Ⅰ. Chemical composition

1. Magnetic element content:

The content of ferromagnetic elements such as iron, cobalt, nickel or combinations thereof plays a key role in magnetism. For example, in iron-based amorphous nanocrystalline materials, increasing iron content usually increases the saturation magnetization.

2. The role of metalloid elements:

Metalloid elements such as silicon, boron, and carbon are also called vitrified elements. Their presence can not only lower the melting point of the alloy and make it easier to form an amorphous state, but also affect the magnetism of the material. For example, an appropriate amount of boron can improve the soft magnetic properties of amorphous nanocrystalline materials.

3. Addition of trace elements:

Adding small amounts of other trace elements (such as niobium, molybdenum, etc.) may have a significant impact on the magnetism by changing the crystal structure, defect state or electronic structure of the material. For example, the addition of niobium can improve the thermal stability of the amorphous phase, refine the grain size of the alloy after heat treatment, and thereby improve the soft magnetism and annealing brittleness.

Ⅱ. Microstructure

1. The ratio of amorphous to nanocrystalline:

The relative amounts of amorphous and nanocrystalline phases affect the overall magnetic properties of the material. Generally speaking, the presence of nanocrystalline phase can increase the saturation magnetization of the material, while the amorphous phase can help reduce hysteresis loss. Optimizing the ratio of the two is the key to obtaining good magnetic properties.

2. Grain size and distribution:

The grain size and distribution of nanocrystals have an important impact on magnetic properties. Smaller and evenly distributed grain sizes are generally beneficial to increasing the material's magnetic permeability and reducing coercive force. If the grain size is too large or the distribution is uneven, the magnetic domain structure inside the material may be uneven, thus affecting the magnetism.

3. Defects and interface:

Defects (such as vacancies, dislocations, etc.) and interfaces (such as the interface between the amorphous phase and the nanocrystalline phase) in the material will affect the arrangement and movement of the magnetic moments, thereby affecting the magnetism. For example, defects may hinder the movement of magnetic domain walls, leading to increased coercive force; while good interface structure can help improve the material's magnetic properties.

Ⅲ. Preparation process

1. Cooling speed:

In the material preparation process, rapid solidification is the key to forming an amorphous state. Extremely high cooling rates (such as more than one million degrees per second) can prevent atoms from being arranged neatly and are "frozen" into an amorphous state. The faster the cooling rate, the easier it is to form an amorphous state, and the more stable the structure of the amorphous state, the greater the impact on magnetism. For example, for iron-based amorphous alloys, when the cooling rate is insufficient, partial crystallization may occur, making the material less magnetic.

2. Annealing treatment:

Annealing process parameters such as annealing temperature, time and atmosphere have an important impact on the magnetic properties of amorphous nanocrystalline materials. Appropriate annealing treatment can promote the formation and growth of nanocrystals in the amorphous matrix, optimize the microstructure of the material, and thereby improve the magnetic properties; however, if the annealing temperature is too high or the time is too long, it may lead to excessive crystallization and deteriorate the magnetism.

3. Molding pressure:

When using methods such as powder metallurgy to prepare amorphous nanocrystalline materials, the molding pressure will affect the density and microstructure of the material. Appropriate molding pressure can make the material denser, reduce pores and defects, and help improve the magnetism; however, excessive molding pressure may cause stress inside the material, which will adversely affect the magnetism.

Ⅳ. External conditions

1. Temperature:

Temperature changes can affect the magnetic properties of amorphous nanocrystalline materials. Generally speaking, as the temperature increases, the saturation magnetization of the material will decrease, the coercive force may first decrease and then increase, and the magnetism will change significantly near the Curie temperature. For example, below the Curie temperature, the material is ferromagnetic; above the Curie temperature, the ferromagnetism disappears and becomes paramagnetic.

2. Magnetic field strength:

The magnitude and direction of the external magnetic field strength will also affect the magnetic properties of the material. Within a certain range, increasing the magnetic field intensity can increase the magnetization degree of the material and increase the saturation magnetization intensity; while a strong magnetic field may cause changes in the magnetic structure of the material and affect its magnetic stability.

3. Stress:

The stress state of a material will change its magnetic domain structure and the arrangement of magnetic moments, thereby affecting its magnetism. For example, tensile stress may reduce the material's magnetic permeability and increase its coercive force; compressive stress may have the opposite effect.