The Preparation And Study On The Mechanical Properties Of Ti-Based Amorphous Composites Toughening By Pure Copper

Ti-based amorphous alloys have extremely high strength,low elastic modulus,and excellent corrosion resistance,which show a broad application prospect as the implanting materials.However,their low glass formation ability and brittleness at room temperature limit their use in practice.In consequence,in the present thesis,the powder of a non-toxic Ti-based alloy,Ti₆₀Zr₁₀Ta₁₅Si₁₅,was prepared in the amorphous phase by ball milling method.The powders were coated with pure copper by the electroless plating method and then consolidated into the copper toughened Ti-based amorphous matrix composite by spark plasma sintering?SPS?method.The microstructure and mechanical properties of the composite were characterized,and the deformation mechanism of the composite was discussed.The main contents and results are as follows:1.The amorphous Ti₆₀Zr₁₀Ta₁₅Si₁₅ powder was prepared by the ball milling technique using a stoichiometric amount of Ti,Zr,Ta and Si powder with purities of99.9%or greater as starting materials.The effects of the process parameters on the amorphization process of the mixed powders were investigated.The results indicated that under the conditions of the ratio of ball to the material of 20:1 and the rotation speed of 230 rpm,the fully amorphous powders can be obtained after ball milled for35 h.2.The copper toughed Ti amorphous powders were successfully coated with a pure copper layer by electroless plating method,and the process parameters of the electroless plating were optimized.It is found that,under the conditions of the main salt?CuSO4?concentration in the plating bath of 27 g/L,and plating temperature of70°C,a copper plating with high quality can be obtained on the surface of the amorphous powders.The copper plating is tightly bonded with the particles with a uniform thickness.3.The copper toughened titanium-based amorphous matrix composites were successfully prepared by SPS method,and the effects of the sintering parameters on the microstructures and the mechanical properties were investigated.It is found that,under the conditions of the temperature of 770 K and the pressure of 400 MPa,the almost fully dense composite can be obtained.The density of the composite is about99%,and the copper in the composite is in the three-dimensional mesh structure with the amorphous phase mosaicing in the grid.The composite exhibits an extremely high compression strength,which reaches 1750 MPa,with some plasticity.4.The deformation mechanisms of the composite were investigated.It is found that the deformation firstly occurred in the copper,and the copper in the three-dimensional mesh structure can effectively obstruct the expansion of shear bands in the amorphous phases,and consequently induce the formation of new shear bands,which is conducive to the improvement of the plasticity of the composite.With the increase of the copper content,the strength of the composite decreases while the plasticity increases.