Bronze is an alloy made from copper and tin. Throughout human history, it has been an important material that has greatly contributed to the advancement of civilizations. Today bronze is used in numerous applications, from the automotive industry to architecture, agriculture, and more. One particularly interesting aspect of this metal is its magnetic behavior.

Before deciding to implement bronze in any application, understanding whether or not it is magnetic is an important step. As one of North America’s leading bronze suppliers, Sequoia Brass & Copper can help you with everything you need to know about this valuable metal alloy. In this blog, we’ll explore the magnetic properties of bronze and discuss how its alloying elements influence its overall magnetic behavior.

Bronze Composition

As a copper and tin alloy, bronze is typically composed of around 88% copper and 12% tin. Both of these metals feature unique atomic structures and magnetic properties that influence bronze’s characteristics. In its pure form, copper features no magnetic properties, while tin is lightly attracted to magnetic fields.

Magnetic Properties of Copper

Magnetism is caused by the motion of electrons spinning around an atom’s nucleus. When equal numbers of electrons spin in opposite directions, they are not attracted to a magnetic field. When they spin in the same direction, however, a magnetic field is produced. Copper has a face-centered cubic crystal structure, and features a single valence electron in its outer shell. Due to this unpaired electron, copper exhibits some weak diamagnetic properties.

A diamagnetic material is one that creates a weak magnetic field in opposition to externally applied magnetic fields. While the diamagnetic effect of copper is weak, the metal still demonstrates an inherent aversion to magnetic forces.

Magnetic Properties of Tin

Tin has a body-centered tetragonal crystal structure and, unlike copper, contains two free valence electrons. These electrons cause tin to be weakly paramagnetic. Paramagnetism is caused by a material’s multiple unpaired electrons that are weakly attracted to an externally applied magnetic field.

Similar to copper, tin’s paramagnetic properties are not particularly strong, but still present. When tin and copper are combined into an alloy, their unpaired electrons pair up, creating a non-magnetic material.

Bronze’s Magnetic Behavior

When we have a basic understanding of the metals bronze is made up of, it becomes easier to predict how this material will behave. Bronze’s magnetic behavior is most significantly influenced by the proportion of copper and tin that are used to create it. Since copper makes up the largest proportion of bronze, it contributes its diamagnetic behavior to the alloy.

While tin is a paramagnetic material, it is not dominant enough to affect bronze’s overall magnetism. As a result, bronze’s magnetic behavior is close to diamagnetic, due to its copper dominance. This means that bronze slightly repels a magnetic field, although the effect is significantly weaker than that of pure copper, due to the influence of tin.

The Influence of Impurities in Bronze

While bronze is primarily composed of tin and copper, both historical and modern bronze alloys can contain trace amounts of impurities. Due to variations in ore sources or manufacturing techniques, other metals, non-metals, and metalloids are sometimes found in bronze, such as:

  • Phosphorous
  • Silicon
  • Aluminum
  • Manganese
  • Nickel

In some cases, these impurities can impact bronze’s magnetic behavior. Impurities that introduce ferrimagnetic or ferromagnetic behavior can make bronze more responsive to magnetic fields. Depending on the type and amount of materials added to bronze, various useful properties can be achieved, such as enhanced machinability or ductility.

When materials like aluminum or manganese are added, bronze becomes weakly magnetic, since both aluminum and manganese are paramagnetic materials. For this reason, it’s important to understand which alloying metals are found in bronze before selecting a certain type for an application.

Learn More About Bronze with Sequoia Brass & Copper

Since bronze is primarily made up of copper, which is diamagnetic, bronze is not magnetic. However, it’s possible for other elements to be added in quantities that subtly affect bronze’s magnetic behavior. With its diverse range of end-use applications, bronze products are a necessity for many industries.

Sequoia Brass & Copper specializes in supplying high-quality alloy bronze metals at competitive prices. All of our bronze products are cut to order according to your specifications. To learn more, visit our bronze page to review our product offerings or request a quote to get started on your next project.

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