Annealing Behavior of Vacancy-Type Defects in Mg-Zn-Y Alloy with LPSO Structure Introduced by Electron-irradiation at Liquid Nitrogen Temperature

Mg alloys containing transition-metal (TM) and rare-earth (RE) elements (Mg-TM-RE) have received a considerable amount of attention in recent years as a new-class of light-weight structural material that exhibits high strength and high ductility, simultaneously. A long-period stacking-ordered (LPSO) structure which is long period stacking variants of hcp-Mg by introducing the TM/RE enriched layers synchronized with stacking faults periodically have been believed to play a critical role in endowing such attractive mechanical properties and high ductility with the Mg-TM-RE alloys. In order to understand the detailed mechanisms for the formation, it is important to investigate the behavior of vacancy-type defects in the material with LPSO structure. Positron annihilation spectroscopy is well known to detect vacancy-type defects in materials. In this work we have investigated annealing behavior of defects introduced by electron-irradiation at liquid nitrogen temperature.