Phase stability and microstructural evolution of Ti2AlNb alloys-a review

Goyal, Kushagra; Sardana, Neha

doi:10.1016/j.matpr.2020.10.925

Cited by 23 publications

(16 citation statements)

References 61 publications

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“…As shown in several publications, the volume fraction and size of O-phase precipitates significantly depend on the processing temperature and/or heat-treatment conditions [ 20 ]. A lower O-phase volume fraction corresponds to higher annealing temperatures in the case of Ti 2 AlNb-based alloys [ 21 ]. This suggests that the top area of the specimen was processed at lower temperatures closer to the single O-phase region during the SLM build compared with the bottom area.…”

Section: Resultsmentioning

confidence: 99%

“…As the result of B2 → O transformation and coarsening of O-phase precipitates during the HIP, the microhardness of the alloy decreased to 360 ± 10 HV HV0.5 compared with the as-fabricated condition. The HIPed alloy also exhibited lower microhardness compared with the annealed condition since the HIP temperature was higher and resulted in a coarser microstructure and higher volume fraction of the B2-phase, which has lower hardness compared with the O-phase [21]. The manufactured dog-bone tensile samples were machined and tested in as-fabricated and HIPed conditions.…”

Section: Effect Of Heat Treatment On Microstructure and Microhardness Of The Orthorhombic Alloy With A Graded Microstructurementioning

confidence: 99%

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Mitigating Inhomogeneity and Tailoring the Microstructure of Selective Laser Melted Titanium Orthorhombic Alloy by Heat Treatment, Hot Isostatic Pressing, and Multiple Laser Exposures

et al. 2021

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Titanium orthorhombic alloys based on intermetallic Ti2AlNb-phase are attractive materials for lightweight high-temperature applications. However, conventional manufacturing of Ti2AlNb-based alloys is costly and labor-consuming. Additive Manufacturing is an attractive way of producing parts from Ti2AlNb-based alloys. High-temperature substrate preheating during Selective Laser Melting is required to obtain crack-free intermetallic alloys. Due to the nature of substrate preheating, the temperature profile along the build height might be uneven leading to inhomogeneous microstructure and defects. The microstructural homogeneity of the alloy along the build direction was evaluated. The feasibility of mitigating the microstructural inhomogeneity was investigated by fabricating Ti2AlNb-alloy samples with graded microstructure and subjecting them to annealing. Hot isostatic pressing allowed us to achieve a homogeneous microstructure, eliminate residual micro defects, and improve mechanical properties with tensile strength reaching 1027 MPa and 860 MPa at room temperature and 650 °C, correspondingly. Annealing of the microstructurally graded alloy at 1050 °C allowed us to obtain a homogeneous B2 + O microstructure with a uniform microhardness distribution. The results of the study showed that the microstructural inhomogeneity of the titanium orthorhombic alloy obtained by SLM can be mitigated by annealing or hot isostatic pressing. Additionally, it was shown that by applying multiple-laser exposure for processing each layer it is possible to locally tailor the phase volume and morphology and achieve microstructure and properties similar to the Ti2AlNb-alloy obtained at higher preheating temperatures.

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Section: Resultsmentioning

confidence: 99%

Section: Effect Of Heat Treatment On Microstructure and Microhardness Of The Orthorhombic Alloy With A Graded Microstructurementioning

confidence: 99%

Mitigating Inhomogeneity and Tailoring the Microstructure of Selective Laser Melted Titanium Orthorhombic Alloy by Heat Treatment, Hot Isostatic Pressing, and Multiple Laser Exposures

et al. 2021

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“… Crystal structures of ( a ) B2, ( b ) α 2 and ( c ) O phase with Wyckoff positions and occupancies. Reproduced with permission from Elsevier [ 25 ]. …”

Section: General Characteristics Of Alloys Based On Ti 2 ...mentioning

confidence: 99%

“…The mechanisms and stages of phase transformations (β(B 2 )-O, α 2 -O, β(B2)-α 2 and β(B 2 ) + α 2 -O in O-phase alloys at constant temperature (during aging or holding after quenching at annealing temperatures) are addressed in quite a few studies and their detailed analysis is given in reviews [ 25 , 27 , 28 , 29 ]; therefore, we shall not dwell on this topic in our review.…”

