Molecular Dynamics Simulation Of Anisotropy On Deformation Mechanism Of Titanium

In recent years,titanium metal has been widely used in various fields due to its good performance in performance,and its plastic deformation mechanism has always been a hot topic for people to study.Titanium is a densely packed hexagonal crystal structure at room temperature,and the symmetry is relatively low,so it shows obvious anisotropy.In this paper,molecular dynamics methods were used to study the plastic deformation mechanism of metal titanium under different loading conditions.In this paper,different molecular dynamics models of tensile deformation with three different tensile directions have been established,and the embedded atomic potential developed by Ackland in 1992 is used to study the influence of different loading directions on the deformation process.The results of the analysis of the stress-strain curve show that at a temperature of 300K and a strain rate of 10~8^-1,titanium metal contains elastic stage,yield stage,necking stage and fracture stage in the deformation process of tension applied along the crystal direction[0001]?[01(?)0]?and[10(?)2].When tension applied along the crystal direction[0001],the system begins to yield at a strain of around 0.065 and the yield stress is 5.49 GPa.The yield stress and strain along the[10(?)2]crystalline tension were 3.22 GPa and 0.047.Which is lower than loading along[0001]direction.The lowest condition is tension along[01(?)0],its yield stress is 2.82 GPa,the strain at this time is 0.042.The OVITO visualization method is used to analyze the microscopic deformation mechanisms such as dislocation slip and twin generated during loading.The results show that(10(?)2)twins are obtained in the process of tension along the crystal direction[0001],and the binding force analysis and Schmid factor calculations lead to the conclusion that(10(?)2)twins are formed by the combination of slip and recombination mechanisms.The main deformation method when tension along the[01(?)0]crystal direction is the slip of the cylinder.When tension along the[10(?)2]crystal direction,the main deformation method is the twinlike stacking fault caused by the Shockley₂ partial dislocation of the base surface,which then evolves into titanium with FCC structure with lattice distortion.In addition,by calculating the generalized stacking fault energy curves of different slip systems,it can be obtained that the unstable stacking fault energy of the base surface in the<2(?)(?)0>slip direction is more than three times higher than the unstable stacking fault energy in the<01(?)0>direction of the base plane,and the{0001}<01(?)0>slip system is more likely to be excited at this time.The causes of microscopic deformation mechanism are analyzed from the perspective of energy,which verified the above conclusions.In this paper,a shear-shaped molecular dynamics model of titanium is also simulated,and its behavior is also affected by the loading direction.At a temperature of 300K and a strain rate of 10~8^-1,the plastic deformation of shear in the(01(?)0)[2(?)(?)0]system and the(0001)[2(?)(?)0]system can both be divided into elastic stage,yield stage,process hardening stage and fracture stage,the former has a slightly higher yield stress than the latter.Therefore,it can be concluded that the shear deformation of the[2(?)(?)0]orientation of the base surface is more easily excited than that of the cylinder.