Segregation and clustering of solutes at grain boundaries in Mg-rare earth solid solutions

The present study validates the previously reported investigations about segregation of rare-earth (RE) elements at grain boundaries in Mg-RE alloys and ultimately provides a direct visualization of the distribution of the solute atoms in the structure of a Mg-Gd alloy. It is demonstrated that Gd forms a solid solution within the Mg matrix in addition to substantial segregation at high-angle grain boundaries in the form of 1-2 nm clusters, with a postulated face-centered cubic Gd structure. The results suggest significant implications for the texture development during alloy processing and recrystallization, and thus for the mechanical behavior and properties of Mg-RE alloys.