Influence of Alloy Composition on Hot Deformation Properties of Ti-Al Binary Intermetallics.

Nobuki, Minoru; Tsujimoto, Tokuzou

doi:10.2355/isijinternational.31.931

Cited by 39 publications

(14 citation statements)

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“…Q is the activation energy of the relevant thermally activated process, n is a constant, T the absolute temperature, k the Boltzmann constant, and a ¼ 5 £ 10 23 MPa 21 for the conditions applied here [28]. The evaluation of the experimental data based on Eq.…”

Section: Primary Ingot Break-downmentioning

confidence: 99%

Physical aspects of hot-working gamma-based titanium aluminides

et al. 2004

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Section: Primary Ingot Break-downmentioning

confidence: 99%

Physical aspects of hot-working gamma-based titanium aluminides

et al. 2004

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“…However, the applications of TiAl alloys in large-scale is prevented due to their natural brittleness [5,6]. In order to improve the hot workability of these alloys, many studies have considered the approach of multipass deformation [7][8][9].…”

Section: Introductionmentioning

confidence: 99%

Characteristics of metadynamic recrystallization of a high Nb containing TiAl alloy

et al. 2013

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“…1) In general, thermomechanical processing has been used for an improvement of hot workability, 2) resulting that precisely controlled microstructure showed an excellent superplasticity at elevated temperatures.…”

Section: Introductionmentioning

confidence: 99%

Microstructural Control for Superplasticity Simply by Heat Treatment without Thermomechanical Processing in a Ti-46Al-3.5Cr Alloy.

2000

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Microstructural evolution only by heat treatment has been studied for a Ti-46at%Al-3.5at%Cr alloy, in order to obtain a microstructure which causes superplasticity at high temperatures. By changing the cooling rate from 1 613 K in the a-Ti single-phase region, three kinds of microstructures were identified. Namely, lamellar microstructure appeared by furnace cooling, feathery microstructure took place by air-cooling and massive microstructure prevailed by oil quenching. During subsequent annealing at 1 473 K in the bϩg twophase region, the feathery microstructure turns to fine microdual structure with the equiaxed g grains with 13 mm in grain size and the b precipitates formed along the g grain boundaries. In a tensile test at 1 473 K with a strain rate of 3.2ϫ10 Ϫ4 s Ϫ1, this b/g microdual structure exhibits remarkable superplastic deformation with an elongation of 450 %, which is the same with that obtained by the b/g microdual structure prepared by a thermomechanical processing. On the other hand, the lamellar microstructure and the massive microstructure are not transformed to the b/g microdual structure with the equiaxed g grains, resulting in low elongations of 30 % and 110 % at 1 473 K, respectively. KEY WORDS: titanium aluminide; heat treatment; phase transformation; feathery microstructure; microdual structure; high temperature deformation.1 613 K in the a single-phase region, followed by furnace cooling, air-cooling or oil quenching to obtain the lamellar microstructure, the feathery microstructure or the massive microstructure, respectively. Corresponding to the different cooling methods, the three kinds of specimens are termed as FC, AC and OQ, respectively. After mechanical polishing to remove oxidized surface, the specimens were subsequently annealed at 1 473 K in the bϩg two-phase region for 3.6 ks. The annealed specimens of FC, AC, OQ are called FCA, ACA and OQA, respectively. The tensile specimens with a gauge length of 10 mm and a cross section of 3.5ϫ3.5 mm 2 were prepared from the specimens after annealing. Tensile tests were conducted at 1 473 K with a strain rate of 3.2ϫ10 Ϫ4 s Ϫ1. Microstructural characteristics of as-cooled, annealed and deformed specimens were examined with an optical microscope using polarization and Normarski interference contrast and a scanning electron microscope (SEM). Figure 2 shows optical microstructures of the specimens after solution treatment at 1 613 K for 1.8 ks followed by continuous cooling at various rates. These images in Figs. 2(a)-2(c) and Figs. 2(e)-2(f) were taken from the same area using polarization and Normarski interference contrast microscopy, respectively. As seen in Fig. 2(a) and Fig. 2(d), the sample FC exhibits the lamellar microstructure, which developed with a single orientation in one parent a grain. The lamellar grains corresponding to the parent a grains are extremely large more than one millimeter in size and their grain boundaries exhibit serration. Their thin plates are composed of the a 2 -Ti 3 Al and the g phases. Results and Discu...

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Influence of Alloy Composition on Hot Deformation Properties of Ti-Al Binary Intermetallics.

Cited by 39 publications

References 0 publications

Physical aspects of hot-working gamma-based titanium aluminides

Physical aspects of hot-working gamma-based titanium aluminides

Characteristics of metadynamic recrystallization of a high Nb containing TiAl alloy

Microstructural Control for Superplasticity Simply by Heat Treatment without Thermomechanical Processing in a Ti-46Al-3.5Cr Alloy.

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