Magnetostriction of polycrystalline strong-textured Fe-17at%Ga laminates

Magnetostrictive bulk Fe-17at%Ga alloy was fabricated by combining laminates of rapid-solidified ribbons (80 μm in thickness) using the spark plasma sintering/joining (SPSJ). The SPSJ is characterized by a short time, low temperature heating and sintering process. The laminated sample made by the SPSJ maintained a unique metallurgical microstructure of polycrystalline texture of columnar grains, as well as the almost non-equilibrium metastable phase with little evidence of the precipitates of the ordered phases as found in the as-spun ribbons. An excellent sintered sample exhibiting large magnetostriction was obtained under a condition of compressive stress of 100MPa at a temperature of 973 K. The magnetostriction depended on compressive pre-stress level for each specimen and reached about 100ppm, which was half the value obtained for the ribbon sample. Furthermore, by subjecting this specimen to a short annealing process, the magnetostriction increased to 170ppm, comparable to the value for the ribbon.