Achieve High Efficiency & Low Loss: A Complete Guide To Amorphous & Nanocrystalline Cores

In power electronics, new energy, telecommunications and other fields, magnetic cores serve as key components for energy conversion and signal transmission. Their performance directly determines the efficiency, size and stability of equipment. With core advantages of high efficiency, low loss and high permeability, amorphous and nanocrystalline magnetic cores are gradually replacing traditional silicon steel and ferrite cores, becoming the preferred material for high-end equipment. This article explains amorphous and nanocrystalline cores in four aspects: definition, working principle, performance advantages and selection guidelines.

 

1. What Are Amorphous & Nanocrystalline Cores?

Amorphous and nanocrystalline cores are soft magnetic components made from amorphous alloys and nanocrystalline alloys through forming, annealing and other processes.

• Amorphous alloys are produced using rapid solidification technology, in which molten metal is cooled at an extremely high rate (above 10⁶°C/s) to form an alloy with a disordered, non-crystalline structure.
• Nanocrystalline alloys are developed on the basis of amorphous alloys through subsequent annealing, which precipitates nanoscale crystalline particles ranging from 1 to 100 nm, forming a dual-phase structure of amorphous matrix + nanocrystalline grains.

Compared with traditional silicon steel and ferrite cores, amorphous and nanocrystalline cores feature a more uniform microstructure and smoother magnetic domain switching, resulting in superior soft magnetic properties.

 

2. Core Performance Advantages (vs. Traditional Cores)

The benefits of amorphous and nanocrystalline cores are concentrated in four areas: low loss, high permeability, high saturation magnetic flux density, and wide temperature stability.

• Low Loss: Under high-frequency conditions (1 kHz–1 MHz), core loss is only 1/5 to 1/10 of conventional silicon steel cores and 40% of ferrite cores. This effectively reduces energy consumption, lowers heat generation and extends service life.
• High Permeability: Initial permeability can reach 10⁴–10⁵, much higher than silicon steel (10³ level) and ferrite (10³–10⁴ level). Ideal for weak signal transmission, high-frequency filtering and high-precision signal applications.
• High Saturation Magnetic Flux Density (Bs): Bs reaches 1.2–1.5 T, close to silicon steel and significantly higher than ferrite (0.3–0.5 T). Under the same magnetic field strength, it allows smaller core size and equipment miniaturization.
• Wide Temperature Stability: Operating temperature range of -55°C to 150°C, with stable magnetic performance in high and low temperature environments, suitable for complex working conditions such as new energy vehicles and outdoor power equipment.

 

3. Core Structure & Working Principle

The outstanding performance of amorphous and nanocrystalline cores comes from their unique dual-phase microstructure.

The amorphous matrix provides excellent flexibility and corrosion resistance, while nanocrystalline grains act as magnetic domain centers, accelerating domain rotation and movement to reduce hysteresis and eddy current losses. When an external magnetic field is applied, magnetic domains align along the field direction to achieve energy conversion and transmission. When the field is removed, domains return to a disordered state, completing one energy cycle.

Annealing is critical to optimizing performance: precise control of annealing temperature (400–550°C) and holding time adjusts the size and distribution of nanocrystalline grains, fine-tuning key parameters such as core loss and permeability for different applications.

 

4. Key Selection Criteria

Selection should be based on application scenario, operating frequency, magnetic field strength and other factors, focusing on four points:

• Frequency Matching: For high-frequency applications (e.g., 5G communications, wireless charging above 1 MHz), prioritize nanocrystalline cores. For low-frequency use (e.g., power frequency transformers at 50 Hz–1 kHz), amorphous cores balance loss and cost.
• Loss Requirements: For energy-sensitive equipment (e.g., PV inverters, NEV OBCs), select low-loss grades and focus on high-frequency core loss parameter (Pcv).
• Size Constraints: For miniaturized devices (portable electronics, on-board modules), choose nanocrystalline cores with high Bs and high permeability to reduce dimensions while maintaining performance.
• Environmental Adaptability: For outdoor, high or low temperature environments (industrial control, automotive equipment), select wide-temperature-stable amorphous and nanocrystalline cores to avoid performance degradation due to temperature changes.

 

Summary

With advantages of low loss, high permeability and compact size, amorphous and nanocrystalline cores are widely used in high-end fields including new energy, communications and power electronics. Understanding their structural principles and selection rules helps maximize performance, support equipment upgrading and achieve energy saving and consumption reduction.