Effect Of Element Control On Soft Magnetic Properties Of Fe Based Amorphous Alloys

Fe based amorphous alloys have attracted great attention in power electronics due to their good soft magnetic properties,such as high saturation magnetization(M_s)and low coercivity(H_c).Meanwhile,compared with the silicon steel transformers,the Fe based amorphous alloy transformers can reduce the power consumption by about 70%?80%.However,although Fe based amorphous ribbons with high Fe content(Fe?83 at.%)have good soft magnetic properties,such as saturation magnetic induction of about 1.8 T(Bs?2.0 T),they can not be fully used in high-power products;At the same time,due to the high content of Fe in Fe based amorphous alloy,the content of other trace elements is low,which leads to the weakening of degree of amorphization,the thin strip is very thin and narrow,and the strip is easy to brittle fracture,which limits the application of the alloys.Thus,in this paper,the composition of Fe based amorphous ribbons was optimized on the basis of Fe-Si-B-P-Cu alloy system while the Fe content was higher(?80 at.%),and the effects of different elements on its crystallization mechanism,GFA and soft magnetic properties before and after annealing are studied,so as to obtain amorphous ribbons with good amorphous forming ability and soft magnetic properties.The main research contents and results are as follows:(1)The effects of Nb addition on the amorphization,crystallization mechanism,thermal stability and soft magnetic properties of Fe₈₀Si₄B_11.5-xP₄Cu_0.5Nb_x(x=0,0.5,1,1.5,2 at.%)ribbons were investigated.The experiments show that the addition of Nb can enlarge the GFA.With the addition of Nb,the difference between the two initial crystallization temperatures is effectively enlarged.At the same time,the Fe₈₀Si₄B₁₀P₄Cu_0.5Nb_1.5amorphous alloy ribbons annealed at 520?for 13 min have the best soft magnetic properties,the minimum coercivity H_cis about 0.58 G and the high saturation magnetization M_sis about 178 emu/g.(2)The influences of Cu addition on the glass forming ability(GFA),crystal structure and soft magnetic characteristic of Fe_80.5(Si_0.22B_0.62P_0.16)_18.5-xCu_x(x=0,0.25,0.5,0.75,1 at.%)amorphous ribbons were investigated.The researchs show that when the Cu content is 0.25at.%,the Fe_80.5(Si_0.22B_0.62P_0.16)_18.25Cu_0.25alloy ribbon can form a complete amorphous structure.The addition of minor Cu can enlarge the annealing temperature range(?T_x),while the value of T_x2gradually decreases from 567?to 551?with the addition of Cu,which promotes the precipitation of secondary phase.Fe_80.5(Si_0.22B_0.62P_0.16)_18.25Cu_0.25alloy annealed at 500?can obtain lower coercivity(2.7 G)and higher saturation magnetization(176 emu/g).(3)The effects of pre transition metal elements instead of Fe elements on the degree of amorphization and thermal stability of Fe_80.5(Si_0.22B_0.62P_0.16)_18.5-xCu_x(x=0,0.25,0.5,0.75,1 at.%)amorphous ribbons were investigated.The researchs show that when M=Zr,the precipitation of?-Fe phase can be effectively inhibited and the glass forming ability can be improved.The addition of Nb,Hf and Zr is advantageous to the stability of the amorphous matrix,make the values of T_x1and T_x2move to high temperature.Meanwhile,?T_xis expanded compared with that of Fe,and the maximum expansion of?T_xis 124?when M=Zr.When M=Fe,the M_sof the alloy reaches 167 emu/g.When M=Hf,the M_svalue reaches the minimum of 141 emu/g.