Copper and alloys primarily based upon copper are considered non-magnetic. This is because of its atomic structure.
In nature, magnetism in metals is a result of an uneven distribution of electrons within the atomic structure of the magnetic material — electrons flow from one ‘shell to the next and free to spin. This free flow of electrons creates magnetic dipoles. While copper atoms do have a single electron in their valence (or outermost) shell, when multiple copper atoms come together, these valence electrons get sent into a cloud which forms metallic bonds between the copper atoms. This makes copper diamagnetic — it repels magnetic fields.
This is an important physical property of Hiduron 130, a high-strength copper-nickel alloy. Like all cupronickels, Hiduron 130 is used in subsea applications such as connectors and couplings, as well as valve trim and seawater piping. As a copper-based alloy, it is resistant to fouling and galling, making it suitable for applications which see long periods of inactivity but which then are required to operate without sticking. Therefore, avoiding the potential influence of magnetic coupling is supportive of such applications.
If you have a sufficiently strong magnetic field, all matter is magnetic — the pull being so strong that the usual electron requirements are not necessary for magnetic dipoles to form. However, this is not the case for every metal.
Ferromagnetic Metals are those metals with space on their valence shells for electrons to move about. These metals are freely attracted to magnets, even with the absence of external magnetic fields acting upon them. Examples of Ferromagnetic Metals include Iron, Cobalt, and Neodymium.
Paramagnetic Metals, such as platinum, aluminum and uranium, have a much weaker attraction to magnets than ferromagnets and don’t maintain their magnetic properties in the absence of a magnetic field.
Diamagnetic Metals are those metals which repel magnetic fields. This is because of a change in the orbital spin of electrons due to an applied external magnetic field. When the magnetic field is taken away, the metal loses its diamagnetic properties. Copper, Bismuth, and Lead are examples of Diamagnetic Metals.
As two aspects of the electromagnetic force, magnetism and electricity are quite similar. A moving electric current generates a magnetic field, for example, and when a magnet moves near copper or other metals, it sets up electrical eddy currents.
If you would like to know more about copper-based alloys, please contact Langley Alloys today.