Mechanical Properties Of Penta-graphene And High Entropy Alloy:A Molecular Dynamics Study

Penta-graphene（PG）is a graphene allotrope discovered in recent years.Its unique atomic structure,excellent mechanical performance,thermal properties and broad potential applications have attracted extensive attention of carbon materials scholars.In view of the particularity of penta-graphene atomic structure and the scale ofmaterial,conventional experimental research is not only demanding for experimental equipment,but also difficult for the preparation of nano-materials.The emergence of numerical simulation is a powerful complement to traditional theory and experimental methods.Molecular simulation technology is of great significance in revealing and predicting the properties of materials at atomic scale.On the basis of previous studies,the atomic structure model of penta-graphene was constructed and optimized.The mechanical properties of penta-graphene were studied by molecular dynamics simulation in this paper.Firstly,the mechanical properties of penta-graphene,armchair graphene and zigzag graphene were compared.Secondly,the effect of temperature on the tensile properties of penta-graphene was studied.The results show that pentagonal graphene undergoes elastic deformation stage,yield stage,strengthening stage and local deformation and fracture stage under tensile load.With the increase of temperature,the tensile strength of penta-graphene is significantly reduced,and the Young’s modulus is slightly decreased.The failure mechanism at different temperatures is analyzed from the perspective of atomic structure change during tensile failure.The mechanical properties of AlCrFeCuNi high Entropy Alloy（HEA）under axial loading were also studied in this paper.HEA have high strength,high hardness,high wear resistance and corrosion resistance which traditional alloys do not have,and has broad application prospects.Molecular dynamics method was used to simulate the experimental preparation process of high-entropy alloys and establish an atomic model.The mechanical properties of AlCrFeCuNi_1.4.4 HEA at different temperatures and strain rate were studied.The deformation process and the reasons for its high plasticity were analyzed from the point of view of material science.The simulation results show that the AlCrFeCuNi_1.4.4 HEA undergoes elastic deformation,yield and plastic deformation stages under tension and compression loads.Tensile strength increases with the increase of strain rate,and there is strain rate strengthening effect.The elastic modulus,tensile and compression strength and other mechanical properties of AlCrFeCuNi_1.4.4 high-entropy alloy decrease significantly with the increase of temperature.In the yield stage,twins and stacking faults begin to appear.The material changes from FCC phase to HCP phase.The appearance and growth of twins and stacking faults are one of the main reasons for the uneven plastic deformation of the alloy.The effects of Al concentration on the tensile properties of Al_xCrFeCuNi high-entropy alloys were studied by molecular dynamics simulation.The mechanical properties of HEA with different Al concentration at different temperatures were compared.The analysis shows that the Young’s modulus and yield stress of high-entropy alloys decrease linearly with the increase of Al concentration.The HEA have strong temperature effect.The Young’s modulus and yield stress of high-entropy alloys decrease with the increase of temperature,and the decreasing trend is close to linearity.