Mechanical Properties And Tensile Deformation Mechanism Of Cu-Zr-Ti-RE Metallic Microfibers

Metallic micro-fibers exhibit the special mechanical properties due to their unique microstructure and geometrical features,and are characterized by both metallic fibers and amorphous alloys.In this paper,the Cu-Zr-Ti-RE series metallic fibers were prepared by rotated dipping process and then the influences of the doping of rare earth elements?Pr,Y and Dy?on the structure,the tensile mechanical properties and the fracture reliability of Cu-Zr-Ti metallic fibers were investigated systematically.Based on this,the tensile deformation mechanism of amorphous metallic fibers is accordingly discussed.The microstructure of the as-prepared Cu-Zr-Ti-RE series metallic fibers was characterized by XRD,DSC,SEM and TEM,respectively.The Video Gauge^TM in-situ quasi-static tensile test platform was used to measure the mechanical properties of as-prepared and current-modulated Cu-Zr-Ti-RE series metallic fibers,meanwhile,the fracture reliability of which were analysed by Weibull statistical method.The ANSYS finite element simulation and fracture morphology observation method were used to analyze the tensile deformation process of metallic fibers,to further elaborate its deformation mechanism.The experimental results show that the as-prepared Cu-Zr-Ti-RE metallic fibers are typical amorphous state.The doping of traces of rare earth can improve the thermal stability of metallic fibers,and among which,the glass transition temperature?T_g?of Cu-Zr-Ti-Pr fibers can reach at 450.8?.Rare-earth doping increases the degree of structure order???of metallic fibers,and a certain number of ordered regions of nanoclusters appears in the amorphous matrix,which is the direct cause of the improvement of the mechanical properties of the metallic fibers.The doping of rare earth increases the tensile strength?R_m?and the breaking elongation?e?as well,among which,the R_m of Cu-Zr-Ti-Dy fibers is 2813.8 MPa?2.81 GPa?,and the e of Cu-Zr-Ti-Pr fibers is2.85%.The doping of rare earth is also beneficial to enhance the fracture reliability of Cu-based metallic fibers,among which,the three-parameter Weibull modulus?m?of Cu-Zr-Ti-Dy fibers is 2.69,and the breaking threshold??_u?of Cu-Zr-Ti-Pr fibers can reach at 1420.37 MPa?1.42 GPa?.As a result,the rare-earth dopping can provide technical support for the practical engineering applications of Cu-based metallic fibers.Based on ANSYS/LS-DYNA finite element model and uniaxial tensile simulation,the tensile deformation process of Cu-based metallic fibers tend to comply with the Drucker-Prager yield criterion.The tensile fracture morphology of Cu-Zr-Ti-RE series metallic fibers indicate that the Cu-based amorphous metallic fibers are plastically fractured in microstructure for exisiting large number of shear bands?macroscopically are still brittle fracture characteristics?.The doping of rare earth makes the fracture morphology of the fibers more complicated and the fracture angles???increase.Among which,the?of Cu-Zr-Ti-Y fiber is about 52°.During the process of tensile deformation of metallic fibers,the initial is elastic deformation,and then the free volume gathered and rheological defects fused to form initial cracks.New micropores are formed in the plastic zone at the front end of the crack and local shear deformation occurs.Continued loading causes the shear bands to expand rapidly and eventually breaks.