Preparation of TiAl-based alloys by induction melting in graphite crucibles

Čegan, Tomáš; Szurman, Ivo; Kursa, Miroslav; Holešinský, Jan; Vontorová, Jiřina

doi:10.4149/km_2015_2_69

Cited by 11 publications

(7 citation statements)

References 34 publications

(55 reference statements)

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“…Melting crucibles showing the highest thermochemical stability against TiAl melts such as ZrO 2 and Y 2 O 3 are expensive, and CaO is sensitive to the humidity [27][28][29][30]. As was reported by several authors [13,31,32], an increase of carbon content during vacuum induction melting in relatively cheap graphite crucibles can be successfully controlled by processing parameters. Hence, it is of large interest to apply vacuum induction melting in graphite crucibles for processing of TiAl-based matrix composites reinforced with carbide particles.…”

Section: Introductionmentioning

confidence: 84%

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: Introductionmentioning

confidence: 84%

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

Klimová¹,

Lapin²

2020

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“…1c) changes to near γ due to full dissolution of the α 2 phase. In all studied alloys, the partial or full dissolution of the α 2 phase leads to the precipitation of fine secondary carbide particles [13,25]. Figure 2 shows the typical examples of distribution curves of the measured size of the primary carbide particles before compression testing (BC).…”

Section: The Microstructure Of Compression Specimens Before Testingmentioning

confidence: 99%

Effect of carbon on the room temperature compressive behaviour of Ti-44.5Al-8Nb-0.8Mo-xC alloys prepared by vacuum induction melting

Stamborska¹,

Lapin²,

Bajana³

2018

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The effect of carbon content x ranging from 1.4 to 3.6 at.% on the room temperature compressive behaviour of Ti-44.5Al-8Nb-0.8Mo-xC (at.%) alloys prepared by vacuum induction melting has been studied. The microstructural analysis by SEM shows that the increase of the carbon content increases the volume fraction of the reinforcing carbide particles and leads to a change of the matrix microstructure from α2(Ti3Al) + γ(TiAl) + β/B2 to γ type. The carbon content affects the morphology and size of the primary plate-like, regular and irregular shaped Ti2AlC particles. The finite element analysis (FEA) of local equivalent strains and quantitative metallography analysis indicate that the mean size of fragmented carbide particles decreases with increasing local equivalent strain in the compression specimens. The differences in work hardening behaviour of the compression specimens with various content of carbon are related to the initial non-uniform deformation, cracking of primary carbide particles, crack propagation and release of some grains from the free surface during compression testing.

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“…Even though the casting method using refractory containing TiAl-based alloy melt inevitably brings about the problem of foreign element contamination, considering its cheap cost, simple operation, advantages of ensuring melt chemical homogeneity, ability to maintain melt superheat as well as industrial-scale production capacity, which remains an extremely commercially promising approach. For this reason, in the past two decades, various refractories such as oxides (Al2O3, CaO, ZrO2, Y2O3, CaZrO3, BaZrO3) [12][13][14][15][16][17][18], carbides (graphite) [19], nitrides (AlN) [20], silicide (Mullite, SiO2) [17,21] and boride (BN) [20] have been extensively evaluated, and two kinds of refractories, Y2O3 and BaZrO3, are currently used successfully. Our research group has done a lot of work on BaZrO3 series perovskite refractories used in Ti alloys melting, and the results show that BaZrO3 series perovskite refractories have excellent corrosion resistance to Ti alloy melt [15,16,22,23].…”

Section: Introductionmentioning

confidence: 99%

Preparation of Ti-46Al-8Nb Alloy Ingots beyond Laboratory Scale Based on BaZrO3 Refractory Crucible

Duan¹,

Mao²,

Yang³

et al. 2022

Preprint

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The high Nb-containing TiAl-based alloy ingot beyond laboratory scale with a composition of Ti-46Al-8Nb (at. %) was prepared by a vacuum induction melting process based on BaZrO3 refractory. An ingot without macroscopic casting defects (such as pipe shrinkage and center line porosity) was finally obtained, and the chemical composition, solidification path, microstructure and tensile properties of the ingots were investigated. The results show that the deviations of Al and Nb content along a 430 mm long central part of the ingot are approximately \mathrm{\pm}0.39 at. % and \mathrm{\pm}0.14 at. %, and the oxygen content in the ingot can be controlled at around 1000 ppm. During the solidification process, the alloy suffered from peritectic reaction and formed columnar grains with anisotropy. In addition to Al segregation and Nb segregation, β-phase particles associated with γ phase at the triple junction of the colonies were observed. Moreover, the mechanical properties of the ingot in the transverse direction are significantly better than those in the longitudinal direction, with a tensile strength of up to high as 700 MPa and a corresponding fracture elongation of 1.1 %.

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Preparation of TiAl-based alloys by induction melting in graphite crucibles

Cited by 11 publications

References 34 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

Effect of carbon on the room temperature compressive behaviour of Ti-44.5Al-8Nb-0.8Mo-xC alloys prepared by vacuum induction melting

Preparation of Ti-46Al-8Nb Alloy Ingots beyond Laboratory Scale Based on BaZrO3 Refractory Crucible

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