Section: General Characteristics Of Alloys Based On Ti 2 ...mentioning

confidence: 99%

A Review—Additive Manufacturing of Intermetallic Alloys Based on Orthorhombic Titanium Aluminide Ti2AlNb

et al. 2023

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Titanium alloys based on orthorhombic titanium aluminide Ti2AlNb are promising refractory materials for aircraft engine parts in the operating temperature range from 600–700 °C. Parts made of Ti2AlNb-based alloys by traditional technologies, such as casting and metal forming, have not yet found wide application due to the sensitivity of processability and mechanical properties in chemical composition and microstructure compared with commercial solid-solution-based titanium alloys. In the last three decades, metal additive manufacturing (MAM) has attracted the attention of scientists and engineers for the production of intermetallic alloys based on Ti2AlNb. This review summarizes the recent achievements in the production of O-phase-based Ti alloys using MAM, including the analysis of the feedstock materials, technological processes, machines, microstructure, phase composition and mechanical properties. Powder bed fusion (PBF) and direct energy deposition (DED) are the most widely employed MAM processes to produce O-phase alloys. MAM provides fully dense, fine-grained material with a superior combination of mechanical properties at room temperature. Further research on MAM for the production of critical parts made of Ti2AlNb-based alloys can be focused on a detailed study of the influence of post-processing and chemical composition on the formation of the structure and mechanical properties, including cyclic loading, fracture toughness, and creep resistance.

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“…Titanium Ti 2 AlNb-based intermetallic alloys exhibit high specific strength, creep resistance, serving temperatures of up to 650–750 °C, and can potentially replace nickel-based alloys or steels, which have significantly higher density [ 9 , 10 , 11 ]. However, a major problem of titanium intermetallic alloys consists in low plasticity at room temperature and poor fracture toughness [ 12 ].…”

Section: Introductionmentioning

confidence: 99%

Interface Characterization of Bimetallic Ti-6Al-4V/Ti2AlNb Structures Prepared by Selective Laser Melting

2022

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Additive Manufacturing (AM) of multimaterial components is a promising way of fabricating parts with improved functional properties. It allows for the combination of materials with different properties into a single component. The Ti2AlNb-based intermetallic alloy provides high temperature strength, while the Ti-6Al-4V (Ti64) alloy has good fracture toughness, ductility, and a relatively low cost. A combination of these alloys into a single component can be used to produce advanced multimaterial parts. In this work, Ti2AlNb/Ti-6Al-4V bimetallic structures were fabricated from pre-alloyed powders using the Selective Laser Melting (SLM) process. The effects of high-temperature substrate preheating, post-processing by annealing, and hot isostatic pressing on defect formation, the microstructural evolution of the interface area, and the mechanical properties of the bimetallic samples were investigated. High-temperature substrate preheating during the SLM process was necessary to prevent reheat cracking of the Ti2AlNb part, while annealing and hot isostatic pressing post-processing improved the chemical and microstructural homogeneity of the transition zone and enhanced the tensile properties of the bimetallic structure.

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Phase stability and microstructural evolution of Ti2AlNb alloys-a review

Cited by 23 publications

References 61 publications

Mitigating Inhomogeneity and Tailoring the Microstructure of Selective Laser Melted Titanium Orthorhombic Alloy by Heat Treatment, Hot Isostatic Pressing, and Multiple Laser Exposures

Mitigating Inhomogeneity and Tailoring the Microstructure of Selective Laser Melted Titanium Orthorhombic Alloy by Heat Treatment, Hot Isostatic Pressing, and Multiple Laser Exposures

A Review—Additive Manufacturing of Intermetallic Alloys Based on Orthorhombic Titanium Aluminide Ti2AlNb

Interface Characterization of Bimetallic Ti-6Al-4V/Ti2AlNb Structures Prepared by Selective Laser Melting

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