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

Abstract

The magnetostriction constants, λ <inf xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">100</inf> and λ <inf xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">111</inf> 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 <inf xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">100</inf> is positive at -196°C and the magnitude of λ <inf xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">100</inf> is fairly large (1.3&times10 <sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">-5</sup> ). With increasing temperature, the magnitude of λ <inf xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">100</inf> becomes gradually smaller and crosses zero at room temperature. With further increasing temperature, λ <inf xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">100</inf> again increases (-2×10 <sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">-6</sup> at 120°C). While in the case of the λ <inf xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">111</inf> , no sign change of λ <inf xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">111</inf> took place and the magnitude of λ <inf xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">111</inf> is nearly constant (e.g.-1×10 <sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">-6</sup> for the central composition of Sendust alloy) in this temperature range for most of the alloys examined. The composition at which λ <inf xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">100</inf> becomes zero is strongly temperature dependent. With increasing temperature, the compositional line of λ <inf xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">100</inf> =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 <inf xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">100</inf> =0 and K <inf xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">1</inf> =0 are both realized by shifts to lower Si concentration region in Fe-Al-Si ternary alloy system with increasing temperature.