Dynamic Response Behavior Of The Porous SiC/Ti-based Metallic Glass Composites

Although the ceramic armor exhibits excellent shock resistance,brittleness and low fracture toughness make the ceramic difficult to resist multi-hit.Bulk metallic glasses?BMGs?have excellent shock resistance due to ultrahigh strength,high hardness and large elastic strain.Combining the characteristics of the ceramic and the BMG as well as the advantage of the three-dimensional?3D?network structure,a new porous SiC/Ti-based metallic glass composite?Ti-BMGC?was prepared,which may have significant application prospect in the field of lightweight armor.To reveal the microstructure evolution and damage process of the Ti-BMGC,the dynamic mechanical properties,deformation and fracture characteristics of the Ti-BMGC were investigated by comparison with the Ti_32.8Zr_30.2Ni_5.3Cu₉Be_22.7 metallic glass?Ti-BMG?.Ballistic tests were performed to evaluate the shock resistance of the Ti-BMGC,and the anti-multi impact mechanism was discussed in detail.The results provide scientific guidance for the applicaiotn of the Ti-BMGC in the field of high velocity impact.The main research results are as follows:The unique 3D structure of the Ti-BMGC promoted homogeneous distribution for the metallic glass phase and the Si C phase.Shear band propagation in the metallic glass phase was totally confined by the SiC phase.Meanwhile,the initiation and propagation of cracks in the SiC phase were greatly confined by the metallic glass phase.The mutual reinforcement of the two phases in 3D directions improved the mechanical properties of the Ti-BMGC effectively.The Ti-BMGC exhibited positive strain rate sensitivity under both quasi-static and dynamic compressions,but negative strain rate sensitivity when the strain rate increased from quasi-static to dynamic compressions.The crack unstable propagation under dynamic compression was more severe than that under quasi-static compression,leading to the dynamic compression strength was lower than the quasi-static compression strength.To prevent the unstable propagation of the cracks could improve the dynamic mechanical properties of the Ti-BMGC effectively.Although dynamic compression induced more severe fracture than the quasi-static compression,the fracture mode was a mixture of shearing and axial splitting under both the two loading cases.The dynamic hardness of the Ti-BMGC was obviously greater than the static hardness.The brittleness parameter under dynamic indentation was also greater than that under static indentation.Although the dynamic indentation induced more severe deformation behavior than the static indentation,the deformation and fracture characteristics in the two loading cases were nearly the same,both exhibiting extensive cracks in the SiC phase and many shear bands in the metallic glass phase.Three different fracture regions were formed underneath the dynamic indentation,containing the severe deformation region close to the indentation tip,radial cracks propagation region underneath the severe deformation region,and slight deformation region far away from the indentation tip.The deformation characteristics under dynamic indentation were similar with that under ballistic impact,indicating that the dynamic indentation could be used as an effective measure to characterize the shock resistance.The Hugoniot elastic limit?HEL?and the spall strength of the Ti-BMG were estimated to be 5.34GPa and 3.61GPa,respectively,which were obviously greater than that of the traditional light crystalline metals.The microstructures of the Ti-BMG remained metallic glass under ballistic impact,meanwhile,the decrease of hardness was very low?⁸.8%?under ballistic impact.Thus,it played an important role to prepare the composite with excellent anti-multi impact property.The Ti-BMGC resisted 3 times of the ballistic impact,exhibiting excellent anti-multi impact property.The complete interface defeat was formed under the first ballistic impact.The projectile fracture,the elastic deformation of the Ti-BMGC,and the stress wave attenuation were the main energy dissipation processes during interface defeat.The projectile penetrated the Ti-BMGC under the subsequent ballistic impact due to the decrease of the capacity of dwelling energy.In this case,the energy dissipated not only through the interface defeat but also through the fracture,fragments splash of the Ti-BMGC,and the erosion of projectile.