Microstructure and high temperature mechanical properties of powder metallurgical Ti-45Al-7Nb-0.3W alloy sheets

Li, Huizhong; Yao, Qi; Liang, Xiaopeng; Zhu, Zexiao; Lv, Feng; Liu, Yong; Yang, Yi

doi:10.1016/j.matdes.2016.05.113

Cited by 29 publications

(6 citation statements)

References 37 publications

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“…In this case, the separated dislocations would slip up continually until the stress concentration cause the cracks formation. The sustained dislocation movement supports the plastic deformation to increase the elongation 40 . In addition, the refined DRXed grains could deform to coordinate the plastic deformation of alloys at high temperatures.…”

Section: Resultsmentioning

confidence: 65%

The improved properties and microstructure of β-solidify TiAl alloys by boron addition and multi steps forging process

Xiao

Chen

et al. 2019

Sci Rep

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A novel forging process has been designed for better mechanical properties of Ti-43Al-6Nb-1Mo-1Cr-(0,0.6)B alloys in this paper. Multi step forging process could provide much finer microstructure, higher room-temperature strength, increased high-temperature strength and elongation with these alloys. The forged alloys without boron exhibit strength and elongation as 676.05 ± 11.37 MPa and 41.32 ± 1.38% at 800 °C, while the average grain size represents as 12.63 ± 3.77 μm. The forged alloys with 0.6 at.% B represent better mechanical properties than the forged alloys without boron, due to the refined microstructure with dispersive borides. Meanwhile, the detailed mechanism of increased strength and elongation caused by finer microstructure were concluded and discussed.

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Section: Resultsmentioning

confidence: 65%

The improved properties and microstructure of β-solidify TiAl alloys by boron addition and multi steps forging process

Xiao

Chen

et al. 2019

Sci Rep

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“…The tensile strength of the TiAl alloy sheet decreases with increasing temperature, whereas the elongation increases continuously ( Figure 11 a,b). At elevated temperatures, the hot-rolled sheet exhibits excellent ductility (for example, at 750 °C, failure strength: 467 MPa, elongation: 53%, which is higher than that of other recently investigated TiAl alloys as shown in Table 2 ) [ 20 , 28 , 41 ]. This excellent high-temperature elongation may be attributed to the uniform microstructure of the sheet, which is conducive for the reduction of stress concentrations, thereby delaying crack formation and propagation during tensile testing at elevated temperatures.…”

Section: Resultsmentioning

confidence: 71%

“…Dynamic recrystallization (DRX) of the hard-deformed γ phase, which only has a limited number of available slip systems, is typically slower than that of the β phase. As the main mechanism for flow softening in the late stages of hot-rolling, γ-phase DRX can soften TiAl alloys during hot-rolling, resulting in grain refinement and reduced resistance to deformation [ 20 ]. Therefore, an understanding of the DRX behavior of the γ phase in the TiAl alloy sheet is essential for further optimization of the hot-rolling process parameters.…”

Section: Introductionmentioning

confidence: 99%

“…In addition, high-density dislocation pile-ups, shear bands, substructures, and twin boundaries are typically formed after hot-rolling [ 21 ]. The difficulty associated with investigating the effect of deformation on high-temperature microstructure is exacerbated by the complex flow behavior of TiAl alloy during hot-rolling [ 20 ]. However, the DRX behavior of the γ phase can be investigated by evaluating the hot-rolling-induced variations in the microstructure.…”

Section: Introductionmentioning

confidence: 99%

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Dynamic Recrystallization of the Constituent γ Phase and Mechanical Properties of Ti-43Al-9V-0.2Y Alloy Sheet

Wang

Kong

et al. 2017

Materials

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Abstract:A crack-free Ti-43Al-9V-0.2Y alloy sheet was successfully fabricated via hot-pack rolling at 1200 • C. After hot-rolling, the β/γ lamellar microstructure of the as-forged TiAl alloy was completely converted into a homogeneous duplex microstructure with an average γ grain size of 10.5 µm. The dynamic recrystallization (DRX) of the γ phase was systematically investigated. A recrystallization fraction of 62.5% was obtained for the γ phase in the TiAl alloy sheet, when a threshold value of 0.8 • was applied to the distribution of grain orientation spread (GOS) values. The high strain rate and high stress associated with hot-rolling are conducive for discontinuous dynamic recrystallization (DDRX) and continuous dynamic recrystallization (CDRX), respectively. A certain high-angle boundary (HAGB: θ = 89 • ± 3 • <100>), which is associated with DDRX, occurs in both the recrystallized and deformed γ grains. The twin boundaries play an important role in the DDRX of the γ phase. Additionally, the sub-structures and sub-boundaries originating from low-angle boundaries in the deformed grains also indicate that CDRX occurs. The mechanical properties of the alloy sheet were determined at both room and elevated temperatures. At 750 • C, the alloy sheet exhibited excellent elongation (53%), corresponding to a failure strength of 467 MPa.

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“…Cheng et al [ 12 ] found that the microstructure evolution was characterized by grain refinement and an increasing fraction of low-angle grain boundaries. Li et al [ 13 ] found different mechanisms have been proposed to explain the superplastic deformation of TiAl-based alloys, which is considered as the combination of dislocation movements, mechanical twinning, and dynamic recrystallization. Many investigations have been conducted to study that the addition of Nb to the alloys, which might slow the domain growth, promote non-basal slip, restrain planar slip, and even reduce antiphase boundary (APB) energy [ 14 , 15 ].…”

Section: Introductionmentioning

confidence: 99%

Superplastic Deformation Mechanisms of Superfine/Nanocrystalline Duplex PM-TiAl-Based Alloy

et al. 2017

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Abstract:In this paper, the equiaxed superfine/nanocrystalline duplex PM-TiAl-based alloy with (γ + α 2 ) microstructure, Ti-45Al-5Nb (at %), has been synthesized by high-energy ball milling and vacuum hot pressing sintering. Superplastic deformation behavior has been investigated at 1000 • C and 1050 • C with strain rates from 5 × 10 −5 s −1 to 1 × 10 −3 s −1 . The effects of deformation on the microstructure and mechanical behaviors of high Nb containing TiAl alloy have been characterized and analyzed. The results showed that, the ultimate tensile strength of the alloy was 58.7 MPa at 1000 • C and 10.5 MPa at 1050 • C with a strain rate of 5 × 10 −5 s −1 , while the elongation was 121% and 233%, respectively. The alloy exhibited superplastic elongation at 1000 and 1050 • C with an exponent (m) of 0.48 and 0.45. The main softening mechanism was dynamic recrystallization of γ grains; the dislocation slip and γ/γ interface twinning were responsible for superplastic deformation. The orientation relationship of γ/γ interface twinning obeyed the classical one: (001) γ //(110) γ .

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Microstructure and high temperature mechanical properties of powder metallurgical Ti-45Al-7Nb-0.3W alloy sheets

Cited by 29 publications

References 37 publications

The improved properties and microstructure of β-solidify TiAl alloys by boron addition and multi steps forging process

The improved properties and microstructure of β-solidify TiAl alloys by boron addition and multi steps forging process

Dynamic Recrystallization of the Constituent γ Phase and Mechanical Properties of Ti-43Al-9V-0.2Y Alloy Sheet

Superplastic Deformation Mechanisms of Superfine/Nanocrystalline Duplex PM-TiAl-Based Alloy

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