Novel single crystalline-like non-equiatomic TiZrHfNbTaMo bio-high entropy alloy (BioHEA) developed by laser powder bed fusion

Gokcekaya, Ozkan; Ishimoto, Takuya; Kim, Yong Seong; Matsugaki, Aira; Ozasa, Ryosuke; Weinmann, Markus; Schnitter, Christoph; Stenzel, Melanie; Kim, Hyoung Seop; Miyabayashi, Yoshitsugu; Nakano, Takayoshi

doi:10.1080/21663831.2022.2147406

Cited by 21 publications

(5 citation statements)

References 30 publications

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“…13) The elemental segregation can be successfully suppressed under rapid cooling conditions. 29,30) In addition, XRD and SEM-EBSD analyses were conducted to confirm the constituent phase of the powders (Fig. 5).…”

Section: Resultsmentioning

confidence: 99%

Effect of Cooling Rate on Powder Characteristics and Microstructural Evolution of Gas Atomized β-Solidifying γ-TiAl Alloy Powder

Park,

Ozasa,

Gokcekaya

et al. 2024

Mater. Trans.

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The gas atomization is a production technique of a metallic powder. In this study, the β-solidifying Ti-44Al-6Nb-1.2Cr alloy powder fabricated by gas-atomization was investigated regarding the evolving shape, phase constitution, and chemical distribution as a result of the high solidification rate. The powder showed a spherical shape regardless of its size, indicating no relation of solidification rate to powder shape. However, the small powder (D 50 = 36.0 µm) showed less segregation and was composed of β and α 2 dual phases. Whereas, the large powder (D 50 = 78.7 µm) is relatively high segregation and composed of almost a single α 2 phase because of the difference in the cooling rates. The findings obtained here demonstrated the understanding of phase transformation during the rapid solidification and continuous microstructural evolution process in the β-solidifying alloy.

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Section: Resultsmentioning

confidence: 99%

Effect of Cooling Rate on Powder Characteristics and Microstructural Evolution of Gas Atomized β-Solidifying γ-TiAl Alloy Powder

Park,

Ozasa,

Gokcekaya

et al. 2024

Mater. Trans.

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“…The AM process, characterized by rapid solidification and repeated thermal cycling, can enable unique microstructure control. Additionally, this process affords control over the crystallographic orientation [36,37] and can potentially be used to regulate the α 2 /γ lamellar orientation [38], which can significantly improve the mechanical properties. Overall, this study suggests that preheating and/or subsequent heat treatment at high temperatures during AM can yield precipitation of fine β/γ cell microstructures.…”

Section: Discussionmentioning

confidence: 99%

Microstructure Evolution of Gas-Atomized β-Solidifying γ-TiAl Alloy Powder during Subsequent Heat Treatment

Park,

Gokcekaya,

Ozasa

et al. 2023

Crystals

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To promote the use of γ-TiAl alloys in various domains, such as the aerospace industry, it is pivotal to investigate the unusual phase transformation from rapidly solidified and metastable γ-TiAl toward the equilibrium state. In this study, the microstructure characteristics of gas-atomized β-solidifying Ti-44Al-6Nb-1.2Cr alloy powder, in terms of the effect of rapid solidification on microstructure evolution, were explored in comparison with cast materials. The phase constitution, morphology, and crystallographic orientation between phases were noted to be distinct. Furthermore, subsequent heat treatment was conducted at different temperatures using gas-atomized powder. The transition from the metastable to equilibrium state was observed, wherein firstly, the γ phase precipitated from the retained α2 phase, forming an α2/γ lamellar microstructure. In intensified heat-treatment conditions adequate for cellular reaction, β/γ cells were formed at the grain boundaries of α2/γ lamellar colonies. The findings highlight the overall phase transformation during rapid solidification and continuous microstructural evolution from the nonequilibrium to the equilibrium state. This research can bridge the gap in understanding the effect of the solidification rate on microstructural evolution and contribute to enhanced comprehension of the microstructure in other domains involving rapid solidification, such as the additive manufacturing of γ-TiAl alloys.

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“…PBF-LB/M offers the advantage of fabricating intricate components in near-net shapes [13][14][15][16]. Furthermore, it enables the attainment of distinctive microstructures characterized by high cooling rates (10 5 -10 7 K/s) and steep temperature gradients, facilitating control over crystallographic textures [17][18][19][20][21]. Specifically, texture control, encompassing crystal orientation manipulation, emerges as a pivotal determinant influencing material property, alongside mechanical attributes including strength [22,23], ductility [22,23], Young's modulus [19,24], and other functional characteristics such as corrosion resistance [25], and high-temperature oxidation behavior [26].…”

Section: Introductionmentioning

confidence: 99%

“…Furthermore, it enables the attainment of distinctive microstructures characterized by high cooling rates (10 5 -10 7 K/s) and steep temperature gradients, facilitating control over crystallographic textures [17][18][19][20][21]. Specifically, texture control, encompassing crystal orientation manipulation, emerges as a pivotal determinant influencing material property, alongside mechanical attributes including strength [22,23], ductility [22,23], Young's modulus [19,24], and other functional characteristics such as corrosion resistance [25], and high-temperature oxidation behavior [26]. Consequently, the manipulation of crystallographic texture emerges as a pivotal factor directly influencing material properties, prompting an expansion of research endeavors focused on crystallographic texture control via PBF-LB/M.…”

Section: Introductionmentioning

confidence: 99%

Effect of Laser Scan Speed on the Defects and Texture Development of Pure Chromium Metal Fabricated by Powder Bed Fusion-Laser Beam

Kim,

Gokcekaya,

Matsugaki

et al. 2024

Preprint

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Chromium (Cr) metal has garnered significant attention in alloy systems owing to its exceptional properties, such as high melting point, low density, and superior oxidation and corrosion resistance. However, its processing capabilities are hindered by the high Ductile-Brittle Transition Temperature (DBTT). Recently, powder bed fusion-laser beam for metals (PBF-LB/M) has emerged as a promising technique, offering the fabrication of net shapes and precise control over crystallographic texture. Nevertheless, research investigating the mechanism underlying crystallographic texture development in pure Cr via PBF-LB/M still needs to be conducted. This study explores the impact of scan speed on relative density and crystallographic texture. At the optimal scan speed, an increase in grain size attributed to epitaxial growth was observed, resulting in the formation of cubic texture. Consequently, a reduction in High Angle Grain Boundaries (HAGB) was achieved, suppressing defects such as cracks and enhancing relative density up to 98.1%. Furthermore, with increasing densification, Vickers hardness also exhibited a corresponding increase. These findings underscore the efficacy of PBF-LB/M for processing metals with high DBTT properties.

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Novel single crystalline-like non-equiatomic TiZrHfNbTaMo bio-high entropy alloy (BioHEA) developed by laser powder bed fusion

Cited by 21 publications

References 30 publications

Effect of Cooling Rate on Powder Characteristics and Microstructural Evolution of Gas Atomized β-Solidifying γ-TiAl Alloy Powder

Effect of Cooling Rate on Powder Characteristics and Microstructural Evolution of Gas Atomized β-Solidifying γ-TiAl Alloy Powder

Microstructure Evolution of Gas-Atomized β-Solidifying γ-TiAl Alloy Powder during Subsequent Heat Treatment

Effect of Laser Scan Speed on the Defects and Texture Development of Pure Chromium Metal Fabricated by Powder Bed Fusion-Laser Beam

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