Effect of Al and La Doping on the Structure and Magnetostrictive Properties of Fe73Ga27 Alloy

The changes of microstructure, magnetostriction properties and hardness of the Fe73Ga27−xAlx alloy and (Fe73Ga27−xAlx)99.9La0.1 alloy (x = 0, 0.5, 1.5, 2.5, 3.5, 4.5) were studied by doping Al into the Fe73Ga27 and (Fe73Ga27)99.9La0.1 alloy, respectively. The results show that both the Fe73Ga27−xAlx alloy and (Fe73Ga27−xAlx)99.9La0.1 alloy are dominated by the A2 phase, and the alloy grains are obvious columnar crystals with certain orientations along the water-cooled direction. A proportion of Al atoms replaced Ga atoms, which changed the lattice constant of the alloy, caused lattice distortion, and produced vacancy effects which affected the magnetostriction properties. La atoms were difficult to dissolve in the matrix alloy which made the alloy grains smaller and enhanced the orientation along the (100) direction, resulting in greater magneto-crystalline anisotropy and greater tetragonal distortion, which is conducive to improving the magnetostriction properties. Fe73Ga24.5Al2.5 alloy has a saturation magnetostrictive strain of 74 ppm and a hardness value of 268.064 HV, taking into account the advantages of saturated magnetostrictive strain and high hardness. The maximum saturation magnetostrictive strain of the (Fe73Ga24.5Al2.5)99.9La0.1 alloy is 115 ppm and the hardness is 278.096 HV, indicating that trace La doping can improve the magnetostriction properties and deformation resistance of Fe-Ga alloy, which provides a new design idea for the Fe-Ga alloy, broadening their application in the field of practical production.