|About this Abstract
||2019 TMS Annual Meeting & Exhibition
||Solidification Processing of Light Metals and Alloys: An MPMD Symposium in Honor of David StJohn
||Compositional Templating for Heterogeneous Nucleation of Intermetallic Compounds
||Zhongping Que, Zhongyun Fan, Yun Wang
|On-Site Speaker (Planned)
Effective refinement of intermetallic compounds (IMCs) is currently limited by our poor understanding of their heterogeneous nucleation. In this contribution, we present our latest advance in the understanding of heterogeneous nucleation of Fe-containing IMCs in Al-alloys. First we demonstrate that heterogeneous nucleation of IMCs is difficult and requires large nucleation undercooling. Our DSC measurements show that the nucleation undercooling required for IMCs is in the order of tens of Kelvin, and that the undercooling increases with increasing complexity of the stoichiometry of the IMCs. This is because nucleation of IMCs needs to create not only the correct crystal structure but also the correct elemental compositions. We then present our new approach to enhancing heterogeneous nucleation of IMCs by both structural templating and compositional templating. We show that chemical segregation of selected elements at the liquid/TiB2 interface can lead to significant reduction of nucleation undercooling and refinement of IMCs in Al-alloys.