<i>In-situ</i> TEM observation of the Nd segregated {101¯2} twin boundary migration mechanism

Interface segregation of solute atoms significantly influences the mechanical properties of magnesium alloys, though the underlying mechanism remains elusive. Here we directly observe the migration dynamics of a Nd segregated {101¯2} twin boundary (TB) via in-situ TEM. The TB exhibits discontinuous, hopping motion with a decreased stress accumulation period. Crucially, most segregated Nd solute atoms do not co-migrate with the advancing TB, consequently inducing high-density stacking faults. This work experimentally clarifies the atomic-scale pinning mechanism of RE segregation on TBs, offering insights into tailoring twinning behavior for optimizing the strength and ductility of magnesium alloys.