Study On Mechanical Properties And Thermal Stability Of Pseudo-High Entropy Zr-Based Bulk Amorphous Alloys

Due to the long-range disordered atomic structure,bulk amorphous alloys have better mechanical properties than traditional alloys,including high strength and large plastic strain capacity,and have been extensively studied by scholars at home and abroad.Among them,the zirconium-based bulk bulk amorphous alloy is famous for its excellent mechanical properties and thermal stability.In this paper,a series of pseudo-high-entropy zirconium-based bulk amorphous alloys were designed and prepared by the similar element substitution method,and the relationship between their mechanical properties and thermal stability and the replacement elements was explored.This article is based on Zr₅₅Al₁₀Ni₅Cu₃₀ amorphous alloy,through similar element replacement method and composition adjustment technology,The Zr Al(Ni,Ag,Fe,Nb)Cu pseudo-high-entropy zirconium-based bulk amorphous alloy system with large amorphous forming ability,good thermal stability and mechanical properties were prepared.Using XRD,DSC,SEM,TEM and other advanced experimental methods,exploring the relationship between the good mechanical properties and thermal stability of zirconium-based amorphous alloys and the introduction of positive mixing enthalpy atom pairs provides a new idea for exploring the preparation of high-performance pseudo-high-entropy zirconium-based bulk amorphous alloys.The main work and conclusions of this paper are summarized as follows:1.Based on the Zr₅₅Al₁₀Ni₅Cu₃₀ amorphous alloy system,Zr₅₅Al₁₀Ni₅Cu₂₅Ag₅(1720 MPa,9.8%,85 K),Zr₅₅Al₁₀Fe₅Cu₃₀(1785 MPa,7.9%,95 K),Zr₅₅Al₁₀Nb₅Cu₃₀(1563 MPa,9.5%,48 K)pseudo-high-entropy amorphous alloy rods with a diameter of 2mm with good thermal stability and mechanical properties(compressive strength,plastic strain,supercooled liquid region)are prepared by the method of replacing similar elements.The addition of Ag and Fe reduces the binding force between the elements,making the internal structure more loose,providing more nucleation sites that can form the shear transformation zone,and forming multiple shear bands in the compression deformation process,which ultimately optimizes the plastic strain capacity of the alloy.2.Based on the above experiments,through component adjustment,Zr₅₅Al₁₀Fe₁₀Cu₂₅(1799 MPa,8.3%,81 K),Zr₆₀Al₁₀Fe₈Cu₁₈Ag₄(1684 MPa,9.2%,84 K),Zr₆₈Al_8.5Fe₈Cu₁₂Ag_3.5(1440 MPa,9.8%,52 K)pseudo-high-entropy amorphous alloy rods with a diameter of 2mm with good thermal stability and mechanical properties(compressive strength,plastic strain,supercooled liquid region)are prepared.3.The prepared Zr₄₈Al₁₀M₅Cu₃₇(M=Ag or Fe)pseudo-high entropy amorphous alloy ribbons containing Al₇Cu₁₆Zr₆(APC,Approximant Crystal)phase has good ductility and can be simply bent at 180°without fracture.The reason may be related to the precipitation of Al₅Cu₇Zr(bcc)phase.When the cooling rate is not less than a certain degree,some Al₅Cu₇Zr(bcc)phase cannot be transformed into Al₇Cu₁₆Zr₆(fcc)phase with larger lattice constant,and Al₅Cu₇Zr(bcc)phase can exist in a certain proportion.Different crystal structures participate in the deformation process in different response ways,resulting in multiple shear bands in the deformation process,enhancing the stability of the shear band and delaying its expansion,thus optimizing the bending ductility of the ribbon.