Fracture Toughness, Impact Strength & Flexural Strength: Mechanical Performance of Sintered NdFeB Magnets

Sintered neodymium iron boron (NdFeB) magnets are renowned for their exceptional magnetic properties, but their mechanical performance—particularly fracture toughness, impact strength, and flexural strength—is equally critical for demanding industrial applications. As a leading sintered NdFeB magnet manufacturer, we engineer materials that balance magnetic power with structural reliability. This blog dives into the mechanical metrics defining NdFeB durability and how they impact real-world performance.

• Fracture toughness usually reflects the strength of a material when cracks expand, and its unit is MPa·m1/2. The fracture toughness test of a material requires the use of a tensile testing machine, stress sensor, extensometer, signal amplification dynamic strain gauge, etc. In addition, the sample must be made into a thin sheet.

• Impact strength (impact fracture toughness) reflects the energy absorbed by the material during the fracture process under the impact stress, and the unit is J/m2. The measured value of impact strength is too sensitive to the size, shape, processing accuracy and test environment of the sample, and the measured value dispersion will be relatively large.

• Bending strength is the bending fracture strength of materials measured by the three-point bending method. It is most commonly used to describe the mechanical properties of sintered NdFeB magnets because of the ease of sample processing and simple measurement.

The high strength and low toughness of sintered NdFeB permanent magnet materials are determined by their own crystal structure. In addition, the following two factors will affect the bending strength of sintered NdFeB and are also ways to improve its strength.

• The Nd content has a certain influence on the strength of sintered NdFeB. The experimental results show that under certain conditions, the higher the Nd content, the higher the material strength.

• Adding other metal elements has a certain influence on the strength of sintered NdFeB. When a certain amount of Ti, Nb or Cu is added, the impact fracture toughness of the permanent magnet is improved; when a small amount of Co is added, the bending strength of the permanent magnet is improved.

The low comprehensive mechanical properties of sintered NdFeB is one of the important reasons that limit its application in a wider range of fields. If the toughness of the product can be improved while ensuring that the magnetic properties are improved or unchanged, sintered NdFeB will play a greater role in the military, aerospace and other fields and enter a new period of development.