Project summary:

Exchange-spring magnets are comprised of soft and hard magnetic phases dispersed on the nanometric scale and coupled by exchange interactions. The interphase exchange coupling is strongly influenced by the microstructure. Magnetic nanocomposites coupled by exchange interactions will be obtained by different methods: mechanical milling/alloying (powders) and rapid quenching, methods which combined with thermal treatments will optimize the structure and microstructure. The elaboration techniques will lead to the formation of different microstructures. These microstructures will allow the experimental and theoretical study of the correlation between the microstructure and the exchange coupling of the soft and the hard magnetic phases. Aside from the optimal microstructure, the performances of nanocomposite materials coupled by exchange interactions can be influenced by the type of soft and, mainly, hard magnetic phases. Groups of hard/soft magnetic phases, adequate for obtaining a nanocomposite with good coercivity and high remanence will be elaborated and studied. On one hand, we aim to exploit new lean or non-rare-earth hard magnetic phases with high magnetic anisotropy. On the other hand we wish to use soft magnetic phases with magnetization as high as possible (Fe, Fe-Co or other phases based on Fe). We are focusing on a fundamental high-level study on the inter-phase exchange coupling and the proposal of a possible plan for future applications.

Keywords:
 
Hard magnetic materials, spring magnets, magnetization, coercivity, microstructure.