Pathways to High Energy Product FeNi-based Alloys Using Multiple Drivers

INV-18006

Alloys comprised of iron and nickel have been essential to human civilization and adopt cubic crystal structures. A lower symmetry tetragonal phase of FeNi, known as tetrataenite, has been identified as a component of many meteorites and features a high magnetization and a room-temperature magnetocrystalline anisotropy energy density in the range 1.0e1.3 MJ/m3.

In support of the global energy challenge, special attention has been devoted to the development of new magnetic materials, such as L1₀-type FeNi, with the potential to supplement and/or replace rare-earth-based permanent magnets for energy transformation and generation. The incorporation of L1₀ FeNi-based magnets in technological applications is challenged by its formidable synthesis requirements: natural formation of tetrataenite in meteorites requires extraordinarily long cooling periods of up to one billion years. Engineering the development of tetragonality and long-range chemical ordering in the chemically disordered face-centered cubic has proven to be very challenging to date.

 

In this invention, a new phase is proposed as a transitional phase linking cubic FeNi with the chemically ordered tetragonal L1₀ FeNi compound, tetrataenite, as a new advanced permanent magnetic material. This new tetragonal phase was created via application of high-strain processing methods followed by an annealing protocol. High-resolution neutron diffraction affirms that all unprocessed samples adopt the A1-type cubic structure (space group Fm3m) while all fully processed samples adopt the chemically disordered A6-type tetragonal structure (space group I4/mmm). 

The results furnish new fundamental information as well as engineering insight for the terrestrial synthesis of tetrataenite on industrial timescales, with high relevance for the creation of next-generation permanent magnets comprised entirely of easily accessible, earth-abundant elements.

 

- Accelerate phase formation using simultaneous drivers

- Apparatus to process alloys using this method has been built, disclosed. However, the guiding principle of using multiple drivers may be realized in a myriad of processing techniques

- Method is specifically for processing of bulk magnetic alloys

 

- Permanent magnets permit interconversion of mechanical and electrical energy to enable critical technologies in alternative energy, medical, communications systems, and military applications

- Motors, generators and other power applications

 

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