The brittleness of NdFeB magnets is a topic for discussion in this article. With its superior magnetic properties, the NdFeB magnet is widely used in modern technology and industrial fields. Nowadays, with the expansion of the use of magnets, people put higher requirements on the performance of NdFeB magnets.
For example, some magnets used in high-speed rotary motors will withstand huge centrifugal force (sometimes even 3G ~ 5G acceleration), which requires the magnets not to be too brittle, otherwise, the NdFeB magnets will be easy to break, affecting their practical application.
Why NdFeB Magnets are Brittle
Molecule Structure | The alignment of neodymium, iron, and boron is critical for their magnetic strength, but the bonds between the molecules are fragile to the shear forces.
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Production Process | The production process of NdFeB magnets is a typical powder metallurgy process, so the mechanical properties of magnets are very similar to ceramic materials, which are characterized by being brittle and hard.
Elements | NdFeB magnets contain a large number of metal elements, such as iron. This causes the magnet to react easily with oxygen in the air. This oxidation will further exacerbate the brittleness of NdFeB magnets.
Mechanical Processing | When mechanically cutting and processing, if the grinding wheel does not have good thermal conductivity, it will lead to localized high temperature of NdFeB blankets, resulting in surface oxidation and cracks. The final product is also brittle and easily fractured.
Raw Materials | The raw materials used to produce NdFeB magnets are second-hand recycled materials. Such magnets are more brittle than those made from new materials.
Solutions for the Brittleness of NdFeB Magnets
Design Stage | Optimize Formula Composition
Through experiments, it is found that NdFeB magnets basically break along the crystal interface, so the toughness of NdFeB magnets can be improved by adjusting the composition and optimizing the properties of the grain boundary.
Generally speaking, the lower the total amount of rare earths, the worse the material’s mechanical properties. The higher the Nd content, the higher the bending strength of the material, but this method will also cause a significant increase in cost.
The toughness of magnets can be enhanced by adding low melting point metals such as Cu and Ga in appropriate amounts, and by improving the phase distribution. If the copper content is too high, the magnetic properties of the magnet will be affected.
Adding Nb, Ti, and other high melting point metals, can form a precipitated phase at the grain boundary and inhibit crack extension, which helps to improve the strength and toughness. However, the excessive addition of high melting point metals will cause excessive hardness of the magnetic material, which seriously affects the processing efficiency.
Production Stage | Optimize Production Process
In terms of processing technology, some measures can be taken to reduce the brittleness of NdFeB magnets during processing. For example, in cutting, grinding, and other processes, you can control the processing speed and tool selection to avoid excessive stress concentration and reduce the risk of material rupture. At the same time, in the heat treatment process, reasonable control of temperature and time to avoid excessive hard grain boundaries and interactions can also effectively reduce the brittleness of NdFeB magnets.
Add coatings for NdFeB magnets, the coatings for NdFeB magnets are usually nickel, zinc, epoxy resin, and so on. If the operating environment of NdFeB magnets is harsh, then epoxy resin can be chosen.
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For large-size magnets, add a plastic spacer between magnets during packaging to prevent adsorption and collision between magnets.
Use Stage | Standardize the Use Process
When installing magnet parts, avoid violent collision or twisting of magnets to maintain the integrity of magnets.
During use, be careful to avoid overloading the magnet to avoid excessive stress, thus reducing the risk of magnet breakage.
When storing magnets, avoid placing them in humid or hot environments to avoid damage to their performance. Because NdFeB magnets are more likely to become brittle at high and low temperatures, please avoid prolonged exposure them to extreme temperatures,
To reduce the negative effects of the brittleness of NdFeB magnets, optimizing the material design and production process and other aspects is necessary. This will improve the service life and performance stability of NdFeB magnets, and let them play better roles in various fields.
