Study of magnetostriction and magneto mechanical coupling factors of some magnetostrictive materials

Abstract

The present work describes the experimental investigation of the magnetic properties of Fe100_xA.lx,(where x= 2,3, 10, 12 & 14), Tb.27Dy.73FeZ and also ofNi as a standard materials. Magnetostriction as a function of. the magnetic field' and saturation magnetostriction As for different composition of iron aluminium, iron terbium dysprosium alloy and of nickel as a standard materials are measured. These measurement are confined at room temperature and under at varying field from 0 to 4.5 K Gauss. The saturation field for mag~netostriction in nickel is observed to be 1550 oersted. The . value of magnetic field needed for the saturation magetostriction in Ni determines the operating field for using Nickel as a magnetostrictive transducer. Fe-AI and Tb27DY.73Fez alloys are highly magnetostrictive materials. The magnetotriction value for Fe-Al alloys increases with increasing amount of aluminium and become maximum at 12 atomic percent of Al as due to increased spin-orbit interaction. The decrease of magnetostriction above 12 atomic percent of Al is explained as due to decreasing value of magnetic moment. The field dependance of magnetization for Fe-AI alloys of different composition are measured and the saturation magnetization of alloys decreases with the increasing concentration of Al and the field needed to saturate the magnetization also increases with the increase of Aluminium and the relation is found to be linear. The first anisotropy constant Kl for the iron aluminium alloys system as derived from field versus magnetization curves is similar to the old data derived from magnetization. curves. VI .curves.In general, the addition of aluminium to iron changes the magnetization values. Previous work has shown that up to approximately 20 atomic percent aluminium the . magnetic saturation moment of iron aluminium alloy decreases with. increasing aluminium' content at a rate comparable with what would be expected from simple dilution. Above this concentration the moment falls sharply with increasing aluminium content. The present work is motivated by a ,desire to investigate more fully the effect of order on the saturation magnetization and to fin.d out the magnetization of alloys with aluminium content greater than that reported before who obtained the critical concentration for these specimen by extrapolation