Enhanced electrical resistivity in SmFe2-xSix alloys with large magnetostriction

The effects of Si substitution for Fe on phase constitution, electrical resistivity, and magnetostrictive properties have been investigated systematically in SmFe2-xSix alloys. It is found that the main phase of Sm(Fe,Si)2 is surrounded by minor Sm-rich phases at grain boundaries in alloys with x ≤ 0.1, while a large quantity of secondary phases uniformly distributes in the main phase for the samples with x = 0.15 and 0.2. The Sm(Fe,Si)2 Laves phase crystallizes in the trigonal R 3¯ m structure for all the samples at room temperature. The electrical resistivity at 300 K monotonously rises from 75 to 305 µΩ·cm with the increase of x to 0.2, mainly resulting from the existence of secondary phases. Linear magnetostriction of −1260 to −2195 ppm at 20 kOe and magnetomechanical coupling coefficient of 0.37 to 0.46 are obtained in these alloys at room temperature. The optimized combination of electrical resistivity and magnetostriction in SmFe2-xSix materials makes them a promising magnetostrictive material for potential applications in a wider frequency range.