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The high-frequency initial magnetic permeability and its relaxation have been studied in Fe62.5Co6Ni7.5Zr6Cu1Nb2B15 after heat treatment (both in furnace or via DC Joule heating). The magnetic permeability steadily increases in correspondence of both structural relaxation and nanocrystallisation of the alloy. The intensity of the permeability relaxation (measured between fixed times after demagnetisation) is reduced by structural relaxation but exhibits a sharp maximum immediately before the onset of nanocrystallisation. The nanocrystalline alloy is characterised by a nonzero, if reduced, permeability relaxation.

We have produced ribbons of Co1-xPx (x almost-equal-to 0.09) with the coexistence of microcrystalline and amorphous structure. These kind of materials have different magnetic and magnetostrictive behaviour in comparison with that already known of crystalline or amorphous specimens (x almost-equal-to 0.05 and 0.12, respectively). In particular we demonstrate the obtaining of good magnetoelastic response and, at the same time, the results validate the structure sensitivity of resonant magneto-acoustic waves. The complete behaviour of wave amplitude as a function of the applied magnetization field is compared for each sample and explained.

Mossbauer spectra, susceptibility and magnetization measurements were performed on Fe 40 Ni 40 P 14 B 6 amorphous ribbons. The results indicate the existence of correlated ferromagnetic regions of different sizes. With decreasing temperature a collective freezing of the resulting moments occurs with cluster-glass-like characteristics.

The behaviour of low field magnetization versus temperature is strictly dependent on phosphorus atomic fraction in Co 1− x P x alloys, namely on the structure of the material. In particular the presence of a transition to reentrant magnetization at low temperature is validate and its relation with the degree of disorder demonstrated.

Laser annealing of amorphous alloy ribbons was performed by irradiating either their smooth or rough side. Experimental results such as hyperfine field distributions, average orientation of the magnetic moment, X-ray diffractography, initial permeability, magnetic anistropy, and low field magnetization, show the influence of the surface characteristics on the effects induced by the laser treatment. In particular, the effects of an applied tensile stress are compared to eachother and with previously obtained results. Many results are explained by means of the crystallization occurrence (at surface and also bulk) and taking into account its dependence on the irradiated surface properties and interaction time.