Publications
Laser powder bed fusion of titanium aluminides: an investigation on site-specific microstructure evolution mechanism
X. Zhang, B. Mao, L. Mushongera, J. Kundin, Y. Liao.
Materials and Design, 201, 109501, (2021)
Abstract
Metal additive manufacturing (AM) improves the design flexibility of titanium aluminides (TiAl-based alloys) as
a new class of high-temperature alloys towards widespread applications. In this work, the underlying mecha-
nisms responsible for the site-specific thermal history and grain evolution during laser powder bed fusion
(LPBF) of TiAl-based alloys are investigated through an integrated computational and experimental effort. In spe-
cific, a multiphysics modeling framework integrating a finite element thermal model with a highly efficient
phase-field method is developed to simulate the solidification microstructure at different locations within the
melt pool during LPBF processing. The investigation of process-microstructure relationship is accomplished
using a Ti-45Al (at.%) alloy for a binary approximation, with a focus on site-specific primary dendrite arm spacing
(PDAS) and non-equilibrium microsegregation. The microstructural sensitivity to spatial variations, individual
processing parameters, and misorientation angle between the preferred crystalline orientation and the temper-
ature gradient direction are studied to thoroughly understand the rapid solidification during LPBF. LPBF experi-
ments are carried out to validate the modeling results in terms of melt pool dimensions and site-specific PDAS
across the melt pool. The knowledge gained in this work will benefit the development of AM processing routine
for fabrication of high-performance TiAl-based alloys towards extensive applications.
Keyword(s): Laser powder bed fusion; titanium aluminides; phase-field modeling; cellular structure
DOI: 10.1016/j.matdes.2021.109501
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