Effects Of Alloying Elements Addition On Glass-forming Ability,Soft Magnetic Property And Mechanical Property Of Fe-based Amorphous Alloys

Due to the long-range disordered and short-range ordered microstructure of amorphous alloys,they exhibit much better mechanical properties compared with those traditional crystalline counterparts.Among them,Fe-based ferromagetic bulk metallic glasses?BMG?have attracted both scientific and industrial interest because of their high strength,excellent soft magnetic properties and low costs.However,the limited glass forming ability?GFA?and room-temperature hinders their widespread as structural and magnetic functional materials.Therefore,it is of great significance to develop a new Fe-based BMG with high GFA,great soft magnetic property and large room temperature compressive plasticity.Via the component design principle of similar elements substitution and atomic size adjustment,Fe₅₆Ni₂₀Mo₄P₁₂C₄B₄ and Fe₅₆Ni₂₀Mo₄P₁₁C₄B₄Si₁ BMG were successfully developed,which combine high GFA,excellent soft magnetic properties and large plasticity.This work has lead a new access to designing soft-magnetic Fe-based amorphous alloys,and at the same time,can be a solid support for the mechanism of the influence on BMG by component adjustment.Main researches include:?1?Through the addition of Ni element,amorphous ribbons and rods were successfully prepared with the composition of Fe_76-xNi_xMo₄P₁₂C₄B₄?x=0,10,15,17.5,20,22.5,25 at.%?.Moreover,the influence after this addition on the GFA,thermal properties,magnetic properties and mechanical properties.The experiment results reveal that with the increase of Ni content,the glass transition temperature T_g has decreased,accompanying an increase in the supercooled liquid region?T_x,resulting in the improvement of thermal stability.Although the saturation magnetization Bs has slightly decreased,the coercive force H_c declined,namely the soft magnetic properties have been improved.In the meantime,the BMG exhibit high plasticity at room temperature.?2?The metalloid element Si with small atomic size has been added into the former BMG and developed two new BMGs:Fe_56-xNi₂₀Mo₄P₁₂C₄B₄Si_x?x=1,2,3,4,5 at.%?and Fe₅₆Ni₂₀Mo₄P_12-xC₄B₄Si_x?x=1,2,3,4,5 at.%?.In the latter BMG,the addition of Si element has improved its GFA and raised the diameters of amorphous cylinders from 1.5 mm to 2.0mm by copper mold casting method.Furthermore,the saturation magnetization,compressive strength and plasticity have been optimized simultaneously.?3?The deformation mechanism has changed after the addition of Ni and Si elements.The study of SEM about the fracture morphologies of deformed specimen showed that the propagation of shear bands has substituted the brittle mirror-like regions.Especially,after the Si addition,multiple shear bands of different directions were observed,leading to the improved plasticity of 7%.?4?Under the guidance of BMG design principle,through the element addition and component adjustment,this paper has successfully developed a new Fe-based BMG with high GFA?diameters up to 2 mm?,excellent soft magnetic properties?high saturation magnetization B_s of 0.94 T and low coercive force of 2 A/m?,as well as high yield strength and rather high plasticity of 7%.It can be seen that this new Fe-based BMG has a promising application value as structural and magnetic functional materials.