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

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 2022-2023):

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 magnetsM. 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.

Products:

• Powders with total volume of α ″ -Fe16N2 phase about, 87.64% and saturation magnetization, Ms= 238.8 emu / g;

Reports:

2022 Activity Report Summary (in Romanian)
2023 Activity Report Summary (in Romanian)