Segregation of Mg at TiB2/Al Interface Mitigating the Zr-poisoning Effect

Interfacial segregation can modify a substrate's heterogeneous-nucleation potency. In Al alloys inoculated with TiB2, 2 , for instance, Zr segregation degrades TiB2's 2 ' s nucleation potency and causes the loss of grain refinement, a phenomenon termed the Zr-poisoning effect. Here we use grain-refining tests to demonstrate that the addition of Mg can revive grain refinement from the Zr-poisoning effect. Using advanced transmission electron microscopy, we identify the segregation of Mg at the TiB2/Al 2 /Al interface, which causes the disappearance of the poisoning Ti2Zr 2 Zr two-dimensional compound (2DC). In its place, atomic layers of a nature close to the Al solid, which we term "Al- like layers", develop, rendering the TiB2 2 potent again to catalyse the nucleation of alpha-Al. Thereby, Mg- segregation-modified TiB2 2 particles are reactivated for heterogeneous nucleation of Al grains. Apart from a mitigation of the Zr-poisoning effect, this work may shed further light on the manipulation of heterogeneous nucleation by atomic engineering of the nucleating substrate.