Study On Properties Of FeCoNi-based Soft Magnetic High Entropy Amorphous Alloys And Their Corresponding High Entropy Alloys

New FeCoNi-based soft magnetic high entropy amorphous alloys?HEAAs?was developed by replacing Fe elements in Fe₈₀Si₉B₁₁ amorphous alloy with Co and Ni elements.In addition,the FeCoNi-based high entropy alloys?HEAs?with the same chemical compositions was prepared.The microstructure of FeCoNi-based soft magnetic HEAAs was detected by X ray diffraction?XRD?,transmission electron microscopy?TEM?and high-resolution transmission electron microscopy?HRTEM?.The thermodynamic stability of the alloys was examined by differential scanning calorimetry?DSC?.The Bs,Hc and magnetic permeability ?i of the alloys were tested by vibrating sample magnetometer?VSM?,AC B-H hysteresiscope and impedance analyzer.The compressive mechanical properties of HEAs were tested by electronic universal testing machine.This work provides a new perspective for the future development of the HEAAs and HEAs with excellent comprehensive performance.The main research work and conclusions in this thesis are as follows:?1?Nano scale FCC phase embedded in the amorphous matrix in the Fe_26.7Co_26.7Ni_26.6Si9B₁₁,Fe₃₀Co₂₅Ni₂₅Si₉B₁₁ alloy.The Fe₄₀Co₂₀Ni₂₀Si₉B₁₁ alloy has a completely amorphous structure.?2?The FeCoNi-based HEAAs shows excellent soft magnetic properties.For example,Fe_26.7Co_26.7Ni_26.6Si₉B₁₁ HEAA has lower Hc?2 A/m?and high Bs?1.07 T?.The FeCoNi-based HEAs also shows typical soft magnetic properties.?3?The FeCoNi-based HEAAs have good flexural toughness even after stress-relief annealing.The FeCoNi-based HEAs also shows high strength and good compressive plasticity.?4?The FeCoNi-based HEAAs shows phase transition from FCC to BCC phase after high-temperature crystallization annealing,and the crystallization products of amorphous phase in the matrix is a high entropy BCC phase instead of brittle intermetallic phases.