学術雑誌論文

学術雑誌論文

text

Metals and Materials International. 2023, 30, p. 1227-1241

Microstructure and Crystallographic Texture Evolution of β-Solidifying γ-TiAl Alloy During Single- and Multi-track Exposure via Laser Powder Bed Fusion

Korean Institute of Metals and Materials

英語

text

2023-12-19

https://doi.org/10.1007/s12540-023-01579-4

The version of record of this article, first published in Metals and Materials International, is available online at Publisher’s website: https://doi.org/10.1007/s12540-023-01579-4.

The microstructural evolution and crystallographic texture formation of β-solidifying Ti-44Al-6Nb-1.2Cr alloy were identified under single- and multi-track exposures via laser powder bed fusion (L-PBF) for various process parameters. Under single-track exposure, the microstructure of the melt pool was divided into the band-like α2 phase in the melt pool boundary and β phase in the melt pool center. Numerical and thermodynamic simulations revealed that the underlying mechanism of phase separation was related to the variation in the cooling rate in the melt pool, whereas microsegregation induced a shift in the solidification path. Meanwhile, the crystallographic texture of the α2 phase region was identical to that of the substrate owing to the epitaxial growth of the β phase and subsequent α phase nucleation. In contrast, the β phase exhibited a ± 45° inclined <100> alignment in the melt pool, which was tilted to align along the build direction toward the center of the melt pool corresponding to the simulated thermal gradient direction. Furthermore, the narrow hatch space condition maintained the crystallographic texture to the subsequent scan, forming a continuous band-like α2 phase with a strong selection. However, the crystallographic texture in a wide hatch space condition manifested a random distribution and constituted a fine mixture of the β and α2 phases. For the first time, these results will offer an understanding of an anisotropic microstructure control via the L-PBF process and ensure the tailoring of the mechanical properties in the β-solidifying γ-TiAl-based alloys by approaching hatch spacing control. Graphic Abstract: [Figure not available: see fulltext.]

This article is licensed under a Creative Commons Attribution 4.0 International License.

93543

Microstructure and Crystallographic Texture Evolution of β-Solidifying γ-TiAl Alloy During Single- and Multi-track Exposure via Laser Powder Bed Fusion

Korean Institute of Metals and Materials

英語

2023-12-19

Metals and Materials International

30

1227

1241

https://doi.org/10.1007/s12540-023-01579-4

https://hdl.handle.net/11094/93543