higher than Invar but lower than steel]* * **Thermal Conductivity:** 19.5 W/m·K at 100°C * **Electrical Resistivity:** 45 μΩ·cm at 20°C * **Curie Temperature:** ~500 °C (~932 °F) * **Saturation Induction (Bsat):** ~1.6 Tesla --- ### **Mechanical Properties (Typical at Room Temperature, Annealed Condition)** * **Tensile Strength:** 517 - 586 MPa (75 - 85 ksi) * **Yield Strength (0.2% Offset):** 276 - 345 MPa (40 - 50 ksi) * **Elongation:** 30 - 40% * **Hardness (Rockwell B):** 65 - 75 --- ### **Key Characteristics and Product Applications** #### **Key Characteristics:** 1. **High Permeability at Low Field Strengths:** Exhibits high magnetic permeability, meaning it is easily magnetized by weak magnetic fields. This makes it a "soft" magnetic material. 2. **Controlled Thermal Expansion:** Its coefficient of thermal expansion is lower than that of carbon steel, making it dimensionally stable over a range of temperatures. 3. **Well-Defined Curie Temperature:** Its magnetic properties sharply decline at its Curie point (~500°C), which can be a useful design feature in temperature-sensitive devices. 4. **Good Saturation Induction:** Can support a high magnetic flux density before becoming saturated. #### **Primary Applications:** FeNi 50/50 is primarily used in applications requiring precise and efficient magnetic performance. * **Magnetic Shielding:** Used to fabricate shields that protect sensitive electronic components from external magnetic fields. * **Transformers and Inductors:** Laminations and cores for small transformers, especially in aerospace and military applications where performance is critical. * **Relays and Magnetic Amplifiers:** Core material where high permeability and low core loss are required. * **Electronic Sensors:** Used in the cores of current sensors and other magnetic field sensing devices. * **Hermetic Seals:** Used in glass-to-metal sealing applications for electronic packages, where its thermal expansion can be matched to certain types of glass. --- ### **International Standards** FeNi 50/50 is covered by several international standards, though specifications can vary slightly between different standard organizations. | Standard Organization | Standard Number | Designation / Description | | :--- | :--- | :--- | | **ASTM International** | **ASTM F30** | Standard Specification for Iron-Nickel Sealing Alloys (Covers alloys like 52Fe/48Ni, which are very similar). | | **Society of Automotive Engineers (SAE)** | **AMS 7724** | Covers 49-51% Nickel-Iron alloy strip for magnetic applications. | | **European Standards** | **EN 10088** (or proprietary) | Often specified by chemical composition and magnetic properties rather than a single universal standard. | | **International Electrotechnical Commission (IEC)** | **IEC 60404-8-6** | Standard for soft magnetic metallic materials. | | **Unified Numbering System (UNS)** | **K94800** | This UNS number is sometimes associated with 50Ni-50Fe type alloys. | **Note:** The exact nomenclature and specifications can be proprietary or vary by manufacturer. It is crucial to define the required magnetic and physical properties (e.g., permeability at a specific field strength, core loss, etc.) when procuring this material, as its performance is highly dependent on its final heat treatment and processing history.

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 3270 gallon liquid totes Special package is available on request.