Temperature and magnetic field dependencies of the Young's modulus in magnetostrictive Fe-Ga alloys

Abstract

Anomalous temperature dependences of Young's modulus were observed in the as-cast and directionally solidified Fe100-xGax alloys (x = 20, 22, 24, 27). However, the absence of the anomalous temperature dependence of Young's modulus in the DO19 and L12 ordered Fe73Ga27 alloys revealed that the anomalous temperature dependences of Young's modulus of Fe-Ga alloys with different structures were only related with the structure transformation during the heating process. The relationship between the variations of Young's modulus and structural transformation in the Fe78Ga22 alloy indicated that the lattice shrinkage owing to the structural transformations of A2 → DO3 and BCC(A2/DO3) → L12 was offset by the lattice expansion of the A2 phase caused by the thermal effect, which lead to a near constant coefficient of Young's modulus in the temperature range from 500 °C to 560 °C. In addition, the variability of Young's modulus as high as 12.8% was obtained in the as-directional solidified Fe73Ga27 alloy.