MEASUREMENTS OF THERMAL AND MAGNETOVOLUME CHANGES OF SOFT FERROMAGNETIC RAPIDLY QUENCHED MATERIALS

Gabriel Vlasák – Peter Švec

   Enhanced and outstanding physical properties, especially magnetic properties, are one of the reasons of attractivity of rapidly quenched materials for researchers. In the course of their thermal treatment aimed at optimization of the properties or during their applications, however, reversible as well as irreversible volume or shape changes are observed which take place due to the influence of external thermal and magnetic fields. A special dilatometer has been designed and constructed in order to quantify these changes on samples in form of thin ribbons, including changes due to magnetic processes taking place under and around the Curie temperature; the so-called invar effect, ie spontaneous volume magnetostriction as well as coefficient of thermal dilatation can be determined. The measurements of these effects are illustrated on two sets of samples belonging to the Fe_1-xB_x (x = 14, 16, 17, 20, 23, 25) and (Fe_1-xCo_x)₈₁Nb₇B₁₂ (x = 0, 0.25, 0.33, 0.5) systems.

Keywords: metallic glass, spontaneous volume magnetostriction, coefficient of thermal dilatation, dilatometry

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