Stability of vacancies in β-type Ti-15Mo-5Zr-3Al alloy fabricated via laser powder bed fusion

Masataka Mizuno; Kazuki Sugita; Kousuke Do; Takuya Ishimoto; Takayoshi Nakano; Hideki Araki

Additive Manufacturing Letters (Dec 2023)

Stability of vacancies in β-type Ti-15Mo-5Zr-3Al alloy fabricated via laser powder bed fusion

Masataka Mizuno,
Kazuki Sugita,
Kousuke Do,
Takuya Ishimoto,
Takayoshi Nakano,
Hideki Araki

Affiliations

Masataka Mizuno: Division of Materials and Manufacturing Science, Graduate School of Engineering, Osaka University, 2-1 Yamadaoka, Suita, Osaka 565-0871, Japan; Corresponding author.
Kazuki Sugita: Division of Materials and Manufacturing Science, Graduate School of Engineering, Osaka University, 2-1 Yamadaoka, Suita, Osaka 565-0871, Japan
Kousuke Do: Division of Materials and Manufacturing Science, Graduate School of Engineering, Osaka University, 2-1 Yamadaoka, Suita, Osaka 565-0871, Japan
Takuya Ishimoto: Division of Materials and Manufacturing Science, Graduate School of Engineering, Osaka University, 2-1 Yamadaoka, Suita, Osaka 565-0871, Japan; Anisotropic Design and Additive Manufacturing Research Center, Osaka University, 2-1, Yamadaoka, Suita, Osaka 565-0871, Japan; Aluminium Research Center, University of Toyama, 3190, Gofuku, Toyama 930-8555, Japan
Takayoshi Nakano: Division of Materials and Manufacturing Science, Graduate School of Engineering, Osaka University, 2-1 Yamadaoka, Suita, Osaka 565-0871, Japan; Anisotropic Design and Additive Manufacturing Research Center, Osaka University, 2-1, Yamadaoka, Suita, Osaka 565-0871, Japan
Hideki Araki: Division of Materials and Manufacturing Science, Graduate School of Engineering, Osaka University, 2-1 Yamadaoka, Suita, Osaka 565-0871, Japan

Journal volume & issue: Vol. 7
p. 100162

Abstract

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The structural instability in the β-type titanium alloys could affect the stability of vacancies. The stability of vacancies in a β-type Ti-15Mo-5Zr-3Al alloy, fabricated via laser powder bed fusion (LPBF), was investigated using positron annihilation spectroscopy and first-principles calculations. The observed positron lifetimes were close to the experimental and calculated bulk lifetime of Ti-15Mo-5Zr-3Al, which indicates that vacancies were not detected in Ti-15Mo-5Zr-3Al by positron lifetime measurements. Therefore, for the first time, it has been confirmed that quenched-in vacancies are not introduced in the LPBF-manufactured β-type Ti-15Mo-5Zr-3Al despite the fast cooling rate in LPBF process. This feature is preferable for the structural stability in biomedical and industrial applications. The calculated atomic displacement from the ideal bcc lattice positions decreased in β-type Ti-Mo alloys with increasing Mo concentration, indicating that the bcc structure was stabilized by the added Mo. The calculated vacancy formation energies of Ti atoms in β-type Ti-14.5Mo and Ti-27.0Mo alloys exhibited an increasing trend with an increasing number of neighboring Mo atoms. Mo atoms also increased the migration energies of the neighboring paths of vacancies. The calculated results for Ti-15Mo-5Zr-3Al suggest that, while the bcc structure was stabilized by the Mo atoms in Ti-15Mo-5Zr-3Al, the migration and formation energies were still low enough for the diffusion of vacancies.

Published in Additive Manufacturing Letters

ISSN: 2772-3690 (Online)
Publisher: Elsevier
Country of publisher: Netherlands
LCC subjects: Technology: Technology (General): Industrial engineering. Management engineering
Website: https://www.journals.elsevier.com/additive-manufacturing-letters/

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