Project title: Interstitial intermetallic materials of type α″-Fe₁₆N₂ for the new generation of rare-earth-free permanent magnets

Project Acronym: α - FENMAG

Project code:  PN-III-P4-PCE-2021-0298

Contract No.: PCE 2 / 2022

Project Director:  Dr. Marian Grigoras

E-mail: mgrigoras@phys-iasi.ro
Tel: +40 232 430680

Fax: +40 232 231132

Project Funding: 1.000.000,00 RON

Funding Agency: Executive Agency for Higher Education, Research, Development and Innovation Funding (UEFISCDI)

Project Duration: 01/06/2022-30/11/2024 (30 months)

Project Summary:

Permanent magnets (PMs) are critical components used in commercial and military applications. The most used PMs available today are based on Nd-Fe-B with additions of heavy rare earth Dy, Pr, Tb etc. Due to: (i) exponential increase in the request for PMs; (ii) the overall resource limitations, (iii) export restrictions imposed by China (the main supplier) on RE, and (iv) pollution resulting from the extraction and separation of RE, it is imperative necessary development of new RE-free magnetic materials. Consequently, in recent years several new candidate materials systems were investigated, and some have shown realistic potential for replacing RE PMs for some applications.
Our project aims to develop a type of PMs based on α″-Fe₁₆N₂ phase, able to fill in the gap between the most cost-effective but low performing hard ferrite magnet and the most expensive but high performing RE PMs.

The motivation of this choice start, from: (i) the fact that the component materials  of the new magnet, iron and nitrogen are totally non-polluting, and (ii) α″-Fe₁₆N₂ phase promises theoretical a giant saturation magnetization.

The idea is to prepare iron nitride powder by high-pressure gas atomization with high volume ratio of α″-Fe₁₆N₂ phase and compaction of powders by spark plasma sintering technique.

Main Objective of the Project

The main objective of the project is to develop a new generation of permanent magnets without rare earths.

Specific Objectives of the Project

Preparation of iron nitride powders by high-pressure gas atomization technique; study of the influence of parameters involved in process with direct effect on the magnetic properties of the powders;

Nitridation of iron nitride powders in furnace, in order to penetrate the interstitial nitrogen in the structure of iron nitride; evaluation of the α″-Fe₁₆N₂ phase volume ratio;

Development of α″-Fe₁₆N₂ permanent magnets by SPS technique; investigation-optimization of compaction factors / alignment (time, pressure, temperature, magnetic field);

Testing of α″-Fe₁₆N₂ permanent magnets in view of practical applications - “proof-of-concept”.

Expected results:

• Powders with total volume of α ″ -Fe₁₆N₂ phase over 85% and saturation magnetization over 230 emu/g;
• Permanent magnets based on α ″ -Fe₁₆N₂ powders, with an Ms value greater than 230 emu/g;
• 3 papers presented at international conference;
• 1 patent application;
• 4 articles submitted for publication in ISI-rated journals of category Q1 or Q2.

Achieved results (corresponding to the stages completed in the period 2022-2024):

Publications:

1. M. Grigoras, M. Lostun, G. Stoian, G. Ababei, M. Porcescu, and N. Lupu “The Influence of Preparation Parameters on the Morphology and Magnetic Properties of Fe-N Powders Obtained by the Gas Atomization Method” Applied Sciences, 2023, 13, 11529 https://doi.org/10.3390/app132011529
2. M. Grigoras, M. Lostun, M. Porcescu, G. Stoian, G. Ababei, and N. Lupu “ “Innovative method for the mass preparation of α″-Fe₁₆N₂ powders by gas atomization” Crystals, 2023, 13, 1578. https://doi.org/10.3390/cryst13111578

Conference presentations:

1. “Synthesis of α"-Fe₁₆N₂ powders with elongated particles prepared by high-pressure gas atomization technique” M. Grigoras, M. Lostun, M. Porcescu, G. Ababei, G. Stoian, and N. Lupu.
   14th International Conference on Physics of Advanced Materials (ICPAM-14), September 8-15, 2022, Dubrovnik, Croatia.
2. “Preparation by gas atomization of elongated powders α″-Fe₁₆N₂ for anisotropic magnets” M. Grigoras, M. Lostun, G. Ababei, G. Stoian, and N. Lupu
   27th International Workshop On Rare Earth And Future Permanent Magnets And Their Applications-REPM-2023, 3rd-7th September, 2023, Birmingham, UK.
3. “Development of bonded α"-Fe₁₆N₂ permanent magnet” M. Grigoras, M. Lostun, G. Ababei, G. Stoian, and N. Lupu
   IEEE International Magnetics Conference, INTERMAG 2024, 5-10 May 2024, Rio de Janeiro, Brazil.

Products:

• Powders with total volume of α ″ -Fe₁₆N₂ phase about, 87.64% and saturation magnetization, Ms= 230.8 emu/g,
• Permanent magnets based on α″-Fe₁₆N₂ powders, with an Ms=231.2 emu/g.

Reports:

2022 Activity Report Summary (in Romanian)
2023 Activity Report Summary (in Romanian)
2024 Presentation of the project for promotional materials (in Romanian)