Magnetostriction constants for Fe-Al-Si (Sendust) single crystals with DO<inf>3</inf>ordered structure

Abstract

The magnetostriction constants, λ 100 and λ 111 of the Sendust alloys (7∼11wt%Si,4∼7wt%Al,bal.Fe) were determined as a function of the tempeature between -196°C and 120°C by means of the strain gauge method. For the central composition of Sendust alloy (9.6wt% Si,5.7wt% Al,bal.Fe), the sign of λ 100 is positive at -196°C and the magnitude of λ 100 is fairly large (1.3&times10-5). With increasing temperature, the magnitude of λ 100 becomes gradually smaller and crosses zero at room temperature. With further increasing temperature, λ 100 again increases (-2×10-6at 120°C). While in the case of the λ 111 , no sign change of λ 111 took place and the magnitude of λ 111 is nearly constant (e.g.-1×10-6for the central composition of Sendust alloy) in this temperature range for most of the alloys examined. The composition at which λ 100 becomes zero is strongly temperature dependent. With increasing temperature, the compositional line of λ 100 =0 moves to the area with rich Fe and less Si concentration in the Fe-Al-Si ternary alloy system. The composition at which λ 100 =0 and K 1 =0 are both realized by shifts to lower Si concentration region in Fe-Al-Si ternary alloy system with increasing temperature.