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Microstructural and Microhardness Properties of In Situ Direct Energy Deposition Fabricated Ti-Al-Si-X(Mo+V) Alloys after Isothermal Annealing Heat Treatments
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Microstructural and Microhardness Properties of In Situ Direct Energy Deposition Fabricated Ti-Al-Si-X(Mo+V) Alloys after Isothermal Annealing Heat Treatments

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Abstract:

Titanium aluminide (Ti-Al) has attracted attentions for applications in aerospace and automotive industries due to their unique properties such as low density, high stiffness and high specific strength at ambient and elevated temperatures. However, the ubiquitous manufacturing of components by conventional processing techniques is hindered by the inherent brittleness of TiAl-based alloys at ambient temperature making it difficult to process this type of alloy, thus, restricting their wider application. Moreover, the direct energy deposition (DED) is amenable to surface modifications and manufacturing of near-net shaped part of difficult-to-process materials. Therefore, this study examines Ti-Al-Si-x(Mo+V) alloys produced from elemental powders via laser in-situ alloying through DED technique using the laser engineered net shaping (LENS) machine. The focus of this investigation was to examine the influence of heat treatment on the alloys at varied Mo+V feed rates after laser in-situ alloying. Isothermal annealing heat treatment, was performed at 1150 °C for 15 min, 30 min, and 60 min, and at 1200 °C, 1300 °C, and 1400 °C for 60 min and furnace cooled (FC), followed by homogenization heat treatment at 950 °C for 6 hours and FC. It was observed that the microstructure revealed relatively large β0-phase precipitates within the lamellae and α2+γ lamellae colony boundaries. It was deduced that the presence of ζ-Ti5Si3 causes an increase in the alloys’ microhardness, which is notable after heat treatment at 1150 °C and 1200 °C, with microstructures of columnar and duplex phases, respectively.

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Periodical:

Key Engineering Materials (Volume 1060)

Pages:

3-22

DOI:

https://doi.org/10.4028/p-Kav0X8

Citation:

Cite this paper

Online since:

July 2026

Authors:

Sadiq Abiola Raji*, Abimbola Patricia Idowu Popoola

Keywords:

Additive Manufacturing, Direct Energy Deposition (DED), Heat Treatment, Laser Engineered Net Shaping (LENS), Laser In-Situ Alloying, Microhardness, Titanium Aluminide (Ti-Al) Alloys, β0- TiAl Phase, ζ-Ti5Si3 Phase

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© 2026 Trans Tech Publications Ltd. All Rights Reserved

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