Magnetostriction constants for Fe-Al-Si (Sendust) single crystals with DO3ordered structure

The magnetostriction constants, λ100and λ111of 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 λ100is positive at -196°C and the magnitude of λ100is fairly large (1.3&times10^-5). With increasing temperature, the magnitude of λ100becomes gradually smaller and crosses zero at room temperature. With further increasing temperature, λ100again increases (-2×10^-6at 120°C). While in the case of the λ111, no sign change of λ111took place and the magnitude of λ111is 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 λ100becomes zero is strongly temperature dependent. With increasing temperature, the compositional line of λ100=0 moves to the area with rich Fe and less Si concentration in the Fe-Al-Si ternary alloy system. The composition at which λ100=0 and K1=0 are both realized by shifts to lower Si concentration region in Fe-Al-Si ternary alloy system with increasing temperature.