Study On Diffusion Behavior Of Ti-Fe Solid-State Shear Joint Interface

Solid-state shear connection technology is one of solid-state methods,which has the advantages of high-efficiency,simpleness and speediness.It can be applied to the connection processing of the homogeneous or heterogeneous metals.In this paper,the solid-state shear connection experiments of titanium and iron were implemented using differtent deformation degree,cooling method and temperature by the variable control method.The interface behavior and formation mechanism of the Ti-Fe connection interface were explored by experimental study and theoretical analysis.In this paper,the shear connection interfaces of Ti-Fe were observed and analyzed by Zeiss microscope,scanning electron microscope,energy spectrometer,X-ray diffraction analyzer and transmission electron microscope.The research results showed that metallurgical bonding of Ti-Fe can be reached by shear connection.The interdiffusion of atoms occur during the shearing process,and a new strip structure with a certain thickness generate at the interface.The phases of the new structure are intermetallic compounds of Fe Ti and Fe₂Ti.A large number of dislocations are observed near the Ti-Fe connection area and inside the grains.The high-density dislocations can provide channels for the diffusion of Ti and Fe atoms.Based on Miedema theory and Fick's second law,the thermodynamics of Ti-Fe binary alloy and the kinetics of the diffusion of Ti-Fe shear connection wew analysed respectively.Thermodynamic analysis showed that the values of formation enthalpy and Gibbs free energy of Fe Ti and Fe₂Ti are equal,which are-24.553 k J/mol and-22.546 k J/mol respectively,they can meet the thermodynamic precipitation conditions of intermetallic compounded Fe Ti and Fe₂Ti.That is consistent with the phase analysis results of connection interface of Ti-Fe.Dynamic analysis shows that Ti-Fe interdiffusion can occur under all experimental conditions,which can meet the kinetic conditions of new phase precipitation.Large plastic deformation of Ti and Fe occurs,during the solid-state shear connection process of Ti-Fe,at the same time,Ti and Fe atoms begin to diffuse and migrate by means of grain boundary diffusion and dislocation diffusion.In order to study the influence of deformation and temperature,the shear connection interfaces of Ti-Fe were observed and analyzed by Zeiss microscope,scanning electron microscope,energy spectrometer,and the kinetics of the diffusion.The research results showed that the grain size becomes smaller and the grain boundary increases as the amount of deformation increases,at the same time,a large number of dislocations appear near the Ti-Fe connection area and inside the grains.So that the diffusion coefficients and the interdiffusion distance of Ti and Fe at the interface increase significantly.The grain size,the diffusion coefficient and the interdiffusion distance of atoms also increase,as the temperature increases.However,compared with the deformation,the effect of the temperature on the shear connection interface of Fe-Ti is latter.