  Solute segregation at twin boundaries in Mg has been widely investigated, yet
this phenomenon has not been studied at the equally important basal-prismatic
interfaces. To fill this critical gap, this work investigates the segregation
behavior of Y at basal-prismatic interfaces with various structures using
atomistic simulations. The calculated interfacial energies show that short
coherent interfaces and long semi-coherent interfaces containing disconnections
and dislocations are more energetically stable than disordered interfaces,
which is supported by our experimental observations. The segregation energy of
Y at these lowest energy basal-prismatic interfaces shows a clear correlation
with the atomic hydrostatic stress, highlighting the importance of local
compressive stresses for segregation. In addition, sites around dislocations at
the semi-coherent basal-prismatic interfaces demonstrate lower segregation
energy, indicating that local defects such as interfacial dislocations can
further enhance the segregation. In its entirety, this study indicates that the
segregation of solutes can be affected by a number of different aspects of the
local structure at complex interfaces in Mg alloys.
