The low frequency pulse magnetic field leads the amorphous thin strip Fe78Si9B13 to produce nano crystallization, precipitating α-Fe (Si) nano phase, and then forming α-Fe (Si) nanocrystalline and residual amorphous dual phase nanocrystalline alloy. Mossbauer spectral analysis, with the strength of the pulse magnetic field, crystallization phase volume fraction of dual phrase nano crystalline alloy increases. The magnetostrictive coefficient λcs CS of nano crystalline phase of α-Fe ( Si ) is negative, with range from- 1.287×10-4 to - 1.345×10-4.Controlling crystallization phase volume ratio can minimize the effective magnetostrictive coefficient λes of dual phase nanocrystalline alloy, benefiting the improvement of dual phase nanocrystalline alloy soft magnetic properties.

Low frequency impulse magnetic field process can cause amorpfous alloy ribbons which are made of (Fe _1-xCo _{x }) ₈₆Hf ₇B ₆Cu _1(x=0.4) to crystallize - Fe.    (Fe _1-xCo _x) ₈₆Hf ₇B ₆Cu _1(x=0.4) indicates postive saturated magnetostriction coefficient and -Fe indicates negative saturated magnetostriction coefficien.Promoting the magnetic field intensity and the processing time can adjust the degree of the crystallization, make the ratio between the volume of λSA and the volume of λSB achieve optimization and minimize the saturated magnetostriction coefficient λS of sample.