Alloy 48,Nilo 48 ,UNS K94800,E FORU

British Specs:，American Specs: ASTM F30，German Specs:

### **Alloy 48 (Nilo 48) - Product Overview** **Alloy 48**, commercially known as **Nilo 48**, is a controlled expansion iron-nickel alloy specifically designed for matched sealing with hard glasses such as alumina-silicate and borosilicate types. With its unique thermal expansion characteristics, this alloy provides reliable performance in applications requiring precise thermal matching between metal and glass components. * **UNS Designation:** **K94800** * **Common Names:** Nilo 48, Glass Sealing 48, 48Ni-Fe Alloy --- #### **1. Chemical Composition** The chemical composition is carefully balanced to achieve specific thermal expansion properties. | Element | Percentage (%) | Role in the Alloy | |:---|:---|:---| | **Nickel (Ni)** | 47.5 - 48.5 | Primary element controlling CTE characteristics | | **Iron (Fe)** | Balance | Base element providing structural matrix | | **Manganese (Mn)** | 0.10 - 0.30 | Enhances workability and acts as deoxidizer | | **Silicon (Si)** | 0.10 - 0.30 | Improves glass wetting characteristics | | **Carbon (C)** | 0.05 max | Limited to prevent embrittlement | | **Sulfur (S)** | 0.02 max | Controlled impurity | | **Phosphorus (P)** | 0.02 max | Controlled impurity | | **Cobalt (Co)** | 0.50 max | Accidental impurity | --- #### **2. Physical Properties** Specialized physical properties optimized for hard glass sealing applications. | Property | Value / Condition | Notes | |:---|:---|:---| | **Density** | 8.22 g/cm³ (0.297 lb/in³) | | | **Melting Point** | ~1430 °C (2605 °F) | | | **Curie Temperature** | ~480 °C (895 °F) | Higher than Alloy 46 for different CTE profile | | **Thermal Expansion Coefficient (CTE)** | 20-300°C: 8.5-9.2 μm/m·°C
20-400°C: 9.0-9.7 μm/m·°C | Matches hard glasses (borosilicate types) | | **Thermal Conductivity** | 15.2 W/m·K at 20°C | | | **Specific Heat** | 0.46 J/g·°C at 20°C | | | **Electrical Resistivity** | 0.48 μΩ·m at 20°C | | | **Magnetic Properties** | Ferromagnetic below Curie point | | --- #### **3. Mechanical Properties** Typical properties in annealed condition. * **Tensile Strength:** 520-590 MPa (75-86 ksi) * **Yield Strength (0.2% Offset):** 280-350 MPa (41-51 ksi) * **Elongation:** 30-40% in 2 inches * **Modulus of Elasticity:** 154 GPa (22.3 × 10⁶ psi) * **Hardness (Rockwell B):** 68-83 * **Shear Modulus:** 60 GPa (8.7 × 10⁶ psi) --- #### **4. Product Forms & Specific Applications** **Available Forms:** * Sheet & Strip (0.05 mm to 3.0 mm thickness) * Wire (0.1 mm to 6.0 mm diameter) * Rod & Bar (3.0 mm to 150 mm diameter) * Tubing & Pipe * Custom forgings and fabricated components **Primary Applications:** * **Hard Glass Sealing:** Matched seals with borosilicate and alumina-silicate glasses * **Aerospace Electronics:** Critical avionics packages and satellite components * **High-Temperature Lamps:** Seals for high-intensity discharge and specialty lighting * **Microwave Tubes:** Components for radar and communication systems * **Semiconductor Processing:** Equipment components requiring hard glass seals * **Medical Devices:** Implantable device packages and diagnostic equipment * **Scientific Instruments:** Precision instrumentation and laboratory equipment * **Power Electronics:** High-reliability packages for power devices --- #### **5. International Standards** Comprehensive international standardization. | Standard Type | Standard Number | Title / Specification | |:---|:---|:---| | **ASTM** | **ASTM F15** | Standard Specification for Iron-Nickel Sealing Alloys | | **UNS** | **K94800** | Unified Numbering System Designation | | **AMS** | AMS 7722 | Aerospace Material Specification | | **IEC** | IEC 60404-8-6 | Metallic Magnetic Materials Specification | | **DIN** | DIN 1745 | Metallic Materials for Glass-to-Metal Seals | | **JIS** | JIS H 7541 | Alloys for Glass-to-Metal Seals | | **ISO** | ISO 9711 | Metallic Materials for Glass-to-Metal Seals | --- #### **6. Glass Sealing Performance** **Compatible Glass Types:** * Corning 7052, 7056, 7062 * Schott AR-Glass, SD-2 * Kimble EN-1, EG-6 * Various borosilicate and alumina-silicate compositions **Sealing Characteristics:** * Optimal sealing temperature range: 900-1050°C * Requires controlled atmosphere (hydrogen or vacuum) * Excellent wetting with hard glasses * Minimal interfacial stress during cooling * Superior thermal cycle resistance --- #### **7. Comparison with Other Sealing Alloys** | Property | Alloy 48 | Alloy 46 | Alloy 52 | |:---|:---|:---|:---| | **Nickel Content** | 48% | 46% | 52% | | **CTE (20-300°C)** | 8.5-9.2 μm/m·°C | 9.2-9.8 μm/m·°C | 9.8-10.5 μm/m·°C | | **Curie Temperature** | ~480°C | ~430°C | ~500°C | | **Primary Glass Match** | Hard Glasses | Soft Glasses | Intermediate Glasses | --- #### **8. Manufacturing Considerations** * **Machining:** Good machinability with proper tool geometry and cooling * **Forming:** Excellent cold working characteristics in annealed condition * **Welding:** Suitable for TIG, resistance, and laser welding methods * **Heat Treatment:** Annealing at 850-900°C in protective atmosphere * **Surface Preparation:** Critical for optimal glass sealing performance --- **Summary** **Alloy 48 (Nilo 48, UNS K94800)** represents a specialized member of the iron-nickel sealing alloy family, specifically optimized for hard glass applications. Its carefully controlled thermal expansion characteristics, combined with excellent mechanical properties and reliable sealing performance, make it the material of choice for demanding applications in aerospace, defense, medical, and high-reliability industrial sectors. The alloy's ability to maintain hermetic integrity under thermal cycling conditions while matching the expansion of hard glasses ensures long-term reliability in critical sealing applications. Compliance with international standards including **ASTM F15** guarantees consistent material quality and performance across all product forms and manufacturing processes.

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 2495 gallon liquid totes Special package is available on request.