Effect Of Similar Elements Addition On Glass-forming Ability And Magnetic Properties Of Fe-based Fe-P-C Metallic Glasses

Fe-based bulk metallic glasses(BMGs)not only have high strength,high hardness,and good corrosion resistance,but also show excellent soft magnetic properties such as low coercivity(H_c),low iron loss,and high permeability.Fe-based amorphous ribbons have been used in power electronic equipments and devices such as transformers,mutual inductors and reactors.Fe-based metallic glasses are mainly composed of Fe and metalloid elements.In order to improve the glass-forming ability(GFA),amorphous forming elements such as Al,Ga,Nb,Mo,and Y are usually added to the alloy.However,these elements will reduce the saturation magnetic flux density(B_s).Addition of similar elements can effectively improve the GFA,and the metalloid elements and ferromagnetic elements Co and Ni will not significantly affect the B_s of Fe-based metallic glasses.Therefore,the addition of similar element is an effective way to develop Fe-based BMGs with high GFA and B_s.A Fe₈₀P₁₃C₇ metallic glass has good soft magnetic properties with a B_s as high as 1.56 T and a H_c low to 2.9 A/m;the alloy shows obvious glass transition and has a supercooled liquid region(?T_x),indicating the good GFA.In this paper,in order to develop Fe-based BMGs with high B_s,the composition design and optimization were carried out by adopting the similar elements substitution strategy.The metalloid elements B and Si were used to replace the P and C in the Fe₈₀P₁₃C₇ alloy,respectively,and ferromagnetic elements Co and Ni were used to replace the Fe.The effects of alloying elements on the thermal properties,GFA,and magnetic and mechanical properties were studied,and the correaltion between alloy composition and properties was discussed.The main research results are as follows:1.For Fe₈₀P_13-xB_xC₇(x=0-13)metallic glasses,with the increase of B content,the glass transition temperature(T_g)and onset temperature of crystallization(T_x)gradually increase from663 and 696 K to 727 and 756 K,respectively,the?T_x increases first and then decreases getting the maximum?T_x of 35 K at x=4.The alloy with x=4 also has the maximum reduced glass transition temperature(T_rg)and the?value,and the BMG with a critical diameter(d_c)of 1 mm can be obtained by a copper mold casting method.With increasing the B content,the B_sgradually increases from 1.56 T to 1.72 T,while the H_c first decreases from 2.9 A/m to 0.9 A/m at x=4,and then gradually increases to 1.7 A/m at x=13.A Fe₈₀P₉B₄C₇ metallic glass has good soft magnetic and mechanical properties,the B_s,H_c,compressive yield strength(?_c,y),and plastic strain(?_c,p)are 1.63 T,0.9 A/m,2847 MPa,and 0.3%,respectively.2.For Fe₈₀P₉B₄C_7-xSi_x(x=0-7)metallic glasses,with the increase of Si content,the T_xgradually increases from 722 K to 755 K.The BMG samples can be obtained in the range of x=0-5,and the d_c reaches 1.5 mm at x=2,although the glass transition disappears after adding Si,With enriching of Si element,the B_s keeps in the range of 1.63-1.64 T,while the H_c increases from 0.9 A/m to 4.1 A/m.Fe₈₀P₉B₄C_7-xSi_x(x=0-5)BMGs also show good soft magnetic and mechanical properties,and the B_s,H_c,?_c,y,and?_c,p are 1.63-1.64 T,0.9-4.1 A/m,2847-3064,MPa and 0.3-1.1%,respectively.3.After replacing Fe with Co,the T_g of Fe_80-xCo_xP₉B₄C₇(x=0-10)metallic glasses increases from 687 K to 705 K,and the?T_x decreases from 35 K to 20 K.The addition of Co effectively increases the B_s from 1.63 T to 1.68 T,and the H_c increases from 0.9 A/m to 12.2A/m.The Fe_80-xCo_xP₉B₄C₇ alloys has good GFA and can form BMGs with x=0-10,and the d_creaches 1.5 mm when x=10.The Fe₇₀Co₁₀P₉B₄C₇ BMG possesses the highest B_s among the reported soft magnetic BMGs.4.After replacing Fe with Ni,the T_g and T_x of Fe_80-yNi_yP₉B₄C₇(y=0-10)metallic glasses decrease from 690 K to 681 K and from 725 K to 717 K,respectively,and the?T_x remains at around 34 K.The alloys all can be prepared into BMGs with the d_c of 1 mm.With the increase of Ni content,the B_s decreases from 1.63 T to 1.51 T,and the H_c increases from 0.9 A/m to 3.4A/m.