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M: Metallphysik

M 36: Nanoskalige Materialien IV

M 36.3: Fachvortrag

Friday, March 30, 2001, 11:30–11:45, S5.3

Correlation between the structural, magnetic and mechanical properties during the disordering and reordering of ball milled and annealed FeAl — •M.D. Baró — Departament de Física, Universitat Autònoma de Barcelona, 08193 Bellaterra, Spain

It is well known that ball milling can induce different nanocrystalline microstructures in intermetallic powders. In particular, ball-milling FeAl creates a reduction of the crystallite size into the nanometer range, reduces the long-range order and produces an expansion of the lattice and the increase of the microstrains. These effects have been found to induce an important hardening of the alloy and a transition from a paramagnetic state into a ferromagnetic one after ball milling. The structural, magnetic and mechanical properties of the milled materials can be recovered to the original as-obtained values after the appropriate annealings. We will correlate the magnetic and mechanical properties with the different structural processes occurring during milling and the subsequent annealings. Of especial interest is the correlation of the increase in saturation magnetization with the lattice expansion, the strong effect of the magnetic field in the magnetic reordering temperature, the important contribution of the grain boundaries to the magnetization or the importance of the domain/particle size and vacancy hardening.

This work was carried out in collaboration with X. Amils, S. Gialanella, A. Hernando, G. Le Caër, L. Lutterotti, D. Morris, M.A. Morris-Muñoz, J.S. Muñoz, J. Nogués and S. Suriñach. It was supported by INTAS99-1216