Using Molecular Dynamics To Simulate The Radiation Damage And Point Defects On Tensile Mechanical Properties Of Single Crystal ?-Zr

In this paper,the dynamic process of displacement cascade of single crystal ?-zirconium at atomic scale was firstly studied by molecular dynamics.The effect of temperature,energy and direction of the Primary Knock-on Atom(PKA)on the radiation damage was investigated.It was found that the increase of temperature would cause a small decline of the number of Frenkel defects.The effect of PKA energy on the radiation damage was the largest and with the increase of PKA energy,the number of Frenkel defects generated by the radiation increased steadily.PKA direction had little influence on the number of Frenkel defects,but it would cause the distribution different.Then uniaxial [0001] tensile tests were carried out on the defect model after irradiation damage,and it was found that the yield strength of single crystal ?-zirconium would be significantly reduced by Frenkel defect pairs generated by irradiation,and the yield strength presented a gradually decreasing trend with the increase of PKA energy.By analyzing the microstructure evolution of tensile deformation process,it was found that irradiation induced defects provide nucleation location for dislocation or dislocation loop,thereby guides the twinning or slip of crystal and leads to the sharp increase of dislocation in crystal,which results in a significant decrease in yield strength relative to single crystal ?-zirconium.Futhermore,three different types of point defects(vacancy,interstitial atoms and Frenkel defect)model were constructed to conduct mechanical tensile simulation.It was found that the yield strength of interstitial atoms decreased the most compared with pure single crystal ?-zirconium,followed by Frenkel defect pairs,and the vacancy was the smallest.Compared with vacancy,interstitial atoms are more likely to aggregate and evolve into defect clusters such as dislocation or dislocation loop during the stretching process.With the increase of defect concentration,the annihilation of interstitial atoms with vacancy slows down the speed of interstitial atoms aggregation to form dislocation loop and other defect clusters.