Nickel Iron Alloys

NiFe 70/30 & NiFe 52/48 - Nickel Iron alloys have been developed to produce high-temperature coefficients of resistance (Positive Temperature Coefficient or PTC) in order to provide a ‘self-limiting’ heating wire.

When the temperature of the wire is around 250 °C the element resistance will have doubled and the power output will have halved.

Improved temperature control

Reduced energy consumption

Reduced power if overheating

High start-up power.

Nickel Iron Alloys are available in sizes down to 0.09 mm.

Physical and Mechanical Properties

UnitsNiFe 70/30NiFe 52/48
Maximum continuous operating temperature in air°C600600
°F11001100
Nominal composition%Ni 70Ni 52
Fe 30Fe 48
Density at 20°Cg/cm³8.458.2
lb/in³0.3050.296
Resistivity at 20°CµΩcm2137
Ω/cmf130220
Coefficient of thermal expansion,20 – 100°C1/K15 x 10^610 x 10^6
68 – 212°F1/°F8.3 x 10^65.6 x 10^6
Thermal conductivity at20°CW/mK1717
68°FBtu.in/ft².h.°F120120
Specific heat capacity at20°CkJ/kgK0.520.5
68°FBtu/lb°F0.120.12
Melting point (approx.)°C14301435
°F26102620
Magnetic properties (up to Curie point)MagneticMagnetic
Curie point°C610530
°F1130990
Tensile strength Rm(0.5 mm wire)N/mm²640610
lb/in²9300088000
Yield point Rp0.2(0.5 mm wire)N/mm²340340
lb/in²4900049000
Elongation at break (approx.) (0.5 mm wire)%3030

Temperature Dependant Factors

Reference temperature 20°C

Temp °C100150200250300350400450500
Temp °F212302392482572662752842932
70/30 Ni/Fe1.351.571.82.052.32.562.823.13.4
52/48 Ni/Fe1.331.531.731.932.132.322.492.642.77

The figures given in these tables represent nominal or typical values.

Information contained within this technical data sheet is based upon the general experience of Scott Precision Wire Ltd and is believed to be correct at the time of issue.

No warranty is given or is to be implied from the details above.

Customers are advised to carry out independent tests in order to determine the suitability of any Scott Precision Wire Ltd product for an application.