Bulk nanocrystalline hard magnetic Nd-Fe-Al alloys

aim of project
The basic scientific problem is to determine the factors connected with microstructure that decide about Nd-Fe- Al materials acquiring hard magnetic properties. This is a crucial problem when we wish to improve the magnetic properties of these alloys at room temperature. This knowledge is also very interesting from the cognitive point of view, since it is not possible to draw a simple analogy between the microstructure of these materials and that of the materials known so far — this is due to the fact that the basic components of the phase structure of Nd- Fe-Al materials are smaller by an order of magnitude (1–3 nm) than those occurring in other magnetically hard nanocrystalline materials (10–30 nm).

The scientific goal of the project is to fi nd the relationships between the magnetic properties of a solid Nd-Fe-Al material (also when its composition is modifi ed with additional elements) and its microstructure formed of components of nanometric size. The nature of these relationships lies in the interactions between the phases with diff ering magnetic properties.

The applicative goal of the project is to examine whether the magnetic properties that solid Nd-Fe-Al materials have at room temperature can be improved to a level necessary for their wider use in technical applications, and whether it is possible to produce nanocrystalline Nd-Fe-Al alloys in the form of small tubes.

Expected results
The present research mainly has the character of fundamental studies, since these materials have not been used in technical applications yet. The expected results should indicate how to improve the magnetic properties of Nd-Fe-Al alloys so that they are able to compete with other magnetically hard materials. The authors believe that the improved Nd-Fe-Al alloys will be suitable for producing miniature magnets (about 0.2 mm thick) intended for micro-motors. If the present results appear to be positive, they will form the basis for optimization of technology of Nd-Fe-Al magnets.

The present experiments, realized within the project, will include the examinations how the chemical composition of Nd-Fe-Al alloys aff ects their microstructure and properties (in addition to the basic elements, a large group of other alloying elements will be tested), how the method of material casting (cooling rate) affects the properties of the magnets, and whether the properties of the material can be improved by heat treatments. Based on the results obtained, it will be possible to describe the mechanisms of coercivity and the structural factors that enhance them.