Alloy 42,Low expansion 42 Alloy,UNS K94100,E FORU

### **Alloy 42 / Low Expansion 42 Alloy / UNS K94100** **Iron-Nickel Controlled Expansion Alloy for Electronic and Sealing Applications** --- #### **1. Overview** **Low Expansion 42 Alloy**, commonly referred to as **Alloy 42**, is an iron-nickel alloy engineered to provide a thermal expansion coefficient that closely matches those of various ceramic substrates, glasses, and semiconductor materials. This precise thermal matching capability makes it an essential material for electronic packaging applications where differential thermal expansion between components must be minimized to prevent stress-induced failures. The alloy demonstrates consistent performance across a broad temperature range, ensuring reliability in demanding electronic environments. --- #### **2. Chemical Composition (Weight %)** The typical chemical composition of Alloy 42 is outlined below. The balance is Iron (Fe). | Element | Content (%) | Key Function | | :--- | :--- | :--- | | **Iron (Fe)** | Balance | Forms the fundamental matrix of the alloy system. | | **Nickel (Ni)** | 41.0 - 42.5 | Critical for achieving the specific thermal expansion characteristics that match ceramic materials. | | **Manganese (Mn)** | 0.50 - 0.80 | Enhances manufacturability through improved hot workability and deoxidation. | | **Silicon (Si)** | 0.15 - 0.30 | Contributes to oxidation resistance and improves processing characteristics. | | **Carbon (C)** | 0.03 max | Strictly controlled to prevent outgassing and maintain sealing integrity. | | **Chromium (Cr)** | 0.15 max | Controlled trace element. | | **Cobalt (Co)** | 0.15 max | Controlled trace element. | | **Copper (Cu)** | 0.15 max | Controlled trace element. | | **Aluminum (Al)** | 0.05 max | Carefully regulated to ensure optimal surface properties for bonding. | | **Sulfur (S)** | 0.015 max | Minimized to prevent processing defects. | | **Phosphorus (P)** | 0.015 max | Controlled to maintain material ductility. | --- #### **3. Physical Properties** | Property | Value / Condition | | :--- | :--- | | **Density** | 8.11 g/cm³ (0.293 lb/in³) | | **Melting Point** | ~ 1420 °C (2588 °F) | | **Mean Coefficient of Thermal Expansion (CTE)** | 20 - 100°C (68 - 212°F): **4.6 x 10⁻⁶/°C** (2.6 x 10⁻⁶/°F)
20 - 200°C (68 - 392°F): **5.2 x 10⁻⁶/°C** (2.9 x 10⁻⁶/°F)
20 - 300°C (68 - 572°F): **5.8 x 10⁻⁶/°C** (3.2 x 10⁻⁶/°F) | | **Thermal Conductivity** | 14.5 W/m·K (100 Btu·in/hr·ft²·°F) at 20°C (68°F) | | **Specific Heat Capacity** | 515 J/kg·K (0.123 Btu/lb·°F) at 20°C (68°F) | | **Electrical Resistivity** | 0.68 μΩ·m at 20°C (68°F) | | **Modulus of Elasticity (Young's Modulus)** | 145 GPa (21.0 x 10⁶ psi) at 20°C (68°F) | | **Curie Temperature** | ~ 360 °C (680 °F) | | **Magnetic Properties** | Generally considered magnetic at room temperature | --- #### **4. Mechanical Properties (Typical for Annealed Condition)** | Property | Value at Room Temperature | | :--- | :--- | | **Tensile Strength** | 520 MPa (75 ksi) | | **Yield Strength (0.2% Offset)** | 350 MPa (51 ksi) | | **Elongation (in 50 mm / 2 in)** | 30% | | **Hardness (Rockwell B)** | 78 HRB | | **Shear Modulus** | 55 GPa (8.0 x 10⁶ psi) | --- #### **5. International Standards** Alloy 42 is specified in the following international standards: * **ASTM:** * **F30:** Iron-Nickel Sealing Alloys * **AMS:** * **AMS 7721:** Sheet, Strip, and Plate * **UNS:** K94100 * **ISO:** * **ISO 19960:** Iron-Nickel Low Expansion Alloys * **JIS:** * **JIS C 2531:** Iron-Nickel Alloy for Sealing Use * **MIL:** * **MIL-I-23011:** Insulating Compound, Electrical | --- #### **6. Product Applications** Alloy 42 serves critical functions in precision electronic and sealing applications: * **Microelectronics Packaging:** * Ceramic and glass seal packages * Integrated circuit lead frames * Semiconductor device headers * Power device packages * **Electronic Components:** * Transformer cores * Relay and switch components * Connector assemblies * Microwave package housings * **Automotive Electronics:** * Engine control modules * Sensor housings * Ignition system components * Power control units * **Telecommunications:** * Fiber optic components * RF connector packages * Base station electronics * Network infrastructure devices * **Industrial Controls:** * Instrumentation housings * Control system packages * Sensor encapsulation * Process control electronics --- #### **7. Key Characteristics & Advantages** * **Controlled Thermal Expansion:** Precisely matched CTE to alumina ceramics (∼7.0 x 10⁻⁶/°C) and certain glasses * **Excellent Sealing Performance:** Reliable hermetic and ceramic-to-metal seals * **Good Mechanical Properties:** Balanced strength and formability for electronic components * **Thermal Stability:** Consistent performance across operating temperature ranges * **Manufacturing Versatility:** Suitable for stamping, etching, and forming processes * **Cost-Effective Solution:** Provides reliable performance at competitive cost * **Proven Reliability:** Extensive application history in demanding environments * **Consistent Quality:** Tight compositional control ensures reproducible performance --- **Disclaimer:** *The values provided are typical and for informational purposes only. For critical applications, always consult the official material data sheets from the supplier and relevant design codes. Proper processing and heat treatment are essential for achieving optimal performance in specific applications.*

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 1686 gallon liquid totes Special package is available on request.