Molecular dynamics study on diffusion welding technology of PCHE

The titanium alloy diffusion bonding structure is widely used in aviation manufacturing because of its good welding quality and small stress deformation. The diffusion bonding process parameters determine the diffusion bonding quality of the titanium alloy, which determines the mechanical properties of the diffusion joint. In this paper, molecular dynamics simulation is used to study the diffusion bonding process of titanium alloy, the random replacement method was used to obtain the initial configuration of the corresponding atomic percentage. The Nose-Hoover temperature control method and Parrinello-Rahman pressure control method were applied to simulate the diffusion bonding process of titanium alloy under different conditions. The atom concentration distribution under various conditions was obtained using Matlab programming. The change rule of diffusion connection width with process parameters was also analyzed. Finally, the tensile deformation behavior of titanium alloy diffusion joint was simulated to obtain the stress-strain curves under different technological parameters. The results show that the holding temperature, holding time, and welding pressure influence the quality of diffusion welding. The higher the holding temperature; the larger the width of the welding diffusion layer. The longer the holding time, the greater the thickness of the welding diffusion layer. The greater the welding pressure, the wider the diffusion welding layer. The tensile tests on the welded joints and the base material show that the tensile mechanical properties of the diffusion joint can be comparable to the base material under the appropriate welding process parameters.