Molecular dynamics simulation of Ti-6AL-4V diffusion bonding behavior under different process parameters

In this paper the diffusion-bonding process of a titanium alloy was investigated in detail using molecular dynamics.The protocell model of a Ti-6Al-4V alloy was obtained by the atomic random substitution method.The mixed potential function method, EAM (Embedded Atom Method) and Morse potential was used to deal with the Ti-Al-V ternary alloy system.And the diffusion bonding process of Ti-6Al-4V was simulated numerically.The influence of temperature, pressure and holding time on the diffusion bonding behavior of Ti-6Al-4V alloys was studied.The results showed that an increase of the temperature, pressure and holding time can improve the diffusion of interfacial atoms and increase the diffusion bonding width.In addition, the diffusion temperature has a critical value, i.e., 1100 K.When the temperature is lower than 1100 K, the interface atoms hardly diffuse.The MSD (Mean Square Deviation) vs. t curves of Ti, Al and V atoms at different temperatures were established.The diffusion coefficients of Ti, Al and V atoms at different temperatures were obtained by the relationship between the MSD and the atomic diffusion coefficient, after which the Arrhenius equations of the diffusion coefficient were obtained, respectively.Based on the diffusion coefficient equation, the diffusion activation energies of each element were deduced.Compared with the experimental data, the rationality of the simulation results was verified.