# Alloy 48 UNS K94800: Properties and Applications
## Introduction to Alloy 48 UNS K94800
Alloy 48, also known by its UNS designation K94800, is a nickel-iron alloy with controlled thermal expansion characteristics. This specialized material finds applications in industries where precise dimensional stability across temperature ranges is critical.
## Chemical Composition
The composition of Alloy 48 UNS K94800 typically includes:
– Nickel: 47.5-48.5%
– Iron: Balance
– Manganese: ≤0.30%
– Silicon: ≤0.30%
– Carbon: ≤0.10%
– Sulfur: ≤0.020%
This carefully balanced composition gives Alloy 48 its unique thermal expansion properties.
## Physical Properties
Alloy 48 exhibits several notable physical properties:
– Density: 8.25 g/cm³
– Melting Range: 1425-1475°C (2600-2690°F)
– Curie Temperature: Approximately 400°C (750°F)
– Electrical Resistivity: 49 μΩ·cm at 20°C
– Thermal Conductivity: 11.7 W/m·K at 20°C
## Mechanical Properties
The mechanical characteristics of Alloy 48 include:
Keyword: Alloy 48 UNS K94800
– Tensile Strength: 517 MPa (75 ksi)
– Yield Strength: 276 MPa (40 ksi)
– Elongation: 30% in 2 inches
– Hardness: Rockwell B 80
– Modulus of Elasticity: 148 GPa (21.5 x 10⁶ psi)
## Thermal Expansion Characteristics
Alloy 48 is particularly valued for its controlled thermal expansion properties:
– Coefficient of Thermal Expansion (20-300°C): 8.9 x 10⁻⁶/°C
– The alloy maintains a nearly constant coefficient of thermal expansion over a wide temperature range
– Exhibits excellent dimensional stability during temperature fluctuations
## Key Applications
Due to its unique properties, Alloy 48 finds use in various demanding applications:
### Electronics Industry
– Lead frames for semiconductor devices
– Glass-to-metal seals in electronic components
– Thermocompression bonding applications
### Aerospace Applications
– Precision instruments requiring dimensional stability
– Satellite components exposed to temperature extremes
– Guidance system components
### Industrial Uses
– Bimetal thermostats
– Temperature-sensitive measuring devices
– Precision optical equipment
– Laser components
## Fabrication and Processing
Alloy 48 can be processed using standard techniques:
– Machining: Can be machined using standard methods, though it work-hardens
– Welding: Can be welded using TIG or resistance welding methods
– Forming: Can be cold worked, though annealing may be required for severe forming operations
– Heat Treatment: Typically supplied in annealed condition
## Advantages Over Other Materials
Alloy 48 offers several advantages compared to alternative materials:
– Better thermal expansion match to certain glasses and ceramics than other nickel-iron alloys
– Maintains properties over a wider temperature range than many alternatives
– Good corrosion resistance in many environments
– Excellent fatigue resistance in thermal cycling applications
## Comparison with Similar Alloys
While similar to other nickel-iron alloys, Alloy 48 has distinct characteristics:
– Lower nickel content than Alloy 42 (Ni 42%)
– Different thermal expansion curve compared to Alloy 52 (Ni 52%)
– More cost-effective than some higher-nickel alternatives while maintaining performance
## Conclusion
Alloy 48 UNS K94800 serves as a critical material in applications requiring precise control of thermal expansion characteristics. Its unique combination of properties makes it indispensable in electronics, aerospace, and precision instrumentation industries. As technology advances and demands for dimensional stability increase, Alloy 48 continues to prove its value in specialized engineering applications.
