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Copper is not magnetic. This characteristic makes it ideal for applications where magnetic interference could affect performance or safety. Copper and copper-based alloys, including copper-nickel (cupronickel) and aluminium bronze, are widely used in marine, energy, and defence sectors for their combination of corrosion resistance, mechanical strength and low magnetic permeability.
In this article, we explain why copper is considered non-magnetic, how different types of magnetism occur in metals, and where alloys such as Hiduron 130 are best applied.
Magnetism in metals arises from the alignment of unpaired electrons in the atomic structure. In magnetic metals like iron or nickel, these unpaired electrons create magnetic fields that can align and reinforce each other.
Copper, however, has fully paired electrons. When copper atoms bond, their outer electrons form a shared cloud (a metallic bond) that does not support the formation of magnetic fields. As a result, copper displays diamagnetism, meaning it very weakly repels magnetic fields.
This makes copper, and most copper alloys, functionally non-magnetic in engineering applications.
Different metals respond to magnetic fields in different ways. These behaviours are grouped into three categories.
Ferromagnetic
Strongly attracted to magnets and retain magnetism even without an external field.
Examples: iron, nickel, cobalt
Paramagnetic
Weakly attracted to magnetic fields, but lose magnetism when the field is removed.
Examples: aluminium, platinum, magnesium
Diamagnetic
Repelled by magnetic fields and do not retain any magnetic properties.
Examples: copper, bismuth, lead
Copper is firmly in the diamagnetic category. This behaviour is critical in applications where even low-level magnetic interference must be avoided.
Most copper alloys, including bronzes and cupronickels, inherit copper’s non-magnetic characteristics. Even when alloyed with small amounts of magnetic elements, copper dominates the material’s magnetic behaviour.
One such alloy is Hiduron 130, a high-strength copper-nickel-silicon-iron alloy designed for demanding conditions.
Completely non-magnetic
Exceptional corrosion resistance in seawater
High strength and resistance to galling
Reliable performance after long periods of inactivity
Subsea connectors and couplings
Valve trim and pump shafts
Seawater piping
Systems where magnetic coupling must be avoided
Hiduron 130 is widely used in offshore, naval and chemical processing environments where non-magnetic materials are critical to system integrity.
Copper is also one of the best conductors of electricity. When exposed to a changing magnetic field, copper generates eddy currents, which are circular electrical currents that oppose the field. This behaviour is useful in applications involving electromagnetic shielding or damping.
Its ability to combine high conductivity with non-magnetic performance makes copper alloys ideal for use in sensitive components such as sensors, control systems and subsea electronics.
Langley Alloys supplies a range of non-magnetic copper-based alloys, including Hiduron 130, from stock in the UK and the USA. With deep product knowledge and sector-specific experience, we support customers across the marine, defence, energy and chemical processing industries.
To learn more or request a quote, contact our team today.
Worldwide Delivery Available
We can offer air, sea and road freight shipping options, with choice of packaging, to deliver to customers globally.
Inventory Management
Let us manage your total material requirements with call-off and consignment arrangements.
Up to 40 sizes per alloy available
More sizes equal less machining and a more cost-effective supply chain.
