Constantan® Foil

Constantan® Foil is a precision cold-rolled form of the copper–nickel alloy known for its exceptional resistance stability over a wide temperature range and very low thermal EMF when paired with copper. Comprising approximately 55% copper and 45% nickel, it offers a unique balance of corrosion resistance, mechanical strength, and predictable resistivity, making it highly valued in sensing and measurement technologies. Its foil form is integral to strain gauges, precision resistors, and thermal compensation devices across aerospace, electronics, and materials testing sectors. Specific applications include pressure sensor diaphragms, Wheatstone bridge strain transducers, and resistance elements in precision instrumentation. The foil’s predictable fatigue-related resistance changes also enable its use in fatigue life gauges for structural monitoring. Advances in heat treatment and bonding techniques have enhanced its adhesion to substrates, mechanical durability, and electrical stability, enabling its integration into high-reliability, miniaturized sensor platforms. Constantan® Foil remains a cornerstone material in research and industrial environments requiring high-accuracy electrical measurement and stability under variable conditions.

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Tolerance

Properties

Reference & Citations

each

Tolerances

Foil

Thickness	<0.01mm	±25%
Thickness	0.01mm - 0.05mm	±25%
Thickness	>0.05mm	±10%

Material Properties for Alloys

Mechanical Properties

Element	Value
Hardness - Brinell	100-300
Elongation at break( % )	45
Modulus of elasticity( GPa )	162
Izod impact strength( J m⁻¹ )	107
Tensile strength( MPa )	400-590

Electrical Properties

Element	Value
Electrical resistivity( µOhmcm )	52
Temperature coefficient( K⁻¹ )	0.00002+/-

Thermal Properties

Element	Value
Maximum use temperature in air( C )	500
Melting point( C )	1225-1300
Thermal conductivity( W m⁻¹ K⁻¹ )	19.5@23°C
Coefficient of thermal expansion( x10⁻⁶ K⁻¹ )	14.9@20-100°C