Invar 42 (4J42 / Nilo 42 /Alloy42/ UNS K94100) Iron-Nickel Controlled Expansion Alloy
Invar 42 Iron-Nickel Controlled Expansion Alloy
4J42 (Invar 42) is an iron-nickel controlled expansion alloy. Its core characteristic is a stable and controllable coefficient of thermal expansion within a specific temperature range. It is primarily used in the electric vacuum industry for matched sealing with soft glass or ceramics.
Material Classification
Classification: Controlled expansion alloy (sealing alloy), belonging to the iron-nickel alloy system.
Naming Origin: In the Chinese grade “4J42,” “4″ represents expansion alloy, “J” is the Pinyin initial for “precision,” and “42″ indicates a nickel content of approximately 42%.
Corresponding International Grades: UNS K94100, Alloy 42, Nilo 42 (USA); W.Nr. 1.3917 (Germany); Nilo 42 (UK); YEF42 (Japan); N42 (France).
Key Characteristics & Applications
Characteristics: It exhibits a low and relatively constant coefficient of thermal expansion from room temperature up to approximately 300-450°C. This matches the expansion characteristics of soft glass and 95% alumina ceramic, enabling hermetic sealing.
Main Applications: Electron tubes, transistors, integrated circuit lead frames, semiconductor packaging, temperature control rods, automotive and industrial lamps, glass-to-metal and ceramic-to-metal seals.
