Preparation And Processing Optimization Of Bimetals Composed Of Ti Alloy And Ti₄₃Zr₂₇Mo₅Cu₁₀Be₁₅ Metallic Glasses Composites

In this thesis,the bimetals composed of Ti-based amorphous composite and Ti alloy were prepared by using TC4,TB2 and TA5 as substrates respectively.As far the process of the preparation was concerned,optimizated method was explored to increase the depostion efficiency.To evaluating the porperties of the as-produced bimetals,microstructure observation and tensile deformation test of bimetals revealed several features between Ti-based metallic glass composite and Ti alloy.Theoretical calculation was also deduced to explain and understand the homogeneous deformation and the necking phenomenon of bimetals of Ti alloy and Ti₄₃Zr₂₇Mo₅Cu₁₀Be_15.Argon arc with tungsten electrode was used to prepare bimetals with composites of TC4/Ti₄₃Zr₂₇Mo₅Cu₁₀Be₁₅,TB2/Ti₄₃Zr₂₇Mo₅Cu₁₀Be₁₅5 and TA5/Ti₄₃Zr₂₇Mo₅Cu₁₀Be₁₅.When the current value is 200A,the bimetals has good metallurgical bonding.In this parameter,the region of Ti₄₃Zr₂₇Mo₅Cu₁₀Be₁₅5 still shows a mixture microstructure of amorphous and crystalline phases on the Ti alloy plate of the bimetals,the volume fraction ofβdendrite is the same as that of single Ti₄₃Zr₂₇Mo₅Cu₁₀Be₁₅,which is about 62%.In the process of cladding and deposition,optimized methods were used to obtain Ti₄₃Zr₂₇Mo₅Cu₁₀Be₁₅5 lamella.Suction casting with copper mould was replaced by wire electrode cutting on ingot,which can increase the efficiency of preparation.Analyzing the microstructure and mechanical properties of the bimetals reveals that in the region of Ti₄₃Zr₂₇Mo₅Cu₁₀Be₁₅,βdendrites are dispersively distributed in the amorphous matrix.The thickness of theβdiffusion layer is 6μm.TC4/Ti₄₃Zr₂₇Mo₅Cu₁₀Be₁₅5 and TB2/Ti₄₃Zr₂₇Mo₅Cu₁₀Be₁₅5 biemtals both exhibits the advantages of Ti alloy and amorphous alloy composite,especially TC4/Ti₄₃Zr₂₇Mo₅Cu₁₀Be₁₅.However,TA5/Ti₄₃Zr₂₇Mo₅Cu₁₀Be₁₅does not show excellent plasticity.Obviously,amorphous alloy composite is sensitive to the strength of the Ti alloy substrates.So if Ti₄₃Zr₂₇Mo₅Cu₁₀Be₁₅5 amorphous alloy composite is confined with high strength and ductility Ti alloy,it will be exhibiting better mechanical property.There are normalized strain-hardening rate and relevant equations for bimetal by calculation.When strain-hardening rate less than critical value one,the bimetal tends to localize deformation necking.When strain-hardening rate above one,the bimetal has homogeneous deformation ability.Although the strain-hardening rate of Ti₄₃Zr₂₇Mo₅Cu₁₀Be₁₅is less than one,bimetal tensile deformation is homogeneous.Theoretical calculation has verifying experimental results.Moerover,whether occur homogeneous or not,it is also related to the volume fraction of amorphous alloy composite in the bimetal,which is called the size effect.So if improving the ability of homogeneous deformation,there has several measures:increasing the normalized strain-hardening rate of amorphous alloy composite and crystalline metal respectively.High strength and ductility crystalline metal can improve the homogeneous deformation.In the bimetal,larger the volume fraction of crystalline metal,more homogeneous the deformation.