Microstructure and morphology of Si crystals grown in pure Si and Al-Si melts

L V Toropova; D V Alexandrov; M Rettenmayr; D Liu

doi:10.1088/1361-648X/ac3792

Microstructure and morphology of Si crystals grown in pure Si and Al-Si melts

J Phys Condens Matter. 2022 Jan 10;34(9). doi: 10.1088/1361-648X/ac3792.

Authors

L V Toropova^{1

2}, D V Alexandrov¹, M Rettenmayr², D Liu²

Affiliations

¹ Laboratory of Multi-Scale Mathematical Modeling, Department of Theoretical and Mathematical Physics, Ural Federal University, Ekaterinburg, 620000, Russia.
² Otto-Schott-Institut für Materialforschung, Friedrich-Schiller-Universität-Jena, 07743 Jena, Germany.

PMID: 34749346
DOI: 10.1088/1361-648X/ac3792

Abstract

Microstructure of Al-40 wt%Si samples solidified in electromagnetic levitation furnace is studied at high melt undercooling. Primary Si with feathery and dendritic structures is observed. As this takes place, single Si crystals either contain secondary dendrite arms or represent faceted structures. Our experiments show that at a certain undercooling, there exists the microstructural transition zone of faceted to non-faceted growth. Also, we analyze the shape of dendritic crystals solidifying from liquid Si as well as from hypereutectic Al-Si melts at high growth undercoolings. The shapes of dendrite tips grown at undercoolings >100 K along the surface of levitated Al-40 wt%Si droplets are compared with pure Si dendrite tips from the literature. The dendrite tips are digitized and superimposed with theoretical shape function recently derived by stitching the Ivantsov and Brener solutions. We show that experimental and theoretical dendrite tips are in good agreement for Si and Al-Si samples.

Keywords: dendrite; dendrite tip; interface shape; phase transformation; silicon.