Have you ever wondered can’t a magnet be put back together after it breaks？In fact, it’s not absolute. We need to classify and analyze specific situations.

In daily life scenarios, the vast majority of magnets we come across belong to the category of artificial magnets. Common types of magnets such as ferrite magnets, neodymium magnets and samarium-cobalt magnets are mostly manufactured through the powder metallurgy process at present.

The manufacturing process of powder metallurgy has unique advantages, which can enable magnets to obtain more excellent magnetic performance. For instance, when manufacturing neodymium-iron-boron (NdFeB) magnets, the powders of elements such as neodymium (Nd), iron (Fe) and boron (B) will be mixed first according to the optimal atomic ratio, and then pressed and sintered for shaping. This precise control of the composition avoids local differences in magnetic performance caused by uneven composition, making the overall magnetic performance of the magnets more stable and excellent.

However, from the perspective of microstructure, the powder metallurgy process also has some limitations. During the sintering stage, even if the process flow is optimized to the greatest extent, due to multiple factors such as the characteristics of powder particles and the limitations of sintering conditions, it is often inevitable that many tiny pores will be generated inside the material, which reduces the overall strength of the magnet. Therefore, when the magnet accidentally falls to the ground or encounters external forces such as collisions and impacts during daily use, it is very likely that the magnet will break and be damaged.

So, why is it that certain magnets are capable of being rejoined and restored to their original condition after fracturing, whereas others will produce a repulsive force at the fracture site, thereby preventing them from being rejoined?

The Source of the Magnetic Force of Magnets

Before understanding this issue thoroughly, we must first know where the magnetism of a magnet comes from. Artificial magnets don’t possess magnetic force right after being molded. Only after being magnetized can they become real magnets.

Whether a magnet has magnetism depends on the arrangement direction of its internal magnetic domains. Before being magnetized, the magnetic domains of the magnet are arranged in a disorderly fashion. Although each individual magnetic domain area possesses magnetism, the different magnetic field directions result in the cancellation of their magnetic forces among them. From a macroscopic perspective, it is merely an alloy that does not display magnetism.

During the magnetization process of a magnet, a directional strong magnetic field will be applied externally. This external strong magnetic field causes the originally disordered magnetic domains inside the magnet to become uniformly aligned in the same direction, thus transforming it into a magnetic magnet.

Pole Distribution and Fracture Direction

After the magnetization process is completed, the alignment direction of the magnetic domains inside the magnet will be basically consistent with the magnetization direction applied externally. Meanwhile, the overall alignment trend of the magnetic domains also determines the distribution of the magnetic poles of the magnet.

1.The fracture surface is perpendicular to the magnetization direction

Take the bar magnet commonly used in our daily life as an example. If its magnetization direction is along the length direction, then the S pole and the N pole will be formed at its left and right ends respectively.

From the perspective of the basic physical properties of magnetic fields, magnetic fields inherently possess two key characteristics: continuity and closure. The magnetic field lines of a magnetic field have clear and constant trajectories. They start from the N pole of the magnet and then steadily extend and converge towards the S pole. After reaching the S pole, they will return along a predetermined path inside the magnet in the opposite direction back to the N pole, thus constructing a complete closed-loop structure and ensuring the stable and orderly state of the magnetic field.

When a magnet breaks and the fracture surface is perpendicular to its magnetization direction, the magnet will spontaneously reconstruct the magnetic poles at the fracture surface.

This is because the magnetic field needs to maintain its complete closed and continuous state. After the distribution pattern of the magnetic field lines of the original magnetic field is disrupted, new magnetic poles will inevitably be generated at the newly formed fracture surface, so as to ensure that each individual piece of the broken magnet can construct an independent and complete closed magnetic field line loop.

According to the basic principle of magnetism that like poles repel each other and unlike poles attract each other, in this case, the fracture surfaces of the two magnets respectively show the properties of unlike poles, so there will be an attractive force between them. We can use glue to stick the two magnets together again along the fracture surfaces to repair them.

2.The fracture surface is parallel to the magnetization direction

Conversely, if the magnetization direction is along the thickness direction, then the S pole and the N pole will be formed at its upper and lower ends respectively.This kind of magnet has a larger usage area and can adsorb and fix objects very well.

We also break it in the middle, but its fracture surface is parallel to the magnetization direction. In this case, the path of the magnetic lines of force inside the magnet is not blocked, and the magnetic field can still maintain its original continuity and closure. Therefore, neither of the two separated magnets will form new magnetic poles at the fracture surface.

Since the two magnets have the same magnetic poles at the fracture surface, according to the principle that like poles repel each other, these two magnets cannot be put back together as they were originally.

However, you can also flip one of the magnets so that the magnetic poles at the break can attract each other once more.

3.A more complicated situation

Certainly, the fracture surface may also present a completely irregular shape. Part of it is perpendicular to the magnetization direction, while the other part is parallel to the magnetization direction. Moreover, there will be many tiny magnet fragments with independent magnetic fields at the fracture.

This complex magnetic pole distribution will cause the magnetic force interaction at the fracture to become chaotic. When the fracture surfaces of two magnets are close to each other, it is very likely that some areas will attract each other while some areas will repel each other. This makes it very difficult for the two magnets to be simply rejoined as they would be when the fracture surface is perpendicular to the magnetization direction.

Can mutually repulsive magnets be forcibly put back together?

Even if you use some strong adhesives to force the magnets to stick together, doing so only makes them joined together in appearance. In fact, it doesn’t really repair the damaged magnetic field structure inside the magnets. Moreover, it will also weaken the effective magnetic field of the magnets.

The above is the entire content of the article. If you are interested in our magnets or have other questions, please feel free to contact us.🤗

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