Alloy 42 (UNS K94100 / Nilo 42) – Technical Data & Availability

Alloy 42 is a nickel-iron controlled-expansion alloy (42% Ni, balance Fe) engineered specifically for glass and ceramic sealing applications. Its primary function is to match the thermal expansion characteristics of certain soft glasses and ceramics, creating hermetic seals that remain reliable through thermal cycling.

1. Operating Limits & Critical Selection Criteria

This alloy is selected almost exclusively for its thermal expansion behavior rather than corrosion resistance or strength.

• Effective Temperature Range: Designed to maintain a consistently low coefficient of thermal expansion (CTE) from room temperature up to approximately 300°C (570°F) .

• Material Matching: It is specifically formulated to match the expansion rates of alumina ceramics and borosilicate-type glasses. Using it outside this temperature window or with mismatched sealing materials risks seal failure due to stress at the interface.

• Magnetic Properties: The alloy remains magnetic throughout its service range.

2. Manufacturing Data & Processing Requirements

Unlike structural alloys, Alloy 42 requires precise heat treatment to achieve the dimensional stability required for sealing.

• Chemical Composition (Typical)

  Element	Content (%)
  Nickel (Ni)	41.5 - 42.5
  Iron (Fe)	Balance
  Others	≤ 1.0

• Mechanical Properties

  Property	Metric	Imperial
  Tensile Strength	490 MPa	71 ksi
  Yield Strength	250 MPa	36.3 ksi
  Modulus of Elasticity	150 GPa	21,755 ksi

• Physical Properties

  Property	Metric	Imperial
  Density	8.11 g/cm³	0.293 lb/in³

• Fabrication & Heat Treatment

  • Annealing: Required to achieve proper softness and controlled expansion characteristics. Perform at 850 – 1000°C (1560 – 1830°F) in a protective atmosphere.

  • Cold Working: Generally not recommended for final components. Cold working introduces internal stresses that distort the coefficient of thermal expansion, leading to seal failure. If cold forming is necessary, a full anneal must follow.

  • Surface Quality: For glass sealing, surfaces must be clean and free of contaminants that could cause bubble formation or poor wetting.

3. Applications

Alloy 42 is specified wherever a metal must pass through glass or ceramic while maintaining a vacuum or pressure tight seal:

• Semiconductor industry: Lead frames and IC substrates.

• Electrical components: Glass-to-metal seals in fluorescent lights, relays, and television tubes.

• Thermostats: As the low-expansion side in bimetal strips and thermostat rods.

• Hermetic connectors and feedthroughs.

4. Available Product Forms & Supply

For engineers sourcing precision expansion alloys, ZYTC Alloy supplies certified Alloy 42 (Nilo 42) in all standard mill forms. Stock is available for immediate processing or shipment.

• Sheet & Plate

• Bar & Rod

• Wire (round, flat)

• Strip (precision slit)

• Pipe & Tube

• Forgings

All material is supplied with traceable certification, suitable for sensitive electronic and sealing applications.

Contact Us：

Email:daisy@zytcsteel.com

WhatsApp/WeChat: +86 17335753350