Microstructure and formation mechanism of grain-refining particles in Al-Ti-C-RE grain refiners

徐聪¹，肖文龙¹，花田修治³，山县裕⁴，马朝利¹

1. Key Laboratory of Aerospace Advanced Materials and Performance of Ministry of Education, School of Materials Science and Engineering, Beihang University3. Institute for Materials Research, Tohoku University4. Center for Advanced Die Engineering and Technology, Gifu University, 1-1 Yanagido

摘 要：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.

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