Magnetic properties and surface roughness of Fe64Co21B15 amorphous ribbons quenched from different melt temperatures

The effect of different melt temperature and of surface roughness on the magnetic properties of the amorphous phase in Fe64Co21B15 alloy prepared by Planar Flow Casting (PFC) has been investigated. The obtained ribbons have been magnetically characterized analyzing hysteresis loops and coercivity in the as-cast condition, after relaxation induced by field-annealing treatment and after thinning by chemical etching. Differential Scanning Calorimeter (DSC) has been used to quantitatively characterize structural relaxation and crystallization of the amorphous phase, Optical and Scanning Electron Microscopy (SEM) have been used to evaluate surface roughness. The average size of the surface grooves on the wheel side was found to increase with melt temperature and thickness. Magnetic properties have been observed to be mainly influenced by the roughness on the wheel side of the ribbons and surface frozen-in stresses are considered to be the main source for the magnetic anisotropy. Crystallization process doesn't vary significantly among the samples, while relaxation heat was found to increase with thickness reduction. Melt temperature was related to previous remarks as controlling viscosity and thus modifying the wetting grade of the melt onto the cooling substrate. (C) 1997 Elsevier Science S.A.