Structure and properties of titanium-aluminum alloys doped with niobium and tantalum

Bondar, A. А.; Witusiewicz, V.T.; Hecht, U.; Remez, М. V.; Voblikov, V. M.; Tsyganenko, N.I.; Yevich, Ya. I.; Podrezov, Yu. N.; Velikanova, Т. Ya.

doi:10.1007/s11106-011-9345-6

Cited by 12 publications

(5 citation statements)

References 71 publications

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“…Since phase diagrams describing phase transformations in the studied composites with chemical composition close to 8 at.% Nb, 1 at.% Mo, and 3.6 at.% C are not available, the solidification path and phase equilibria can be estimated based on phase diagrams reported for Nb-, Nb-Mo-, and C-doped TiAl-based alloys [38][39][40][41][42]. According to the ternary Ti-Al-C-phase diagrams [42], the cubic TiC 1−x -phase is formed as a primary solidification phase in the melt at high temperatures.…”

Section: Discussionmentioning

confidence: 99%

Effect of Al content on microstructure of Ti-Al-Nb-C-Mo composites reinforced with carbide particles

Klimová¹,

Lapin²

2020

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The effect of Al content on the microstructure of Ti-xAl-8Nb-3.6C-0.8Mo (at.%) composites reinforced with carbide particles, where x = 38, 42, 45, and 47 at.%, was studied. The composites prepared by vacuum induction melting in graphite crucibles followed by centrifugal casting into graphite moulds were studied in the as-cast and heat-treated state. The intermetallic matrices of the as-cast composites consisting of α2(Ti3Al)-, γ(TiAl)-, and β/B2(Ti)-phases are reinforced with uniformly distributed carbide particles composed of (Ti,Nb)2AlC-phase and small amount of (Ti,Nb)C-phase preserved in the cores of some coarse irregular shaped carbides. The increasing Al content leads to a decrease in the volume fraction of β/B2-phase and an increase in the volume fraction of the lamellar α2 + γ and single γ-phase regions in the as-cast composites. The increasing Al content increases shape factor and decreases the mean size of the primary carbide particles. In the heat-treated composites, the intermetallic matrices change from multiphase composed of lamellar α2 + γ grains with β/B2-and γ-phase regions formed along the lamellar grain boundaries, through nearly lamellar to single γ-phase with increasing Al content. The (Ti,Nb)C regions in the core of some carbide particles transform to (Ti,Nb)2AlC-phase during the heat-treatment. The Vickers hardness and matrix microhardness decrease with the increasing Al content in both the as-cast and heat-treated composites.

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Section: Discussionmentioning

confidence: 99%

Effect of Al content on microstructure of Ti-Al-Nb-C-Mo composites reinforced with carbide particles

Klimová¹,

Lapin²

2020

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“…This processed microstructure can vary sensitively by the post-HT. The solidification route of Ti-48Al-2Nb-2Cr (at%) during L-PBF follows the decomposition path of α→α + γ→α 2 + γ [ 19 ]. However, it has been observed that the final microstructure was dominated by α 2 phase, while the γ phase scarcely existed [ 11 ].…”

Section: Introductionmentioning

confidence: 99%

Influence of Combined Heat Treatment and Hot Isostatic Pressure (HT-HIP) on Titanium Aluminide Processed by L-PBF

Soliman

Pineault²,

Elbestawi

2023

Materials

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Postprocessing is essential for improving titanium aluminide (TiAl) microstructure and part quality after using the laser powder bed fusion (L-PBF) method. It has been reported that Ti-48Al-2Cr-2Nb (%at) processed by L-PBF has internal defects and low fracture toughness. Microstructure control by heat treatment (HT) showed a significant improvement in the ductility of the material. Alternatively, hot isostatic pressing (HIPing) could be applied to reduce the residual stresses and internal defects formed during the L-PBF. Combining the benefits of these two subsequent processes into a single predetermined process is appealing for Ti-48Al-2Cr-2Nb (%at) to minimize cost. This work presents a novel strategy to postprocess L-PBF TiAl by applying combined heat treatment and hot isostatic pressing in one process, namely HT-HIP. The process includes three cycles with different conditions (i.e., temperature, time, and pressure). These conditions were determined to achieve improved part quality and microstructure. The results show that the tensile residual stresses decreased from a peak of 249 MPa in the as-built sample to compressive stresses that peaked at −90 MPa after the HT-HIP process. The number and size of internal defects could be greatly reduced. The defects were transformed into a regular spherical shape, which is good in terms of fatigue strength. Additionally, a duplex microstructure with lamellar α2/γ colonies could be introduced for better ductility. Different levels of duplex microstructure could be achieved along with the process cycles. The grain structure using EBSD analysis showed refined equiaxed grains, which demonstrate better strength after the HT-HIP process. Twinning boundaries were also observed in the HT-HIP sample. The grain orientation tendency to the build direction significantly reduced after the HT-HIP process. The nanoindentation test was applied to evaluate the nanohardness of the as-built and HT-HIP samples. It could be demonstrated that the nanohardness is dependent on the formed phases and lamellar density inside the grains. The mean hardness value was 8.19 GPa for the as-built sample, while it was 5.48 GPa for the HT-HIP sample.

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“…Some authors conducted chemical and mechanical analyses on several Al-Ti IMC to check their strength and ductility [2]. Others proposed diffusion welding of Ti and Al multi-laminated materials [3].…”

Section: Introductionmentioning

confidence: 99%

Off-Set and Focus Effects on Grade 5 Titanium to 6061 Aluminum Alloy Fiber Laser Weld

et al. 2018

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Joining dissimilar metal alloys together has become a major issue in the welding industry since the rapid development of innovative and performing multi-materials products. In case, titanium and Aluminum alloys can be laser-welded using a placement of the laser beam aside the weld centerline, which is called off-set. The fused zone is deep and narrow and the reaction between titanium and Aluminum is limited to a thin interlayer, which improves mechanical properties. In this paper, the effect of focus and off-set distance of the laser beam on the weldability of grade 5 titanium to 6061 Aluminum alloy dissimilar butt weld are presented. The interlayer thickness was correlated to the process parameters and tensile behavior of the weld. The map of deformation showed different deformations of the two weld sides. The data coming from the metallurgical and mechanical characterization of the weld were analyzed to figure out the best off-set and focus combination in the range studied.

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Structure and properties of titanium-aluminum alloys doped with niobium and tantalum

Cited by 12 publications

References 71 publications

Effect of Al content on microstructure of Ti-Al-Nb-C-Mo composites reinforced with carbide particles

Effect of Al content on microstructure of Ti-Al-Nb-C-Mo composites reinforced with carbide particles

Influence of Combined Heat Treatment and Hot Isostatic Pressure (HT-HIP) on Titanium Aluminide Processed by L-PBF

Off-Set and Focus Effects on Grade 5 Titanium to 6061 Aluminum Alloy Fiber Laser Weld

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