NiFe Alloy 42

Short Introduction:

  • NiFe Alloy 42  is used for glass-to-metal sealing of components that are enclosed in a glass envelope, such as lamps and electron tubes.


    NiFe Alloy 42

    NiFe Alloy 42/4j42 iron-nickel constant expansion alloy is a series of constant expansion alloys that can be matched with soft glass and ceramics with different expansion coefficients in a given temperature range by adjusting the content of nickel bai. Its expansion coefficient and Curie point increase with the increase of nickel content. increase. This alloy is a widely used sealing structure material in the electric vacuum industry.

    NiFe Alloy 42/4J42 application overview and special requirements:

    NiFe Alloy 42/4J42 is a typical grade of glass-sealed alloy, with stable performance after long-term use in aviation factories.

    NiFe Alloy 42/4J42 alloy is mainly used for sealing with soft glass, ceramics, etc., to make leads, frames and sealing plugs for electronic tubes, transistors and integrated circuits.

    In the application, the selected sealing material should match the expansion coefficient of the alloy. The grain size should be controlled during heat treatment to ensure that the material has good deep drawing properties. When using forged and rolled materials, the air tightness of the materials should be strictly inspected.

    Ni Fe Alloy42 material grades and equivalents:

    Trademark GB AISI/ASTM UNS W.Nr BS AFNOR IMPHY VAC Telcan USA Magnetics Japan
    Alloy 42 4J42 USA(ASTM)Glass sealing 42 / Uniseal 42 UNS K94100 WS 1.3917 Ni42 Germany:  Vacodil 42 / Nilo 42 Dumet42 / DIN 17745 AFNOR NF A54-301 Vacodil 42 Nilo 42 Glass sealing 42 D

    Chemical composition:











    Alloy 42

    Max 0.05

    Max 0.020

    Max 0.020

    Max 0.80

    Max 0.30

    Max 0.10

    Max 1.0



    NiFe Alloy42/4j42 Physical and chemical properties:

    NiFe Alloy42/4j42 melting temperature: 1430℃.

                                            Thermal conductivity of 4J42: λ=14.6W/(m·℃).

    NiFe Alloy42/4j42 specific heat capacity: 502J/(kg•℃).

    NiFe Alloy42/4j42 density: ρ=8.12g/cm3.

    NiFe Alloy42/4j42 electrical properties: resistivity ρ=0.61μΩ·m.

    NiFe Alloy42/4J42 Curie point: Tc=360℃.

    Mechanical properties:


    Tensile Strength N/mm²



    Alloy 42



    Alloy42/4J42 surface treatment process:

    Before heat treatment, welding or glass sealing, the dirt and grease on the metal surface must be removed. When the oxide layer is severe, sandblasting or soaking in molten alkali solution can be used, and then pickling. Slightly oxidized scale can be pickled with 25% hydrochloric acid solution at 70℃.

    Alloy42/4J42 cutting and grinding performance:

    The cutting characteristics of this alloy are similar to austenitic stainless steel. High-speed steel or cemented carbide tools are used for processing, low-speed cutting, and coolant can be used when cutting. Good grinding performance.

    Main specifications of Alloy42/4J42:

    • seamless pipe

    • steel plate

    • round steel

    • forgings

    • flange

    • ring

    • welded pipe

    • steel strip

    • straight bar

    • wire and supporting welding materials

    • round cake

    • flat steel

    • hexagon bar

    • size head

    • elbow

    • tee

    • machined parts

    • bolts and nuts

    • fasteners