Room Temperature Deformation-induced Solute Segregation and its Impact on Twin Boundary Mobility in a Mg-Y Alloy

Mechanical behavior of alloys is influenced by segregation of solute atoms, which affects deformation mechanisms, such as slip and twinning. In this study, we report on an atomic-scale investigation into room temperature, deformation-induced solute segregation in a Mg-Y alloy. High concentrations of Y were observed at the dislocation cores. In addition, we found that {101¯2} twins were bounded by coherent twin boundaries and basal-prismatic facets, which contained periodic segregation of Y-rich columns and nano-sized Y-rich clusters, respectively. The observed segregation arrangement was energetically attributed to the fact that it minimizes the overall lattice distortion and is kinetically assisted by the dynamic interaction between solute atoms and crystallographic defects and the slip-twin interaction during plastic deformation. Moreover, segregated Y atoms exert a pinning effect and lead to anisotropy on the mobility of twin boundaries. This finding offers a potentially new alloy design path to control the mechanical response of Mg alloys.