Microstructural and magnetic characterization of Nd2Fe17 ball milled alloys

Microstructural and magnetic changes induced by ball milling in Nd₂Fe₁₇ alloy have been investigated. X-ray and neutron powder diffraction studies have shown that the main crystalline phase present in the as-cast Nd₂Fe₁₇ compound is the rhombohedral Th₂Zn₁₇-type crystal structure. Contrary to other materials, the crystal structure does not change after milling, and the crystal lattice parameters slightly increases while the induced strain is less than 0.1%. It has been observed from SEM and TEM images that the microstructure consists of agglomerates of nanoparticles with a mean size around 20 nm, and from magnetic measurements a broadening of the temperature range in which ferromagnetic to paramagnetic transition takes place.