Kovar,Alloy K ,UNS K94610,E FORU

British Specs:，American Specs: ASTM F15 ASTM F26 AMS 7726 Wire AMS 7727 Bar and Forgings AMS 7728 Sheet, Strip and Plate MIL-I-23011 Class 1，German Specs:WS 1.3981,AFNOR NF A54-301

**Technical Data Sheet: Kovar / Alloy K / UNS K94610** **1.0 Product Overview** Kovar (Alloy K), standardized as UNS K94610, is a nickel-cobalt ferrous alloy specially designed to match the thermal expansion characteristics of hard glass and ceramic materials. This controlled expansion alloy exhibits a thermal expansion coefficient similar to borosilicate glass over a wide temperature range, making it ideal for creating reliable hermetic seals in electronic and aerospace applications. **2.0 Chemical Composition** | Element | Content (%) | Primary Function | |---------|-------------|------------------| | Fe | Balance | Base Element | | Ni | 28.5-29.5 | Thermal Expansion Control | | Co | 16.8-17.8 | Thermal Expansion Matching | | Mn | 0.20-0.50 | Deoxidizer | | Si | 0.10-0.30 | Deoxidizer | | Al | 0.05 max | Deoxidizer | | Mg | 0.05 max | Deoxidizer | | C | 0.02 max | Minimize carbide formation | | P | 0.02 max | - | | S | 0.02 max | - | *Note: The precise balance of nickel and cobalt is critical for maintaining the alloy's unique thermal expansion properties.* **3.0 Physical Properties** | Property | Metric Value | Imperial Value | Condition | |----------|--------------|----------------|-----------| | Density | 8.36 g/cm³ | 0.302 lb/in³ | Room Temperature | | Melting Point | 1450°C | 2640°F | - | | Thermal Conductivity | 17.3 W/m·K | 120 Btu·in/(hr·ft²·°F) | 20°C | | Mean Coefficient of Thermal Expansion | 4.9-5.5 × 10⁻⁶/°C | 2.7-3.1 × 10⁻⁶/°F | 20-400°C | | Electrical Resistivity | 0.49 μΩ·m | 19.0 μΩ·in | 20°C | | Modulus of Elasticity | 138 GPa | 20.0 × 10⁶ psi | Room Temperature | | Curie Temperature | 435°C | 815°F | - | **4.0 Mechanical Properties** **4.1 Typical Room Temperature Properties (Annealed)** - Tensile Strength: 517-586 MPa (75-85 ksi) - Yield Strength (0.2% Offset): 345-414 MPa (50-60 ksi) - Elongation: 25-35% - Hardness: 65-80 HRB - Modulus of Elasticity: 138 GPa (20.0 × 10⁶ psi) **4.2 Thermal Expansion Characteristics** - Matches borosilicate glass (Pyrex) - Low thermal expansion below Curie temperature - Stable dimensional characteristics - Minimal thermal stress during sealing **5.0 Product Specifications** **5.1 Available Forms** - Sheet and Strip: 0.05 mm to 6.0 mm thickness - Rod and Bar: 1.0 mm to 150 mm diameter - Wire: 0.1 mm to 12.0 mm diameter - Custom forgings and fabricated parts **5.2 Surface Conditions** - Annealed and pickled - Cold rolled - Ground and polished - Special coated finishes **6.0 Manufacturing Processes** **6.1 Production Methods** - Electric arc or induction melting - Hot and cold working - Annealing in controlled atmosphere - Precision rolling and drawing **6.2 Quality Control** - Chemical composition verification - Thermal expansion testing - Mechanical property testing - Surface quality inspection **7.0 Heat Treatment** **7.1 Standard Annealing** - Temperature: 850-900°C (1560-1650°F) - Atmosphere: Hydrogen or vacuum recommended - Time: 15-30 minutes per 25 mm thickness - Cooling: Rapid cooling to 400°C, then air cool **7.2 Stress Relieving** - Temperature: 425-540°C (800-1000°F) - Time: 30-60 minutes - Atmosphere: Air or protective atmosphere **8.0 Product Applications** **8.1 Electronics & Semiconductor** - Glass-to-metal seals in transistors - Diode and integrated circuit packages - Microwave tube components - Laser and optoelectronic housings - Ceramic-to-metal seals **8.2 Aerospace & Defense** - Aerospace electronic packages - Satellite communication components - Radar system housings - Military electronic enclosures - Navigation system components **8.3 Industrial Applications** - Power semiconductor devices - High-voltage feedthroughs - X-ray tube components - Vacuum interrupter envelopes - Hermetic connector assemblies **9.0 International Standards & Specifications** | Standard Organization | Standard Number | Description | |----------------------|-----------------|-------------| | ASTM | F15 | Standard Specification for Iron-Nickel-Cobalt Sealing Alloy | | UNS | K94610 | Unified Numbering System | | MIL | MIL-I-23011 | Sealing Alloys | | DIN | 1.3981 | German Material Number | | JIS | H 4551 | Japanese Industrial Standard | | GB | GB/T 15018 | Chinese Standard | **10.0 Fabrication Characteristics** **10.1 Machining** - Good machinability in annealed condition - Use sharp, positive rake tools - Recommended cutting speed: 30-45 m/min - Adequate cooling and lubrication required - Work hardening requires careful handling **10.2 Welding & Joining** - Excellent weldability using GTAW and GMAW - Suitable for resistance welding - Can be brazed with silver-based alloys - Requires clean surfaces for optimal results **11.0 Glass Sealing Performance** **11.1 Sealing Characteristics** - Excellent compatibility with borosilicate glass - Forms strong, hermetic bonds - Minimal thermal stress during cooling - Reliable long-term performance - Good oxidation resistance during sealing **11.2 Surface Preparation** - Cleaning and degreasing essential - Pre-oxidation for optimal glass wetting - Controlled oxide layer formation - Surface activation before sealing **12.0 Quality Assurance** **12.1 Testing Requirements** - Chemical composition analysis - Thermal expansion coefficient verification - Mechanical property testing - Metallographic examination - Surface quality inspection **12.2 Certification** - Mill Test Certificates per EN 10204 3.1 - Full material traceability - Special testing for critical applications - Compliance with customer specifications Kovar (Alloy K, UNS K94610) remains the industry standard for applications requiring precise thermal expansion matching with glass and ceramic materials. Its unique combination of thermal, mechanical, and sealing properties makes it indispensable for creating reliable hermetic seals in electronic, aerospace, and specialized industrial applications where long-term reliability and performance are critical.

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 2352 gallon liquid totes Special package is available on request.