Periodic Reporting for period 1 - REFMAG (Bulk rare earth free permanent magnets)
Période du rapport: 2022-04-01 au 2023-09-30
Permanent magnets are materials that can generate a magnetic field without the need for an external power source. They are widely used in various applications, ranging from electric motors and generators to magnetic sensors and data storage devices. Permanent magnets exhibit several unique features that make them indispensable in many industries. Unlike electromagnets that require a continuous flow of electric current to maintain a magnetic field, permanent magnets retain their magnetic properties even when the power source is removed. This feature makes them suitable for applications where a constant magnetic field is necessary, such as in magnetic storage devices or speakers.
Permanent magnets can possess a high magnetic strength, enabling them to generate strong magnetic fields. Stronger magnets are capable of exerting greater force on magnetic materials, making them ideal for applications where high magnetic forces are required, such as in industrial lifting magnets or magnetic separators. In addition, permanent magnets are known for their stability, meaning their magnetic properties remain consistent over time. They are resistant to demagnetization, meaning they retain their magnetization even in the presence of external magnetic fields. This stability makes permanent magnets reliable for long-term use in various applications.
Permanent magnets come in various shapes and sizes, allowing for versatility in design and application. This flexibility in shape enables their integration into different devices and systems. Permanent magnets exhibit magnetic properties over a broad temperature range, depending on the type of magnet material used. Some magnets, such as neodymium-iron-boron (NdFeB) magnets, cannot maintain their magnetic properties at high temperatures, while others like samarium-cobalt (SmCo) magnets are suitable for use in extreme temperature environments. Due to their ability to generate a magnetic field without the need for an external power supply, permanent magnets contribute to energy-efficient applications. Electric motors and generators that utilize permanent magnets require less energy to operate, leading to improved overall efficiency.
Lastly, permanent magnets can be manufactured in small sizes without sacrificing their magnetic strength. This characteristic is particularly advantageous in the miniaturization of electronic devices, such as smartphones, headphones, or hard disk drives, where space is limited but a magnetic field is still required.
In this project, novel rare-earth free permanent magnets based on α-MnBi were synthesized by severe plastic deformation (SPD) (high-pressure torsion (HPT) processing). The magnetic α-MnBi phase has a high magnetic anisotropy and an increasing coercivity with increasing temperature. Thus, it is also well suited for high temperature applications (i.e. electric motors). If exchange coupled with a soft magnetic phase, the processed permanent magnets could even surpass the magnetic properties of well-established hard magnetic materials. Notwithstanding all described benefits, a commercialization was not realized up to now as synthetization is rather challenging and even more demanding for applications, where bulk materials are inevitable.
Permanent magnets can possess a high magnetic strength, enabling them to generate strong magnetic fields. Stronger magnets are capable of exerting greater force on magnetic materials, making them ideal for applications where high magnetic forces are required, such as in industrial lifting magnets or magnetic separators. In addition, permanent magnets are known for their stability, meaning their magnetic properties remain consistent over time. They are resistant to demagnetization, meaning they retain their magnetization even in the presence of external magnetic fields. This stability makes permanent magnets reliable for long-term use in various applications.
Permanent magnets come in various shapes and sizes, allowing for versatility in design and application. This flexibility in shape enables their integration into different devices and systems. Permanent magnets exhibit magnetic properties over a broad temperature range, depending on the type of magnet material used. Some magnets, such as neodymium-iron-boron (NdFeB) magnets, cannot maintain their magnetic properties at high temperatures, while others like samarium-cobalt (SmCo) magnets are suitable for use in extreme temperature environments. Due to their ability to generate a magnetic field without the need for an external power supply, permanent magnets contribute to energy-efficient applications. Electric motors and generators that utilize permanent magnets require less energy to operate, leading to improved overall efficiency.
Lastly, permanent magnets can be manufactured in small sizes without sacrificing their magnetic strength. This characteristic is particularly advantageous in the miniaturization of electronic devices, such as smartphones, headphones, or hard disk drives, where space is limited but a magnetic field is still required.
In this project, novel rare-earth free permanent magnets based on α-MnBi were synthesized by severe plastic deformation (SPD) (high-pressure torsion (HPT) processing). The magnetic α-MnBi phase has a high magnetic anisotropy and an increasing coercivity with increasing temperature. Thus, it is also well suited for high temperature applications (i.e. electric motors). If exchange coupled with a soft magnetic phase, the processed permanent magnets could even surpass the magnetic properties of well-established hard magnetic materials. Notwithstanding all described benefits, a commercialization was not realized up to now as synthetization is rather challenging and even more demanding for applications, where bulk materials are inevitable.
In REFMAG, rare-earth free permanent magnets based on α-MnBi were synthesized by SPD. Additionally, we set out to demonstrate that the concept of exchange spring magnets is scalable to bulk dimensions and massive high-performance exchange spring permanent magnets can be obtained. As a novel processing route HPT is chosen. With respect to the resource limitation of rare-earth elements, the idea was to use the non-rare earth α-MnBi phase as a hard magnetic phase. Besides its financial affordability, this phase is one of only two known hard magnetic materials, whose intrinsic coercivity increases with rising temperatures. This unique behaviour can be related to its temperature dependent and large magnetocrystalline anisotropy, which definitely renders this phase suitable for high-temperature applications. As soft magnetic phase Fe, but also Ni or alloys, such as FeCo, was used for exchange coupling.
