Study On Static-dynamic Mechanical Properties Of Bonding Interface Of Ti/Al Explosive Welding

Ti-Al layered composites prepared by explosive welding process have both the advantages of Ti and Al,and have excellent properties such as high strength,light weight and corrosion resistance,and have been widely used in aerospace,transportation,pressure vessels and other fields.The bonding interface of Ti-Al layered composites is the transitional region of composition,microstructure and properties,which determines the feasibility of explosion process and the reliability of service.During the service process,Ti-Al layered composites will inevitably be affected by external loads in different directions and positions,so the mechanical properties of the interface region are extremely important.Therefore,by studying the static dynamic mechanical properties of Ti-Al layered composites in different bonding interface regions,this paper can not only provide a reference for optimizing the preparation process of Ti-Al layered composites,but also has great significance for practical engineering applications.The specific findings of the study are as follows:（1）Ti-Al layered composites were prepared by explosive welding process,and the microstructure of the bonding interface region was observed.The results show that the morphology of bonding interface is composed of continuous straight lines and waveforms,with asymmetric distribution.There are a few"elephant trunk-like"structures,black voids and"island-like"melts near the interface.Interdiffusion of elements exists at the bonding interface,and the thickness of the diffusion zone is about 2μm.The non-metallic elements are evenly distributed in the component material without agglomeration,which indicates that there is no oxide formation.Affected by the diffusion rate,the content of aluminum in the molten region is obviously higher than that of titanium.The smooth region of the melt is dominated by Ti Al₃metal compounds,while the irregular region is dominated by other intermetallic compounds,and with the decrease of the distance close to the bonding interface,the hardness value and elastic modulus gradually increased,and the increasing trend is more obvious on the Al side.（2）The static-dynamic mechanical properties of Ti-Al layered composites with different bonding interface regions were studied.The results show that:the Ti-Al layered composites exhibit good plasticity and no fracture failure during static and dynamic compression.The true stress-strain curve of the parallel structure 1:4 shows ideal elastoplasticity,while the other types show bilinear plasticity strengthening.With the decrease of the ratio of Ti to Al,the yield strength of layered composites shows a downward trend,which basically meets the rule of mixture.At the same time,it is shows that the Ti layer is the main stress layer during the compression process.The Ti-Al layered composite material has a certain strain rate strengthening effect,and the yield strength increases with the increase of the strain rate.Under the dynamic impact,the Ti-Al layered composites have obvious strain rate plasticization effect.With the increase of strain rate,the plastic stage increases significantly,and the parallel ratio of2:3 shows more excellent plastic characteristics.Based on the true stress-strain curve of static dynamic compression,the dynamic constitutive relationship is established by J-C constitutive equations,which fits well with the experimental values.（3）The strain distribution and evolution of Ti-Al layered composites with different bonding interface regions during the compression process were studied.The results showed that the transfer and redistribution of strain are the main reasons for the excellent plasticity of Ti-Al layered composites.The typical strain evolution process of the parallel structures:Strain localization occurs preferentially in Ti layer,and the bonding interface of layered structure transfers strain to Al layer,and strain localization occurs in Al layer.Under the same strain,the time delay responses of the parallel structures at different positions are different.Layered strain bands appear in series structures and the maximum strain appears near the interface,which is related to the microstructure.