THE INFLUENCE OF THE CASTING PARAMETERS AND OF THE SURFACE QUALITY ONMAGNETIC AND MAGNETOELASTIC PROPERTIES OF THE AMORPHOUS CO21FE64B15 ALLOY

The influence of the casting parameters and of the surface quality upo n DC hysteresis loops J(H) and field dependence of the Young's modulus E on the applied field H was studied for 6 mm wide ribbons of the Co2 1Fe64B15 amorphous alloy. Five ribbons were prepared by melt-spinning technique with the different thermal history of the melt. The as-cast ribbons exhibited different levels of quenched-in stresses and differe nt surface topology, as determined by surface profiling and optical mi croscopy. A correlation was found between the thermal history of the m elt and the surface topology of the ribbons. The as-quenched ribbons w ere stress-relieved at 263 degrees C x 2 h in vacuum and after the str ess-relief DC J(H) and E(H) curves were measured. The coercivity and t he magnitude of Delta E-effect increased and the initial susceptibilit y decreased with increasing surface roughness. There was, however, fou nd no correlation between surface roughness and saturation magnetostri ction of the stress-relieved samples. The annealing in transverse magn etic field (265 degrees C x 2 h x 358 kA m(-1) in vacuum) removed almo st all differences between materials, excepting the material with the worst surface quality. (C) 1997 Elsevier Science S.A.