Preparation And Properties Of Transition Metal-Based High Entropy Bulk Amorphous Alloys

High-entropy bulk metallic glasses?HE-BMGs?,as a new type alloy material,combine the advantages of high-entropy alloys and amorphous alloys,and have been attracting the attention of researchers.The work of this thesis focuses on the preparation and properties study of transition metal-based HE-BMGs.The main work includes the following two parts:In the first work,new ferromagnetic(Fe_1/3Co_1/3Ni_1/3)₈₀(P_1/2B_1/2)₂₀0 HE-BMG with the maximum diameter of 2 mm has been prepared by combining fluxing treatment and J-quenching technique.The present HE-BMG exhibits excellent soft magnetic properties with a saturation magnetization of 0.90 T,low coercivity of 1.5 A/m,high permeability of 10172@1KHz and low hysteresis loss of 21KJ/mol@50Hz?for the annealed glassy ribbon?,and mechanical properties with a compressive yield strength of 3000 MPa and large plastic strain of 4%.The combination of superior glass-forming ability,excellent magnetic and mechanical properties makes the present HE-BMG a future promising application as advanced structural and functional materials.In the second work,we study the effect of substituting Cr and Mo for the transition metals in(Fe_1/3Co_1/3Ni_1/3)₈₀(P_1/2B_1/2)₂₀0 HE-BMG on glass-forming ability?GFA?,thermal stability,mechanical properties,and corrosion resistance.Combined with fluxing purification treatment and J-quenching technology,we successfully prepare a series of(Fe_1/3Co_1/3Ni_1/3)_80-x-y0-x-y Cr_xMo_y(P_1/2B_1/2)₂₀?x=5,10;y=5,8?HE-BMGs with the maximum diameters of 1.0².5 mm.It shows that the addition of Cr results in the increase of the GFA of the alloy,and the addition of Mo reduces the GFA of the alloy.The compression test shows that when the addition of Cr leads to an increase in the compressive fracture strength and a slight decrease in the plastic strain of the alloy,and the addition of Mo results in a large reduction in both the compressive fracture strength and the plastic strain of the alloy.The potentiodynamic polarization curve test in 3.5 mass%NaCl solution shows that the corrosion resistance of the alloy increases with the increase of Cr content,and the addition of the proper amount of Mo leads to the enhancement of the corrosion resistance of the alloy but excessive addition of Mo causes deterioration of the corrosion resistance of the alloy.