Microstructure and mechanical properties of additively manufactured γ-TiAl with dual microstructure

Knörlein J, Franke MM, Schloffer M, Berger T, Körner C (2023)

Publication Type: Journal article

Publication year: 2023

Journal

Intermetallics Elsevier

Book Volume: 161

Article Number: 107978

DOI: 10.1016/j.intermet.2023.107978

Abstract

The latest research on electron beam powder bed fusion (PBF-EB), additive manufacturing (AM) process, reveals the possibility of establishing a dual microstructure and differing mechanical properties inside a complex-shaped component made of titanium aluminides (TiAl). The functionally graded material (FGM) parts are processed with two different, well-adjusted AM process parameter sets leading to a significant change in localized aluminum (Al) loss via evaporation during PBF-EB. By heat treatment, the as-built microstructure, containing two different levels of Al, is transformed into customized microstructures: fully lamellar (FL) and nearly lamellar (NL + γ). This study aims to determine the microstructural and mechanical characteristics of PBF-EB processed 4th generation TiAl alloy TNM. Tensile and creep tests are performed for single (FL or NL + γ) and dual microstructure specimens with two orientations. The element distribution of aluminum is determined, the microstructures are characterized, and the fracture-inducing defects are identified. The presented new FGM processing route is a groundbreaking benefit from the PBF-EB process and is necessary for superior mechanical performance. The stress-strain and the creep properties of the dual microstructure specimens are situated between the single microstructure specimens. The mechanical characterization shows that the interface between FL and NL + γ does not cause any weakening of the specimens. The failure always takes place in the weaker microstructure (tensile: FL; creep: NL + γ). For the first time, AM components such as TiAl turbine blades can consist of creep-resistant airfoil sections and high-strength root sections taking advantage of new microstructural FGM design possibilities.

Authors with CRIS profile

Timo Berger Lehrstuhl für Werkstoffwissenschaften (Werkstoffkunde und Technologie der Metalle) (WTM) Carolin Körner Lehrstuhl für Werkstoffwissenschaften (Werkstoffkunde und Technologie der Metalle) (WTM)

Involved external institutions

Neue Materialien Fürth GmbH DE Germany (DE) MTU Aero Engines AG DE Germany (DE)

How to cite

APA:

Knörlein, J., Franke, M.M., Schloffer, M., Berger, T., & Körner, C. (2023). Microstructure and mechanical properties of additively manufactured γ-TiAl with dual microstructure. Intermetallics, 161. https://doi.org/10.1016/j.intermet.2023.107978

MLA:

Knörlein, Julia, et al. "Microstructure and mechanical properties of additively manufactured γ-TiAl with dual microstructure." Intermetallics 161 (2023).

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