Strain rate dependent deformation behavior of BCC-structured Ti29Zr24Nb23Hf24 high entropy alloy at elevated temperatures

Cao, Tangqing; Guo, Wuqian; Wang, Lu; Xue, Yunfei; Lu, Wenjun; Su, Jing; Liebscher, Christian; Li, Chang; Dehm, Gerhard

doi:10.1016/j.jallcom.2021.161859

Cited by 30 publications

(5 citation statements)

References 51 publications

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“…Consistent with prior reports on Group IV–rich RHEAs in tension and compression, EBSD maps (Fig. 3) showed profuse deformation kink bands ( 20 , 21 , 39 – 42 ). However, the role played by kink bands on the overall behavior in the presence of a sharp crack is not established.…”

Section: Resultssupporting

confidence: 91%

Kink bands promote exceptional fracture resistance in a NbTaTiHf refractory medium-entropy alloy

Cook,

Kumar,

Payne

et al. 2024

Science

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Single-phase body-centered cubic (bcc) refractory medium- or high-entropy alloys can retain compressive strength at elevated temperatures but suffer from extremely low tensile ductility and fracture toughness. We examined the strength and fracture toughness of a bcc refractory alloy, NbTaTiHf, from 77 to 1473 kelvin. This alloy’s behavior differed from that of comparable systems by having fracture toughness over 253 MPa·m 1/2 , which we attribute to a dynamic competition between screw and edge dislocations in controlling the plasticity at a crack tip. Whereas the glide and intersection of screw and mixed dislocations promotes strain hardening controlling uniform deformation, the coordinated slip of <111> edge dislocations with {110} and {112} glide planes prolongs nonuniform strain through formation of kink bands. These bands suppress strain hardening by reorienting microscale bands of the crystal along directions of higher resolved shear stress and continually nucleate to accommodate localized strain and distribute damage away from a crack tip.

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Section: Resultssupporting

confidence: 91%

Kink bands promote exceptional fracture resistance in a NbTaTiHf refractory medium-entropy alloy

Cook,

Kumar,

Payne

et al. 2024

Science

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“…Conversely, at lower strain rates, the nucleation of the HCP phase transpires on multiple habit planes [38] . Additionally, lower strain rates are more conducive to defect generation, and defects play a promoting role in the martensitic transformation [39] .…”

Section: Effect Of Strain Rate On Deformation Mechanismsmentioning

confidence: 99%

Dependence of Mechanical Properties and Deformation Behavior of TRIP-FeMnCoCrAl Dual-phase High-entropy Alloy on Grain Size and Strain Rate

Li,

Zhang,

Niu

et al. 2024

ISIJ Int.

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Fe 50 Mn 30 Co 10 Cr 10 dual-phase metastable high-entropy alloys(HEAS) have gained significant attention for their outstanding mechanical properties. However, limited research has explored the relationship between grain size and strain rate sensitivity (SRS) in dual-phase HEAS. Current investigations primarily focus on pure metals and single-phase FCC HEAS. To address this gap, this study examines the impact of grain size on the deformation behavior and SRS of TRIP-(Fe 50 Mn 30 Co 10 Cr 10 ) 97 Al 3 dual-phase HEAS. Two variants of dual-phase HEAS were prepared, distinguished by their grain sizes (2.86 μm, labeled Fine Grain or FG, and 5.25 μm, termed Coarse Grain or CG), via the vacuum melting method. Subsequent tensile tests were conducted at varying strain rates, ranging from 0.001/s to 0.02/s.The findings unveil a robust grain size dependency in the phase transformation and deformation twinning of the (Fe 50 Mn 30 Co 10 Cr 10 ) 97 Al 3 dual-phase HEA during tensile deformation. Within the FeMnCoCrAl HEA system, characterized by a dual-phase structure, both TRIP (Transformation-Induced Plasticity) and TWIP (Twinning-Induced Plasticity) effects intensify with increasing grain size. Additionally, as the strain rate increases, the TRIP effect gradually diminishes while the TWIP effect strengthens. Notably, the strain rate sensitivity index 'm' exhibits a downward trend with an increase in grain size, distinguishing it from the behavior observed in single-phase FCC HEAS. This study conducts an in-depth analysis of grain size's impact on the SRS of (Fe 50 Mn 30 Co 10 Cr 10 ) 97 Al 3 dual-phase HEA, scrutinizing micro-level aspects encompassing phase transformation, deformation twinning, and grain boundary slip. The findings provide essential theoretical insights for designing HEAS tailored for applications requiring high strain rates.

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“…This research advances the application of phase separation in engineering processes for superplastic forming technology. The evolution of grain size also affects the mechanical properties of materials, as demonstrated by the performance of structural parts [16]. In engineering production, a common method to obtain fine grains in materials is through refining grains via cooling deformation, hot deformation, and heat treatment.…”

Section: Introductionmentioning

confidence: 99%

The Constitutive Equation-Based Recrystallization Mechanism of Ti-6Al-4V Alloy during Superplastic Forming

Chang,

Yang

2024

Coatings

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The present paper is concerned with the dynamic recrystallization of the Ti-6Al-4V alloy. Electron Backscatter Diffraction (EBSD) observations are performed after high-temperatures tensile tests, with the temperature ranging from 700 to ~950 °C, and the strain rates varying between 10−4 and 10−2/s. Based on the analysis of flow behavior, the dominant mechanism is identified, and a mechanism map is proposed. In particular, the conditions of 890 °C and strain rates ranging from 10−3 to ~10−2/s serve as the delineating boundary of dynamic recovery (DRV) and dynamic recrystallization (DRX). For superplastic deformation, the dominant softening mechanism is DRV. Consequently, the occurrence of continuous dynamic recrystallization (CDRX) can naturally be ascribed to the process of grain refinement. Then, a multi-scales physical-based constitutive model of CDRX is developed, demonstrating a good agreement is obtained between the experimental and calculated grain sizes, so the above model could be used to describe the grain growth for superplastic deformation. In conclusion, DRV and DRX in the superplastic forming of Ti-6Al-4V are studied in this study, the condition boundaries of their occurrence are distinguished, and a constitutive equation-based CDRX recrystallization mechanism is given, which might be employed in the fracture mechanism research.

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Strain rate dependent deformation behavior of BCC-structured Ti29Zr24Nb23Hf24 high entropy alloy at elevated temperatures

Cited by 30 publications

References 51 publications

Kink bands promote exceptional fracture resistance in a NbTaTiHf refractory medium-entropy alloy

Kink bands promote exceptional fracture resistance in a NbTaTiHf refractory medium-entropy alloy

Dependence of Mechanical Properties and Deformation Behavior of TRIP-FeMnCoCrAl Dual-phase High-entropy Alloy on Grain Size and Strain Rate

The Constitutive Equation-Based Recrystallization Mechanism of Ti-6Al-4V Alloy during Superplastic Forming

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