Contribution of SiC particles to the formation of the structure of Mg-3 wt.% RE cast composites

A structural analysis of a Mg-3 wt.% rare earths (RE) matrix alloy and composites reinforced with 30 wt.% SiC particles has been performed. The specimens were obtained by gravity casting of the mechanically mixed suspension. The as-cast Mg-3 wt.% RE alloy was characterized by a dendritic microstructure with a very strong segregation of the alloying elements and the formation of the Mg12RE intermetallic phase, located in the interdendritic spaces. Introduction of the SiC particles into the matrix alloy caused the formation of a reaction layer at the interfaces between the components. Transmission electron microscopy analysis allowed the determination of the presence of RE3Si2 precipitates both at the interfaces between the components and in the composite matrix.