Nanocrystalline cores, characterized by high magnetic permeability, high saturation magnetic induction, and excellent temperature stability, have been widely used in power systems, electronics, and electric vehicles industries. They are also a key focus in the research and development of soft magnetic cores.
Meaning of Core
The purpose of a motor core is to provide a stable magnetic path. When current flows through the motor’s coils, the generated magnetic field produces magnetic flux within the core. The design and material selection of the core aim to minimize magnetic flux loss, maximize electromagnetic power conversion, and efficiently convert electrical energy into mechanical energy, thereby improving motor efficiency.
Meaning of Nanocrystalline Materials
Amorphous alloys are metals with disordered atomic arrangements obtained by rapidly cooling molten metal to inhibit crystallization, often referred to as “liquid metal.” Due to their unique structure, amorphous alloys exhibit isotropy, small structural dimensions, and low magnetic anisotropy constants, resulting in low coercivity while maintaining high saturation magnetic induction similar to crystalline materials.
Nanocrystalline alloys are formed by subjecting amorphous materials to special heat treatments to create and grow crystalline nuclei, controlling the grain size to within the nanoscale (less than 100 nanometers) without forming complete crystals. This results in a mixed structure of amorphous and nanocrystalline phases. The most widely used nanocrystalline alloys are iron-based, primarily composed of Fe, Ni, Si, B, and P.
Advantages of Nanocrystalline Cores
Excellent Temperature Stability
Iron-based nanocrystalline alloys have a Curie temperature above 570°C, offering excellent temperature stability with performance changes close to linear. Typically, nanocrystalline alloys operate in a temperature range of -50°C to 130°C, with major magnetic performance changes within 10%. In contrast, ferrites have a Curie temperature below 250°C, with magnetic performance changes sometimes exceeding 100%.
Lower Losses
The low loss characteristics of amorphous alloy materials result in iron core losses much lower than those of traditional silicon steel sheet cores. Nanocrystalline cores have losses in the medium to high-frequency range that are only 1/8 to 1/10 of silicon steel sheet cores, with this low-loss characteristic becoming more pronounced at higher frequencies. Therefore, nanocrystalline cores are more efficient than traditional core materials, making them particularly suitable for medium to high-frequency applications.
High Saturation Magnetic Induction & High Magnetic Permeability
Iron-based nanocrystalline cores have a high saturation magnetic induction (1.2T), more than twice that of traditional core materials. They also exhibit excellent magnetic permeability (>80000), far exceeding traditional core materials like ferrites. 
Equipment Miniaturization
Due to their excellent magnetic properties and low losses, motors using nanocrystalline cores can theoretically achieve an operational efficiency of over 95%, reaching up to 98%. In comparison, traditional silicon steel sheet motors are much less efficient, meaning motors made with new materials can be smaller for the same power output.
Flexible Frequency Characteristics
Through different manufacturing processes and appropriate coil turns, nanocrystalline cores can exhibit excellent magnetic permeability characteristics and low losses across a wide frequency range. For instance, different core materials, sizes, and turns can be selected to meet varying filtering requirements for different frequency bands in filter applications.
| Parameter | Silicon Steel | Iron-based Amorphous | Iron-based Nanocrystalline | Iron Powder | Mn-Zn Ferrite |
| Saturation Magnetic Induction (T) | 2.03 | 1.56 | 1.25 | 1.40 | 0.50 |
| Coercive Force (A/m) | 40 | <4 | <2 | 8 | |
| Initial Magnetic Permeability | 1500 | 5000 | 80000 | 10-75 | 3000 |
| Max. Magnetic Permeability | 2*10^4 | 5*10^4 | 4*10^5 | 6000 | |
| Resistivity (uΩ-cm) | 50 | 130 | 90 | 11 | 80*10^7 |
| Curie Temp. (°C) | 750 | 410 | 410 | 700 | 200 |
Applications of Nanocrystalline Cores
Electric Vehicles
Electric vehicles require a flat structure and a speed range of 2000-6000 rpm motors. High-frequency changes in the motor can cause a significant increase in iron losses, reducing efficiency and posing cooling challenges. Nanocrystalline core motors can greatly reduce high-frequency iron losses, improve efficiency, and address the application challenges of permanent magnet motors in electric vehicles.
Power Systems
In the power electronics field, nanocrystalline cores offer both high saturation magnetic induction and low high-frequency losses with good thermal stability, making them suitable for high-power switching power supplies. Transformers using nanocrystalline cores can achieve power conversion up to 500kW, reducing the volume by more than 50% compared to traditional transformers.
High-Frequency Electronics
Nanocrystalline cores are used in high-frequency electronics mainly as core materials for various electromagnetic interference (EMI) filters. Compared to traditional cores, nanocrystalline cores offer high magnetic induction, low losses, and stable performance.
Nanocrystalline Cores Provider in China
At Tengye, we’re thrilled to be early participants in your new projects. We hope to bring our knowledge and experience to the forefront by actively engaging in your upcoming projects.
Image Source: Intechopen & Web & E-magnetsuk & Nanocrystalline-strip & SpringerLink & gotrend
