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The Al-5Ti-0.2C-based grain refiners with different contents of rare earth(RE) were successfully prepared via powder metallurgy and vacuum casting. The microstructural evolution has been studied by X-ray diffraction(XRD), differential scanning calorimetry(DSC), scanning electron microscopy(SEM) and transmission electron microscopy(TEM). The results showed that the RE addition resulted in the formation of Ti Al3/Ti2Al20 RE core-shell structured primary particles, and the size of Ti Al3 core decreased, while the thickness of Ti2Al20 RE increased with increase of RE contents. As compared to Al-5Ti-0.2C grain refiner, the grain refining efficiency was gradually improved with increase of RE contents, which was mainly attributed to the Ti Al3/Ti2Al20 RE core-shell structured primary particles and insoluble Ti C nuclei formed in α-Al matrix. The formation mechanism of core-shell structure was further investigated based on Ginstling-Brounstein model.
The microstructure evolution has been studied by X-ray diffraction (XRD), differential scanning calorimetry (DSC) ), scanning electron microscopy (SEM) and transmission electron microscopy (TEM). The results showed that the addition of the RE in resulted in the formation of Ti Al3 / Ti2Al20 RE core-shell structured primary particles, and the size of Ti Al3 core decreased, while the thickness of Ti2Al20 RE increased with RE contents. As compared to Al-5Ti-0.2C grain refiner, the grain refining efficiency was gradually improved with the increase of RE contents, which was primarily attributed to the Ti Al3 / Ti2Al20 RE core- shell structured primary particles and insoluble Ti C nuclei formed in α-Al matrix. The formation mechanism of core-shell structure was further investigated based on Ginstling-Brounstein model.