The growth velocity has a significant effect on the preferred orientation of the directionally solidified Fe81Ga19 magnetostrictive alloy. Strong <100> preferred orientation was obtained for a velocity range from 10mm/h to 20mm/h. An excellent magnetostriction λ100 of 294×10-6 was achieved for the <100> oriented crystal at a pre-stress of 74.1MPa. Linear and volume magnetostrictions were investigated in the as-cast Fe81Ga19 alloys with A2 phase by measuring the change in length along the three-dimensional directions of the samples. Due to the contribution of the volume magnetostriction, the longitudinal magnetostriction increased from 27 ppm at 0.3 T to 47 ppm at 2.0 T. The volume magnetostriction can be drastically enhanced by doping Ga in Fe.