Preparation And Mechanical Properties Of SiC/Zr-based Metallic Glass Composites

Metallic glass have been studied extensively in recent years because of their unique physical,chemical,and mechanical properties.SiC is an excellent composite reinforced phase with low density,high hardness,high strength,low thermal expansion coefficient,strong heat transfer ability and stable property at high temperature.Therefore,in order to reduce the density of metallic glass,improve the comprehensive mechanical properties and expand its application areas,the porous SiC preform is added as the second phase.The porous SiC/Zr_41.2Ti_13.8Ni_10.0Cu_12.5Be_22.5 metallic glass interpenetrating phase composites were fabricated by pressure-infiltration-quenching method in this paper.The microstructure and mechanical behavior of the composites were characterized and analyzed by OM,XRD,DSC,SEM,room temperature quasi-static compression test,Hopkinson pressure bar test and room temperature dry friction test.According to the thermodynamic parameters of Zr_41.2Ti_13.8Ni_10.0Cu_12.5Be_22.5 metallic glass was decreased by the addition of SiC foam.Under different infiltration temperature,the composite material is composed of SiC phase and metallic glass phase.There is no crystallization phenomenon in the metallic glass.And the interface between the SiC preform and the metallic glass matrix is well bonded,and there are no defects such as holes,cracks,etc.The interface analysis shows that there is a mutual diffusion layer between the SiC preform and the metallic glass matrix.When the infiltration temperature is 820?,the thickness of the diffusion layer is 2?m,when the infiltration temperature is 840 ? the thickness is 3?m,when the infiltration temperature is 860? the thickness is 4?m.The products of the interfacial reaction are ZrC and TiC.The infiltration temperature does not affect the quasi-static compressive properties of the composites.The effect of pore density of SiC.foam preform on the microstructure and quasi-static mechanical properties of the composites was further investigated.The results show that the composites with different pore density are composed of SiC and metallic glass.The pore size of the composites with different pore density is significantly different.The pore size is the largest when the pore density of the composite is 40ppi,and the pore size is the smallest when the pore density is 60ppi.The greater the pore density of the SiC preform,the higher the strength of the composites.The fracture mode of the composites is shear fracture,and the shear fracture angle is about 40°.SiC phase shows the intergranular fracture characteristics and metallic glass phase exhibits the typical characteristics of viscous flow.Mainly to the"river like" pattern,in addition to the existence of a thick and orderly "multiple ridges" pattern and the formation of the molten droplet morphology.The SiC skeleton/Zr_41.2Ti_13.8Ni_10.0Cu_12.5Be_22.5 metallic glass composites with higher volume fraction of SiC were prepared by pressure-infiltration-quenching method.The thermodynamic properties,microstructure,dynamic compressive behavior at room temperature and the friction behavior of dry friction at room temperature were analyzed.The results show that the thermodynamic stability of the metallic glass in the composites was decreased by the addition of SiC skeleton.The metallic glass is completely filled in the pores of the SiC framework.The interface between the two phases is well bonded.Elastic deformation occurs under the condition of dynamic loading,and there is no yielding and plastic deformation.The dynamic compressive strength decreases with the increase of strain rate,and the performance of the dynamic compressive strength is negative strain rate sensitivity.SiC phase shows the cleavage fracture characteristics and metallic glass phase exhibits the typical characteristics of viscous flow.The friction coefficient of the composite material with ZrO2 is about 0.3-0.5.The change of normal load has little effect on friction coefficient.With the increase of normal load,the wear marks become deeper and the wear mechanism of composites changed from abrasive wear to adhesive wear.