Nilo 50 (also known as 4J50, FeNi50, UNS K94700, Nilo51, 50H, Vacovit 500) is a high-performance iron-nickel controlled expansion precision alloy, engineered for exceptional dimensional stability and thermal expansion matching with soft glass, alumina ceramics, and other sealing materials. As a core structural material in the electro-vacuum and precision electronics industries, it delivers consistent performance across a wide temperature range, making it the material of choice for applications requiring air-tight, reliable hermetic sealing.
Nilo 50 (UNS K94700) Chemical Composition (GB/T 37797 / YB/T 5235-1993 Standards)
The precise control of nickel content is the cornerstone of Nilo 50's unique expansion characteristics. Strict composition consistency ensures reliable performance in critical applications:
Element | Content Range (%) |
Ni | 49.5 ~ 50.5 |
Fe | Balance |
C | ≤ 0.05 |
Si | ≤ 0.30 |
Mn | ≤ 0.80 |
P | ≤ 0.020 |
S | ≤ 0.020 |
Al | ≤ 0.10 |
Co | ≤ 1.0 |
Nilo 50 (UNS K94700) Core Performance Parameters
1. Physical Properties
Performance Indicator | Parameter Value | Practical Description |
Density | 8.21 g/cm³ | Standard at 20℃, ideal for precision component design |
Coefficient of Thermal Expansion (20~100℃) | 4.9 ~ 5.3 × 10⁻⁶/℃ | Exceptional match with soft glass, minimal sealing stress |
Coefficient of Thermal Expansion (20~400℃) | ~9.8 × 10⁻⁶/℃ | Stable expansion profile for consistent performance |
Curie Temperature | Approx. 515℃ | Higher than lower nickel alloys, extended operating range |
Resistivity | Approx. 0.50 μΩ·m | Standard at 20℃, suitable for electronic conductive applications |
Thermal Conductivity | 16.3 W/(m·K) | Ensures uniform heat distribution in thermal management scenarios |
Melting Point | 1430℃ | Suitable for high-temperature sealing and processing |
2. Mechanical Properties
Performance Indicator | Typical Value | Application Reference |
Tensile Strength | ≥ 450 MPa | Meets structural strength requirements for precision components |
Yield Strength | ≥ 220 MPa | Ensures dimensional stability after forming and machining |
Elongation | ≥ 30% | Facilitates complex cold forming, deep drawing, and stamping |
Hardness (HB) | ≤ 200 | Excellent machinability with standard tooling |
Elastic Modulus | 162 GPa | Ideal for precision instrument components requiring minimal deflection |
3. Nilo 50 (UNS K94700) Core Advantages
• Superior Expansion Matching: Engineered for precise coefficient matching with soft glass and alumina ceramics, virtually eliminating interface stress during sealing and preventing cracking failures
• Exceptional Dimensional Stability: Single-phase austenitic microstructure maintains consistent dimensions across wide temperature fluctuations
• Excellent Processing Flexibility: Outstanding cold/hot workability, weldability, and machinability, supporting complex component geometries
• Robust Corrosion Resistance: Performs reliably in atmospheric, fresh water, and mild corrosive environments, suitable for long-term service in electronic packaging
• Magnetic Properties: Controlled magnetic characteristics for applications requiring specific permeability profiles
Nilo 50 (UNS K94700) Processing & Heat Treatment Guidelines
1. Processing Capabilities
• Forming: Excellent cold rolling, deep drawing, and stamping performance; maintains formability after annealing
• Welding: Compatible with arc welding, resistance welding, and brazing; weld properties match base material without performance degradation
• Machining: Similar to austenitic stainless steels; high surface finish achievable with carbide tools at moderate speeds
• Brazing: Ideal for glass-to-metal sealing applications with compatible brazing alloys and temperature profiles
2. Recommended Heat Treatment
• Soft Annealing: 850\900℃ for 1\2 hours, air or furnace cooling; optimizes ductility for subsequent forming operations
• Stabilization Annealing: 300\500℃ for 2\4 hours; enhances dimensional stability for precision applications
• Pre-Sealing Preparation: Bright annealing or pickling to remove surface contaminants, ensuring optimal sealing integrity
Nilo 50 (UNS K94700) Key Application Areas
1. Electronic Packaging & Electro-Vacuum Devices (Core Application)
• Leads, frames, and hermetic plugs for electron tubes, transistors, and integrated circuits
• Semiconductor lead frames requiring glass/ceramic sealing
• Hermetic components for vacuum switches, relays, and sensor assemblies
• High-reliability connectors and terminal posts
2. Precision Instruments & Measurement Equipment
• Precision resistance and potentiometer skeletons
• Thermostats, thermal bimetallic strips, and temperature controller components
• High-precision length standards and measuring instruments
• Precision impedance film discs and filter components
3. Aerospace & Advanced Electronics
• Satellite and spacecraft precision components requiring thermal stability
• Aerospace sensor housings and hermetic packaging
• Optical instrument components preventing thermal deformation
• High-reliability avionics connectors and terminals
4. Medical & Automotive Electronics
• Medical device sensor components requiring long-term stability
• Automotive electronics connectors and sealed assemblies
• Pressure sensors and environmental monitoring components
• Hermetically sealed automotive sensor housings
Nilo 50 (UNS K94700) Alloy Summary
Nilo 50 (4J50, FeNi50, UNS K94700) represents the pinnacle of iron-nickel controlled expansion alloys, offering unmatched thermal expansion matching with soft glass and ceramics alongside exceptional dimensional stability and processing versatility. As a critical material in the electro-vacuum and precision electronics industries, it enables reliable hermetic sealing and long-term performance in the most demanding applications.
Our state-of-the-art manufacturing facilities ensure strict compliance with GB/T 37797 and YB/T 5235-1993 standards, with rigorous quality control throughout the production process. We provide comprehensive technical support, customized solutions, and reliable supply chain management to meet your specific project requirements.
Contact us today for samples, competitive quotes, or customized Nilo 50 solutions tailored to your application needs. Our team of experts is ready to assist with material selection, design optimization, and production planning to ensure project success.
