Crystal growth for different substrate orientations during laser directed solidification of single crystal superalloys

Article Chemistry, Physical

Investigation on the hot crack sensitivity of a nickel-based single crystal superalloy fabricated by epitaxial laser metal forming

Zhiguo Chen et al.

Summary: In this study, the epitaxial laser metal forming (E-LMF) process was used to deposit a nickel-based single crystal superalloy under different cooling conditions, and its microstructure and formation mechanism were investigated. The results show that almost crack-free epitaxial microstructure is formed under air-cooling, while water-cooling increases the hot crack sensitivity of the deposited alloy. Cracks mainly occur in the overlap zone under water-cooling, while the crystal orientation of the deposited zone is consistent with the substrate under air-cooling.

JOURNAL OF ALLOYS AND COMPOUNDS (2023)

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Article Materials Science, Multidisciplinary

New alloy design approach to inhibiting hot cracking in laser additive manufactured nickel-based superalloys

Yanan Zhao et al.

Summary: In this study, a new approach utilizing segregation engineering and liquid backfilling was introduced to eliminate hot cracking in laser additive manufacturing of alloys. The introduction of zirconium into a nickel-based superalloy formed a continuous interdendritic liquid film, and the decorated Ni11Zr9 segregation phase on cell boundaries effectively eliminated cracks. Moreover, the continuous Ni11Zr9 network layer significantly improved the yield strength of the as-printed samples and exhibited excellent mechanical properties after appropriate heat treatment.

ACTA MATERIALIA (2023)

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Article Optics

Prediction of solidification microstructure of titanium aluminum intermetallic alloy by laser surface remelting

Jiawei Wang et al.

Summary: By controlling the processing parameters in laser additive manufacturing, the mechanical properties of titanium aluminum alloy can be modified. The study developed a numerical model to predict solidification microstructure and investigate the effects of laser processing parameters on dendrite arm spacing. Experimental results show that the model is effective in predicting the solidification microstructure. The scanning velocity plays a dominant role in changes in dendrite arm spacing, while the impact of laser power gradually increases with higher scanning velocity.

OPTICS AND LASER TECHNOLOGY (2022)

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Article Materials Science, Multidisciplinary

Fracture toughness and fatigue crack growth rate studies on rotary friction weldments of nickel-based superalloys

Tom Saju et al.

Summary: This paper investigates the fracture toughness and fatigue crack growth rate of dissimilar metal welded joints made of Inconel 718 and Nimonic 80A. The results show that the crack growth resistance of the welded joints is inferior to the base metals, but improves after post-weld heat treatment.

MATERIALS LETTERS (2022)

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Article Materials Science, Multidisciplinary

A comparable study on stray grain susceptibilities on different crystallographic planes in single crystal superalloys

J. C. Guo et al.

Summary: The substrate orientation significantly affects the formation of stray grains in laser remelted single crystal superalloys, with a greater impact on (011) and (111) planes compared to the (001) plane. The susceptibility to stray grain formation is weakest in the (011) plane and strongest in the (111) plane, attributed to the lower volume fraction of local stray grains on the (011) plane. A laser repair performed in the (011) plane along the [100] direction can most effectively depress stray grain formation, providing insights into avoiding stray grain formation in future laser repairs of single crystal components.

ACTA MATERIALIA (2021)

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Article Chemistry, Physical

Microstructure and stress-rupture property of DD32 nickel-based single crystal superalloy fabricated by additive manufacturing

Shiwei Ci et al.

Summary: Additive manufacturing of crack-free nickel-based single-crystal superalloys using pulsed laser has shown longer stress rupture life compared to conventionally cast alloys. The improvement is attributed to the finer dendritic structure, lower inter-dendritic segregation, and evenly distributed carbides in the additive manufactured samples.

JOURNAL OF ALLOYS AND COMPOUNDS (2021)

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Article Chemistry, Physical

Directional coarsening behavior of primary γ′ phase in Ni3Al-based superalloy during aging heat treatment

Xin He et al.

Summary: The study investigates the directional coarsening behavior of gamma(I)' in polycrystalline Ni3Al-based superalloy under different cooling conditions at 1100 degrees C. It is found that gamma(I)' grows into lamellar and gradually becomes irregular during the directional coarsening process, with driving force mainly depending on the competition of elemental diffusion, lattice misfit distribution, and gamma channel distance.

JOURNAL OF ALLOYS AND COMPOUNDS (2021)

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Article Chemistry, Physical