Thermal expansion characteristics of Ti3Al and the effect of additives

Shashikala, H.D.; Suryanarayana, S. V.; Murthy, K. P. N.; Seetala, Naidu V.

doi:10.1016/0022-5088(89)90444-x

Cited by 14 publications

(2 citation statements)

References 5 publications

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“…According to literature reports, the coefficient of thermal expansion for the α 2 phase and B 2 phase at room temperature is reported as 3.26 © 10 ¹5 K ¹1 and 1.45 © 10 ¹5 K ¹1 , respectively. [24][25][26] Notably, the B 2 phase exhibits a more pronounced dependence on temperature, resulting in an increasing disparity in thermal expansion coefficients with rising temperatures. Consequently, this significant mismatch between the α 2 and B 2 phases' coefficients of thermal expansion gives rise to substantial thermal residual stresses near the interface region during laser directed energy deposition processes, ultimately leading to crack formation.…”

Section: Microstructure Analysismentioning

confidence: 99%

Influence of Substrate Preheating on the Formation of Cracks and Microstructure in Ti-48Al-2Cr-2Nb Alloy via Laser Directed Energy Deposition

Cui,

Liu,

Bian

2024

Mater. Trans.

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Due to its exceptional high temperature mechanical properties and low density, TiAl alloy has emerged as a promising structural material for high temperature applications. However, the inherent brittleness and susceptibility to cracking pose challenges during processing. In the additive manufacturing process of TiAl alloy, substrate preheating plays a crucial role in mitigating crack formation. This study focuses on the fabrication of crack-free Ti-48Al-2Cr-2Nb alloy via laser directed energy deposition (LDED), investigating the influence of preheating on sample cracks and microstructure. The results demonstrate that substrate preheating significantly affects the quality of formed samples. Without preheating, numerous cracks are observed in the samples; however, their severity gradually decreases with increasing preheating temperature. Notably, when the substrate was heated to 400°C, no cracks were detected in the samples. Moreover, higher preheating temperature lead to reduced grain length-diameter ratio and partial equiaxed crystal formation along with increased average grain size and α 2 phase proportion while decreasing average orientation difference slightly. The microhardness exhibited a subtle declining tendency. With an increase in the proportion of α 2 phase, the stress generated between different phases is reduced. Additionally, increasing the preheating temperature reduces dislocation density and releases stress, thereby inhibiting crack generation.

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Section: Microstructure Analysismentioning

confidence: 99%

Influence of Substrate Preheating on the Formation of Cracks and Microstructure in Ti-48Al-2Cr-2Nb Alloy via Laser Directed Energy Deposition

Cui,

Liu,

Bian

2024

Mater. Trans.

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show abstract

“…The beads arrangement ratio of the second, third and last six layers were set to Ti:Al ¼ 5:1, 4:2 and 3:3, respectively. expansion (CTE) of pure Ti is 8.6 Â 10 À6 K À1 at room temperature [12] and that of Ti 3 Al is 10.3 Â 10 À6 K À1 [13]. The compositional analysis by EDS against the nominal value of each sample is listed in Table 2.…”

Section: Formation Of Compositionally Graded Samplementioning

confidence: 99%