Microstructural evolution and mechanical properties of a Cr-rich β-solidifying TiAl-based alloy prepared by electromagnetic cold crucible continuous casting

Liu, Shiqiu; Ding, Hongsheng; Chen, Ruirun; Guo, Jingjie; Fu, Hengzhi

doi:10.1016/j.msea.2020.140205

Cited by 12 publications

(8 citation statements)

References 40 publications

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“…The microstructures of both the C. C. alloy and the 1250 C heattreated alloy have been investigated in previous research, [15,27] their typical backscattered-electron (BSE) images are shown in Figure 1. It is indicated that the microstructures of the C. C. alloy mainly consist of B2/γ lamellar structures matrix and some strip-shaped (B2 þ γ)-coupled structures distributed therein; after the C. C. alloy is heat-treated at 1250 C for 2 h, the volume fraction of lamellar structures increased obviously, and the B2/γ lamellae in the C. C. alloy almost transformed into the conventional α 2 /γ lamellae completely;in contrast, the strip-like coupled structures in the C. C. alloy were significantly reduced.…”

Section: Microstructure Analysismentioning

confidence: 99%

“…Chemical composition [at%] The format of each value for different parameters is mean AE standard deviation; the symbols d, λ, Δ(α 2 /γ) and f(B2 þ γ) represent the grain size, interlamellar spacing, the width ratio of α 2 lamella to γ one for lamellar structures, and the volume fraction of (B2 þ γ)-coupled structures, respectively; some microstructural parameters of the C. C. alloy and the 1250 C heat-treated alloy are referred to in the literature of refs. [15] and [27]. originated from Shockley partial dislocations slipping on two different {111} crystal planes--indicating that such stacking faults or nanotwin embryos underwent complex stress during generation.…”

Section: Samples A)mentioning

confidence: 99%

“…TiAl-based alloys conventionally exhibit cleavage or quasicleavage fracture characteristics during RT tension. [15,27] With respect to cleavage fracture, the Ritchie-Knott-Rice (RKR) model proposes a local criterion for the unstable slip-initiated cleavage ahead of sharp cracks. The criterion requires the local tensile stress to exceed a critical fracture stress over a microstructurally significant characteristic size scale.…”

Section: Relationships Of Fracture Toughness On Tensile Properties An...mentioning

confidence: 99%

“…[23,25] However, limited attention has been paid to the fracture toughness and fracture behavior of TiAl-based alloys with superior deformation twinning ability. To address this gap and on basis of previous researches, [15,27] a series of investigations (including microstructure characterization, fracture toughness measurement, and observation of crack propagation path) were conducted on two samples fabricated by the CCHT method, as well as the continuous casting (C. C.) alloy, which was used for comparison in this research.…”

Section: Introductionmentioning

confidence: 99%

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Improved Fracture Toughness of Polycrystalline γ‐TiAl‐Based Intermetallic Alloys with a Favorable Deformation Mechanism of Twinning

et al. 2022

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High-density deformation nanotwins markedly strengthen TiAl-based alloys; however, the improvement in strength generally leads to a reduction in fracture toughness for most structural materials. It is, therefore, necessary to investigate the benefits of high-density deformation nanotwins for the improvement in fracture toughness of TiAl-based alloys. Herein, the fracture toughness of two Ti-45.5Al-4Cr-2.5Nb alloys with a favorable deformation mechanism of twinning (prepared by annealing the continuous casting (C. C.) alloy at 1250 C and 1270 C for different durations, respectively) is investigated and compared with that of the unannealed continuous casting (C. C.) alloy, in terms of room-temperature (RT) tensile properties and microstructures. It is found that the two heattreated Ti-45.5Al-4Cr-2.5Nb alloys exhibits a higher fracture toughness than the C. C. alloy. Shear ligaments and slip bands are the main toughening mechanisms for the two heat-treated alloys; their generation is closely related to the enhancement in the plastic deformability of lamellar structures. In addition, the increase in (B2 þ γ)-coupled structures is found to impose a negative effect on the toughening of the investigated alloys. High-density deformation nanotwins favor the improvement in fracture toughness of TiAl-based alloys by improving their fracture strength and plastic deformability, while decreasing their workhardening exponent.

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Section: Microstructure Analysismentioning

confidence: 99%

Section: Samples A)mentioning

confidence: 99%

Section: Relationships Of Fracture Toughness On Tensile Properties An...mentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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Improved Fracture Toughness of Polycrystalline γ‐TiAl‐Based Intermetallic Alloys with a Favorable Deformation Mechanism of Twinning

et al. 2022

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“…Directional solidification is used as a special casting technology to control the microstructure of TiAl-based alloys and produce near-net shape components. The lamellar structure of directionally solidified TiAl alloys shows a balanced combination of ductility and strength [ 6 , 7 , 8 ].…”

Section: Introductionmentioning

confidence: 99%

Effect of growth rate on microstructure evolution in directionally solidified Ti–47Al alloy

Liu

Tao

Cai³

et al. 2022

Heliyon

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The microstructures and morphologies of directionally solidified Ti-47Al alloys with different growth rates ranging from 1 to 200 μm/s were investigated using the Bridgman directionally solidified method. The results showed that numerous columnar grains were formed along the growth direction with the onset of directional solidification. With a variation in the growth rate, the solid/liquid interface changed from a flat to cellular and to dendritic interface. The flat-to-cellular interface transition rate of the Ti-47Al alloy varied from 1 to 3 μm/s. When the growth rate was higher than 10 μm/s, the solid/liquid interface showed typical dendritic growth. During the directional solidification process, the main phase of the directionally solidified Ti-47Al alloy was the α phase, which can be attributed to the solute segregation, supercooling of the components, and contamination of the alloy melt by the Y 2 O 3 ceramic shell. After reaching the steady growth state during the directional solidification process, the solidification path of the alloy was: L→α→αþγ→(α 2 þγ) þ γ. With an increase in the growth rate, the primary dendrite spacing (λ) and lamellar spacing (λs) of the alloy decreased gradually.

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Pseudo-twin boundary improves flow stress and cyclic stability of TiAl single crystal

Zhu,

Yi,

Guo

2024

International Journal of Plasticity

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Microstructural evolution and mechanical properties of a Cr-rich β-solidifying TiAl-based alloy prepared by electromagnetic cold crucible continuous casting

Cited by 12 publications

References 40 publications

Improved Fracture Toughness of Polycrystalline γ‐TiAl‐Based Intermetallic Alloys with a Favorable Deformation Mechanism of Twinning

Improved Fracture Toughness of Polycrystalline γ‐TiAl‐Based Intermetallic Alloys with a Favorable Deformation Mechanism of Twinning

Effect of growth rate on microstructure evolution in directionally solidified Ti–47Al alloy

Pseudo-twin boundary improves flow stress and cyclic stability of TiAl single crystal

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