Effect of annealing under tensile loading on the structure of nanocrystals in the Finemet alloy

The effect of nanocrystallization annealing under tensile loading on the structure of nanocrystals in the soft magnetic alloy Fe–Si–Nb–B–Cu (Finemet) has been investigated. It has been shown that the body-centered cubic (bcc) lattice of $\alpha$-FeSi nanocrystals is extended along the direction of the application of the load upon annealing and is compressed in the transverse direction. Nanocrystals in the Finemet alloy have a higher degree of anisotropy of mechanical properties as compared to bulk crystals of $\alpha$-FeSi, so that agreement between the measured and calculated values of the elongation is achieved only with a significant increase in the elastic moduli. Substantial changes in mechanical properties of the crystals with a decrease in their size to the nanometer scale are caused by the influence of the rigid amorphous matrix of the Fe(Nb)–B phase surrounding the nanocrystals.