HREE-free Magnets

HREE-free magnets have become a recent topic of discussion following China’s export controls on heavy rare earth magnets, which is also the subject of this article.

Definition of HREE-free Magnets

HREE-free magnets refer to magnets that do not contain heavy rare earth elements in their composition. Heavy rare earth elements include terbium, dysprosium, holmium, erbium, thulium, ytterbium, lutetium, scandium, yttrium, and others.

Types of HREE-free Magnets

Neodymium Magnets

Tengye has a large inventory of neodymium magnets that can be checked according to your needs, making it convenient for customers to access magnets promptly.

If your demand is small, you can also inform us of your requirements, as some customers are producing large quantities, and small batch materials can be produced together with the materials of large customers.

If the neodymium iron boron magnets you require contain heavy rare earth elements, you can also let us know. With our professional knowledge, we can provide new solutions that may include magnets without heavy rare earths that can meet your usage requirements.

Ferrite Magnets

Composition and characteristics of ferrite magnets: Primarily composed of iron oxides, such as barium ferrite (BaFe12O19) and strontium ferrite (SrFe12O19). Abundant raw materials, low cost, simple production processes, excellent oxidation resistance, and high residual magnetic flux density characterize them. However, their magnetic performance is relatively weak, with a magnetic energy product far lower than rare-earth permanent materials.

Application Fields: Widely used in automotive, home appliances, toys, audio equipment, micro special motors, etc., such as electric windows and mirrors in cars, and motors and speakers in home appliances.

Alnico Magnet

Composition and Characteristics: Mainly composed of aluminum (Al), nickel (Ni), cobalt (Co), and iron (Fe). They have high residual magnetization, high Curie temperature, and small temperature coefficients of residual magnetization, enabling use even in working environments with temperatures up to 500°C. They exhibit minimal degradation of permanent magnetic properties due to temperature changes, but have low coercivity and are difficult to process due to their hardness and brittleness.

Application Fields: Commonly used in fields requiring high reliability, such as electrical instruments and communication devices, and are frequently used in military products, including aerospace, navigation instruments, measuring instruments, electronic clocks, and magnetrons.

Platinum-Cobalt Alloy Permanent Magnets

Composition and Characteristics: A binary alloy with platinum (Pt) as the base, containing cobalt (Co). They exhibit the highest coercivity and relatively high magnetic energy product, possessing strong magnetism and high magnetic stability with excellent resistance to chemical corrosion; neither potassium hydroxide nor concentrated sulfuric acid can corrode them. They can operate in acidic, alkaline, and saline environments, but are expensive.

Application Fields: Mainly used in harsh and specialized environments where other permanent magnetic materials cannot function, such as in aerospace, marine, aviation instrumentation, measuring instruments, electronic clocks, and magnetrons.

Manganese-based Hard Magnetic Materials

Manganese-Aluminum (MnAl) Permanent Magnet Alloys: Feature high magnetic crystalline anisotropy, high coercivity, low density, low cost, excellent corrosion resistance, and good machinability without complex magnetic field treatments, although they present issues with magnetic phase instability and low saturation magnetization.

Manganese-Bismuth (MnBi) Permanent Magnet Alloys: Show high magnetic crystalline anisotropy, moderate saturation magnetization, and positive coercivity temperature coefficients, holding significant potential for applications in mid-to-high temperature ranges. They can be used with neodymium-iron-boron to improve overall magnetic performance.

Manganese-Gallium (MnGa) Permanent Magnet Alloys: Characterized by the absence of rare earth elements, high magnetic crystalline anisotropy, high spin polarization rate, and high Curie temperature, they hold certain potential application value in permanent magnets.

Characteristics of HREE-free Magnets

| Performance: Relatively Low Magnetic Performance: Compared to rare earth-containing magnets, HREE-free magnets generally exhibit lower magnetic energy product. For instance, the magnetic energy product of ferrite magnets is only about one-fifth that of neodymium magnets.

| Coercivity: Some HREE-free magnets have insufficient coercivity, making it challenging to meet the demands of harsh environments such as high temperatures and strong magnetic fields. However, certain HREE-free magnets have been improved in coercivity through special processing or component adjustments.

| Cost: Since they do not rely on scarce and expensive heavy rare earth resources, the raw material costs of HREE-free magnets are relatively low. For example, magnets based on iron oxide have notable cost advantages.

| Environmentally Friendly: The production processes for HREE-free magnets are relatively simple, resulting in less environmental pollution. For instance, the production process for ferrite magnets is mature and has a comparatively small environmental impact.

| Potential for Recycling: After being decommissioned, HREE-free magnets yield metals like iron, aluminum, and manganese, which have high recycling values, and their recycling process is relatively straightforward, aiding resource recycling.

Application Limitations of HREE-free Magnets

Due to performance deficiencies, HREE-free magnets currently struggle to completely replace rare-earth magnets in high-end applications that demand exceptional magnetic performance, such as advanced electric vehicle motors and the aerospace sector. However, they hold broad application prospects in fields with relatively low magnetic performance requirements, such as standard motors and household appliances.