Study On Interface Micromechanical Properties Of Ti/TiAl₃ Laminated Composites

Ti/TiAl₃ laminated composite materials have advantages such as low density,high specific strength,and high-temperature oxidation resistance,and are widely used in lightweight new armor protection and aerospace fields.The common preparation methods of intermetallic compounds are hot pressing and hot rolling.However,due to the disadvantages of not being able to prepare large size and not suitable for preparation during the preparation process,explosive welding is widely used because of its advantages of simple operation,convenient preparation,and adjustable size.In this paper,Ti/TiAl₃ laminated composites were prepared by the method of"Explosive welding+Heat treatment",and the tensile microstructure,mechanical properties and fracture microstructure were analyzed and discussed;The atomic structure changes of Ti/TiAl₃ laminated composites under tension,compression and shear were observed by molecular dynamics.The research results found that:The stretching process of Ti/TiAl₃ laminated composite material was observed through molecular dynamics simulation and in-situ stretching methods.Comparing the stretching processes obtained by the two methods,it was found that:the strain increased,cracks first appeared in the TiAl₃ layer.When the cracks in the TiAl₃ layer became larger holes,deformation occurred in the adjacent Ti layer near the holes,and cracks gradually appeared before breaking,and the Ti layer in the middle layer broke later,The trend change process shown by the simulation results and experimental results is consistent.And the tensile fracture surface was observed by SEM,indicating that the fracture mode of the Ti layer is ductile fracture,and the fracture type is dimple port;The fracture mode of TiAl₃ layer is brittle fracture,and the fracture types are intergranular fracture and transgranular fracture.Molecular dynamics simulation was used to simulate the tensile behavior of Ti/TiAl₃ at different strain rates,temperatures,and TiAl₃ thicknesses.The results showed that the higher the strain rate,the higher the tensile strength,tensile rate,elastic limit,and other numerical values.The higher the temperature at the same strain rate,the lower the tensile strength,tensile rate,and elastic limit,but the temperature has little effect on the elastic modulus.After reducing the thickness of the TiAl₃ layer by half,it was found that the elastic modulus of the Ti/TiAl₃ laminated composite material decreased by about 35%,the tensile strength decreased by about 50%,and the elongation decreased by about 44%.Using molecular dynamics simulation method,compression and shear simulations were conducted on Ti/TiAl₃ under different strain rates and thicknesses of TiAl₃ layers.The results showed that when the thickness of TiAl₃ layer was reduced by half,the compressive modulus of the 5-layer Ti/TiAl₃ laminated composite material decreased by about 27%,compressive strength decreased by about 74%,and shear resistance decreased by 66%.The change in compression rate has little effect on the compression modulus of Ti/TiAl₃,but the compressive strength increases with the increase of strain rate.At a compression rate of 5?/ps,the compressive strength of Ti/TiAl₃ increases by 43%,while at a compression rate of10?/ps,the compressive strength of Ti/TiAl₃ increases by 133%.The shear strength of the Ti/TiAl₃ model also increases with the increase of the shear rate.At the same time,the curve under 5?/ps shear is similar to that under 10?/ps shear.It is found that when the shear rate reaches a certain value,its shear strength is less affected by the shear strain rate.