Abstract：The effect of low energy ion irradiation on metallic glasses（MGs） has been suggested to be described in terms of “vacancy-like” defects，which we call “quasi-vacancy”．Using molecular dynamics simulations，we investigate the plastic deformation behavior of Cu50Zr50 MGs with quasi-vacancies introduced．The effects of volume fraction and distribution area of quasi-vacancies on toughening of MGs were discussed．With quasi-vacancies introduced，the deformation behavior of MGs under different cyclic loads was also analyzed．Our results reveals that the introduction of quasi-vacancies can effectively enhance the ductility of MGs．As the volume fraction of quasi-vacancy increases，the deformation mode of MGs has noticeably changed from localized shear banding to homogeneously plastic deformation．The critical volume fraction of quasi-vacancy for the ductile-brittle transition of MGs is suggested to be about 0．5％．Besides，the more uniform quasi-vacancies are distributed，the better ductility of MGs will be enhanced．The enhanced ductility of MGs by introducing quasi-vacancies can be well maintained under different cyclic loads．When the strain reaches 30％ after several cycles of tension-tension or tension-compression loadings，the ductilie response of MGs remains unchanged．For general metals and alloys，the vacancies introduced by irradiation and the cavities，precipitates，dislocation loops or stacking fault tetrahedrons formed by further evolution usually make the materials brittle．However，for MGs，the vacancy introduced by irradiation is hard to diffuse and further evolve，but may increase the ductility of the material．
2020, Vol. 41 
