MAGNETOSTRICTION AND ITS TEMPERATURE-DEPENDENCE IN FECUNBSIB NANOCRYSTALLINE ALLOY

The temperature dependencies of the linear saturation magnetostriction of Fe73.5CuNb3Si15.5B7 nanocrystalline alloy have been measured for t he samples exhibiting a wide range of the crystalline phase volumetric fraction obtained by a proper annealing procedure. It has been proved that the effective magnetostriction of this material can be interpret ed as a volumetrically weighted balance among two contributions, a neg ative one (for the bcc-Fe(Si) nanocrystallites) and a positive one (fo r the residual amorphous matrix). The measured temperature dependencie s of the effective magnetostriction have been analyzed in order to cal culate both contributions to this quantity. This analysis was performe d assuming linear as well as quadratic approximation of the dependence of the effective magnetostriction on the nanocrystalline fraction sho wing that the former reflects better the properties of the material. T he above analysis also showed that, in order to obtain zero-magnetostr ictive material at room temperature, the fraction of nanocrystallites should be relatively large (similar to 70-80%).