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Alloy 42

City Special Metals - UK-based Alloy 42 Suppliers

Alloy 42 is an iron-nickel alloy, consisting of 42% nickel. This controlled expansion alloy has low thermal expansion characteristics over a range of temperatures and has been developed over time with ceramics in mind.

Do you have applications Alloy 42 would be suited to? Speak to us today and receive expert advice from a leading UK speciality metals stockist. Have any other alloy requirements? See a list of our specialist alloys here. If you can't find what you're looking for there, click the following link for other speciality alloys we stock.

Alloy 42 Stockist Range

Product Form Range From Range To
Alloy 42 Round Bar icon

Alloy 42 Round Bar

4mm 127mm
Alloy 42 Sheet & Coil icon

Alloy 42 Sheet & Coil

0.15 3.2mm

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    Beneficial Properties

    • Shock-resistant Their coefficient thermal expansion makes the seal resistant to shock and cracking
    • Ability to withstand extreme temperatures Low thermal expansion over a range of temperatures
    • Flexibility Good workability, weldability and easy to machine

    Markets & Applications

    • Electronic components such as: semiconductor packages, tubes, CRT electron guns, automotive & industrial lamps
    • Lead frames
    • Thermostat bimetal
    Call City Special Metals +44 1268 774 261

    Alloy 42 Composition

    Mechanical Properties

    Metallurgical Condition Annealed, Descaled
    Yield Strength KSI (MPa) 36 (248)
    Tensile Strength KSI (MPa) 71 (490)
    Hardness HB
    Elongation 50mm >40

    Technical Specifications

    ATSM UNS Werkstoff
    F30 K94100 1.3917


    Nickel Ni 42
    Iron Fe Balance

    Physical Properties

    Co Efficient of Thermal Expansion
    30-300°C 10-6/°C 4.6
    30-350°C 10-6/°C 5.05
    30-400°C 10-6/°C 6.12
    Density g/cm³ 8.15
    Curie Temp °F 626
    °C 330
    Melting Point °F 2597
    °C 1425
    Modulus of Elasticity at 20°C MPa 148
    Specific Heat J/g- °C 0.50
    Thermal Conductivity at 20°C J/cm.s.°C 12.5
    Resistivity at 0°C Μ 63
    Poisson's coefficient

    Alloy 42 Properties & Information

    Low Thermal Expansion alloys are perfectly suited for use in glass and ceramic seals, providing metallic feed‐throughs from interior to exterior components. Another great use of Alloy 42 is within electrical components – here are a few reasons why.

    Alloy 42, and similarly Kovar, should always be manufactured according to exact requirements. In ceramics, a low coefficient of thermal expansion (CTE) of must be matched by the feed‐through metal.

    City Special Metals ensure that every alloy is manufactured to provide the ideal coefficient.

    Our alloys are reliable and provide perfect hermetically sealed connections. This particular alloy has few limitations in its use and is ideal for use in annealed plates, sheets and rods.

    Call City Special Metals +44 1268 774 261

    We offer a bespoke service so, if you don’t see the size or form that you require, contact us either by phone, email or our contact form below, and we will provide a solution to your requirements.

    The History of Alloy 42

    Alloy 42 is widely used for military applications. It's hermeticity and attachability to low‐CTE die to low‐CTE lead frames have been cited as 2 main advantages of using Alloy 42. However, when placed into plastic components Alloy 42 has proven to provide disastrous results.

    City Special Metals understands that mismatching can take place with Alloy 42, whether that be a result of surface mount (SM) solder joints connecting materials with different CTEs, or when solder bonds have CTEs that differ from the CTE of solder. We'll work alongside you to ensure that the desired result is found, with little-to-no SM solder joint failures.

    Alloy 42 and Kovar not only cause significant global and local thermal expansion mismatches, but are inherently more difficult to solder because of the low solubility of nickel and iron, the main constituents of these alloys. Pull tests of solder joints show that, under the best of circumstances, a solder joint that includes an Alloy 42 or Kovar surface is only half as strong as one made to copper surfaces.

    Alloy 42 is also known by the following trade names;

    • N42®
    • Nilo 42®
    • Dilaton 41®
    • Pernifer 42®
    • Glass Seal 42®