Because of the high applied shear deformation during HPT, a crystallographic preferred direction (texture) developed, forming an anisotropic bulk magnet. Anisotropy is desired as it allows material fabrication with a certain polarity, reducing the amount of material (saving costs and weight) while the magnetic field strength remains constant. In industrial processing, such behaviour is usually induced by a sintering step of a green powder compact. Considering the α-MnBi phase, this process would be limited by an upper temperature of about 250°C due to eutectic decomposition. This additional processing step is redundant for high-pressure torsion processing, as texturing and compaction happened simultaneously. Furthermore, HPT processing decreased grain sizes, which gave an additional increase in coercivity.
With this process, samples up to a diameter of 60 mm and a height of 10 mm can be manufactured. Highlighting HPT processing even more - to our knowledge, there is no other processing route to directly form a bulk α-MnBi material.
Because of the high applied shear deformation during HPT, a crystallographic preferred direction (texture) developed, forming an anisotropic bulk magnet. Anisotropy is desired as it allows material fabrication with a certain polarity, reducing the amount of material (saving costs and weight) while the magnetic field strength remains constant. In industrial processing, such behaviour is usually induced by a sintering step of a green powder compact. Considering the α-MnBi phase, this process would be limited by an upper temperature of about 250°C due to eutectic decomposition. This additional processing step is redundant for high-pressure torsion processing, as texturing and compaction happened simultaneously. Furthermore, HPT processing decreased grain sizes, which gave an additional increase in coercivity.
With this process, samples up to a diameter of 60 mm and a height of 10 mm can be manufactured. Highlighting HPT processing even more - to our knowledge, there is no other processing route to directly form a bulk α-MnBi material.
One of the significant challenges for a new MnBi-based non-rare earth permanent magnet commercialisation in Europe is the development of the supply chain. This includes ensuring access to raw materials, developing efficient extraction and processing methods, and securing long-term supply agreements to meet market demand.
Linked to this, ensuring consistent and scalable manufacturing processes is crucial for commercialization. MnBi-based magnet manufacturing should be capable of producing magnets in large quantities with consistent quality. Efforts to optimize and scale up the manufacturing process, while maintaining tight control over material properties, geometry, and performance, are needed to meet the demands of potential customers.
Achieving cost competitiveness compared to traditional rare earth-based magnets is another critical factor for commercial success. The manufacturing process of MnBi-based magnets may currently be more expensive or less optimized.
In addition, MnBi-based magnets need to demonstrate competitive performance characteristics compared to existing magnet technologies. Improving magnetic strength, temperature stability, coercivity, and other critical properties is essential to meet or exceed the requirements of target applications. Further research and development efforts are needed to optimize the performance of MnBi-based magnets and close the performance gap with established magnet materials.
Demonstrating the viability and superiority of MnBi-based magnets in specific applications is crucial for market adoption. Collaborating with potential end-users, system integrators, and industry partners to validate the technology in real-world applications is important to showcase its value proposition.
Additionally, partnerships can help streamline the manufacturing processes, reduce costs, and scale up production to meet the growing demand for permanent magnets. Furthermore, collaborations (e.g. through subsidies such as EIC Pathfinder/Transition, Eurostars or Horizon Europe calls) can foster research and development initiatives, enabling the exchange of knowledge, expertise, and resources to overcome technical barriers and enhance the overall performance and technical reliability.
Linked to this, ensuring consistent and scalable manufacturing processes is crucial for commercialization. MnBi-based magnet manufacturing should be capable of producing magnets in large quantities with consistent quality. Efforts to optimize and scale up the manufacturing process, while maintaining tight control over material properties, geometry, and performance, are needed to meet the demands of potential customers.
Achieving cost competitiveness compared to traditional rare earth-based magnets is another critical factor for commercial success. The manufacturing process of MnBi-based magnets may currently be more expensive or less optimized.
In addition, MnBi-based magnets need to demonstrate competitive performance characteristics compared to existing magnet technologies. Improving magnetic strength, temperature stability, coercivity, and other critical properties is essential to meet or exceed the requirements of target applications. Further research and development efforts are needed to optimize the performance of MnBi-based magnets and close the performance gap with established magnet materials.
Demonstrating the viability and superiority of MnBi-based magnets in specific applications is crucial for market adoption. Collaborating with potential end-users, system integrators, and industry partners to validate the technology in real-world applications is important to showcase its value proposition.
Additionally, partnerships can help streamline the manufacturing processes, reduce costs, and scale up production to meet the growing demand for permanent magnets. Furthermore, collaborations (e.g. through subsidies such as EIC Pathfinder/Transition, Eurostars or Horizon Europe calls) can foster research and development initiatives, enabling the exchange of knowledge, expertise, and resources to overcome technical barriers and enhance the overall performance and technical reliability.