Giant Magnetoimpedance in As Cast Fe84Nb3.5Zr3.5B9-xCux Ribbons

In the present work the giant magnetoimpedance of Fe84Nb3.5Zr3.5B9-xCux as cast ribbons was reported. With increasing Cu content. the magnetoimpedance increases at first. experiences a maximum value at about x 3, and then decreases again at high Cu content. The value Of magnetoimpendance Delta Z/Z(0) = (Z(H) - Z(0))/Z(0) for Fe8.4Nb3.5Zr3.5B6CU3 (x = 3) as cast ribbon is -37.5% under H = 7162 A/m at 700 kHz. The large magnetoimpendance for Fe84Nb3.5Zr3.5B6Cu3 is connected with the strong change of transverse permeability. The grain size of alpha-Fe derived from (200) peak based on ScheFrer ' s equation is 19 nm for Fe84Nb3.5Zr3.5B6Cu3 (x = 3), 13 nm for Fe84Nb3.5Zr3.5B5Cu4 (x = 4) and 11 nm for Fe84Nb3.5Zr3.5B4Cu5 (x = 5). respectively. The high Cu addition in Fe-(Nb,Zr)-B-Cu not only enhances the nucleation of alpha-Fe in as cast ribbon, but also reduces its grain size. The present experimental results indicated that Fc-(Nb,Zr)-B-Cu nanocrystalline materials with large magnetoimpedance can be fabricated with nielting-spinning method without annealing.