Molecular Dynamics Simulation Of Plastic Deformation Mechanism Of Aluminum Single Crystal

In this paper,the molecular dynamics simulation and visualization analysis of uniaxial stretching of aluminum were performed based on the core ovito of lammps.In the process of simulation,the initial models with and without nanoholes are established respectively.Different molecular dynamics conditions are applied to the initial models while uniaxial compression and uniaxial tension are carried out.After the simulation,the data of atomic stress,temperature,pressure and coordinates at different times are recorded,and then the compression and tensile processes under different conditions are analyzed and explained in detail by using ovito according to the stress-strain curve and atomic trace diagram.The work and conclusions of this paper are as follows:In the study of the influence of temperature on the single crystal of aluminum,I set up the model of aluminum cell,and then expanded from lammps to the initial model of 80weiz×80a0×10a0 super cell with periodic boundary conditions,which contains about 256000 atoms.The different initial temperature of the model was given to carry out uniaxial tensile and uniaxial compression along the x-axis respectively.The results show that with the increase of temperature,all dislocations provide more energy for the sub dislocations,which further produces more stacking faults.Secondly,because stacking faults are not permanent,higher temperature will also make stacking faults more unstable,leading to large reaction and twinning of stacking faults,thus minimizing the system energy.At a certain temperature and strain,the stacking fault of the compressed aluminum single crystal is larger than that of the stretched aluminum single crystal.In addition,with the increase of temperature,the strain of stacking fault begins to decrease.In the study of the influence of uniaxial tension and compression with nano holes on aluminum single crystal,the simulation is carried out by changing the diameter of nano holes in the model.The results show that dislocations begin to form when the compressive strain is about 0.06,and then rapidly increase to a relatively large and stable level.The beginning of dislocation generation marks the beginning of inelastic deformation.Like the sub dislocation,all dislocations are generated on the surface of nanoholes,so the stacking fault generated by dislocation splitting also appears around the nanoholes first.With the collapse or increase of nanopores,dislocations begin to increase,accumulate and expand to the surrounding area with the strain loading.At the same time,there are other types of dislocations.Dislocations appear preferentially on the upper and lower surfaces of the nanopores,which is the result of stress concentration in the strain loading region.