Study On The Structure And Properties Of Fe-based Medium Entropy And Amorphous Alloys Prepared From Industrial-grade Raw Materials

The medium and high entropy alloys and amorphous alloys obtained by order/entropy control design break the traditional design concept of alloys and make continuous breakthroughs in properties,which has important theoretical research significance and industrial application potential.In this paper,metastable alloys with excellent mechanical and magnetic properties were prepared from industrial grade raw materials by flux coating method and magnetic levitation melting water-cooled copper mold vacuum suction casting method.The effects of different basicity coating agents on impurity removal effect,microstructure and mechanical properties of amorphous composites were investigated,and rare earth elements(Ce,Dy)were added to explore the mechanical properties and soft magnetic properties of amorphous composites performance optimization.Finally,the effects of Ag and Cu Microalloying on the microstructure,mechanical properties and magnetic properties of the alloy were investigated.The results show that Fe_61.5Mn_14.3Si_9.3Cr₁₄C_0.9(at.%)Amorphous Composites with high strength and toughness were prepared by using industrial grade raw materials(Q235 steel,Fe-Cr alloy)and coating agent to remove phosphorus and sulfur impurities in the alloy.The alloy is composed of fcc(?)phase,bcc phase and amorphous phase.By changing the basicity of the coating agent R(R=0,2,3,4,5,6),the optimum conditions are as follows:R=4(Cao:Fe₂O₃:Si O₂ is 4:5:1),the removal rate of phosphorus and sulfur reaches 99.053%and 98.396%respectively.With the increase of R,the fracture strength and plastic strain of the alloy increase first and then decrease.When R=4,the comprehensive mechanical properties are the best.The room temperature fracture strength and compression plasticity are as high as 5539.82 MPa and 53.45%,respectively.Fe_61.5Mn_14.3Si_9.3Cr₁₄C_0.9(at.%)Amorphous Composites with high strength and toughness were prepared by purifying industrial raw materials with ternary coating agent.The effects of Microalloying on the mechanical and magnetic properties of(Fe_61.5Mn_14.3Si_9.3Cr₁₄C_0.9)_99.6RE_0.4(RE=Ce?Dy,at.%)alloys were studied.The microstructure of the alloy system is amorphous phase,fcc(?)phase and bcc phase.With the addition of rare earth elements,the mechanical properties of(Fe_61.5Mn_14.3Si_9.3Cr₁₄C_0.9)_99.6Ce_0.4 alloy are optimized.The fracture strength and plastic deformation of(Fe_61.5Mn_14.3Si_9.3Cr₁₄C_0.9)_99.6Ce_0.4 alloy are 5746.85 MPa and 59.52%respectively.Moreover,the addition of rare earth elements can reduce the coercivity of the alloy and improve the saturation magnetization,showing excellent soft magnetism,and the effect of light rare earth elements is more significant.The medium entropy alloy Fe_63.3Mn₁₄Si_9.1Cr_9.8C_3.8(at.%)prepared from industrial raw materials was microalloyed by adding a small amount of Ag and Cu.The effect of stacking fault energy on the microstructure,mechanical and magnetic properties of the alloy system was studied.The results show that the Fe_63.3Mn₁₄Si_9.1Cr_9.8C_3.8 medium entropy alloy has a single fcc structure.The addition of Ag and Cu further reduces the stacking fault and refines the grain size,resulting in the decrease of yield strength and the increase of fracture strength and plasticity.The fracture strength and plastic deformation of(Fe_63.3Mn₁₄Si_9.1Cr_9.8C_3.8)_99.6Cu_0.4 reached 2434.69 MPa and 22.23%respectively,and the relative permeability was as low as 1.00013,showing excellent mechanical properties and paramagnetism.