Cross-kink unpinning controls the medium- to high-temperature strength of body-centered cubic NbTiZr medium-entropy alloy

Eleti, Rajeshwar R.; Stepanov, Nikita; Yurchenko, N.; Zherebtsov, Sergey; Maresca, Francesco

doi:10.1016/j.scriptamat.2021.114367

Cited by 31 publications

(6 citation statements)

References 27 publications

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“…It is unknown to date. In BCC alloys, similar results appear in only a few papers [ 30 , 31 , 32 ]. The yield strength of BCC pure metals and dilute BCC alloys is controlled by a screw dislocation motion through thermally triggered double-kink nucleation [ 21 , 33 , 34 , 35 ].…”

Section: Resultssupporting

confidence: 69%

High-Temperature Mechanical Properties of NbTaHfTiZrV0.5 Refractory High-Entropy Alloys

Liu

Shi

Zhang

et al. 2023

Entropy

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The NbTaHfTiZrV0.5 is a refractory multi-principal-element alloy with high strength and good ductility at room temperature. It is important for possible high-temperature applications to investigate the deformation mechanism of the NbTaHfTiZrV0.5 alloy at different temperatures using tensile tests. In this investigation, the tensile tests were conducted at room temperature to 1273 K on sheet materials fabricated by cold rolling combined with annealing treatments. At 473 K, the NbTaHfTiZrV0.5 alloy exhibited a high tensile ductility (12%). At a testing temperature range of 673~873 K, the ductility was reduced, but the yield strength remained above 800 MPa, which is rare in most other alloys. The TEM investigations revealed that a dislocation slip controlled the plastic deformation, and the degree of deformation was closely related to the dislocation density. The true stress–strain curves of the alloy under different deformation conditions were obtained by tensile deformation at different deformation temperatures (673~873 K) and strain rates (0.001~0.0005 s−1). Experimental results were utilized to construct the parameters of a constitutive model based on a traditional mathematical model to predict the flow behavior at high temperatures. The excellent high-temperature mechanical properties of the NbTaHfTiZrV0.5 alloy will enable it to be used in several engineering applications.

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Section: Resultssupporting

confidence: 69%

High-Temperature Mechanical Properties of NbTaHfTiZrV0.5 Refractory High-Entropy Alloys

Liu

Shi

Zhang

et al. 2023

Entropy

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“…The intersections of these kinks form cross-kinks whose failure requires the formation of point defects, thus conferring high-temperature strengthening to the alloy. [8,18] A sudden drop in strength is then typically observed above 0.5 − 0.6 T m and is associated with the activation of diffusion-controlled mechanisms that defeat the cross-kinking. [18,19] At lower temperatures, the individual kink glide motion itself is inhibited by solutes, adding to the strength.…”

Section: Methodsmentioning

confidence: 99%

Screw vs. edge dislocation strengthening in body-centered-cubic high entropy alloys and implications for guided alloy design

Baruffi

Maresca

2022

MRS Communications

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“…CR resulted in a noticeable increase in strength by 17-35%, in comparison with the as-cast condition. (It should be noted also that the addition of 2.5 vol.% of (Ti, Nb)B reinforcements into the TiNbZr resulted itself in a ~20% increase in strength [26,31,32]) (Figure 3, Table 1). The observed increase in strength can be associated with several reasons.…”

Section: Discussionmentioning

confidence: 97%

“…The (Ti, Nb)B particles were involved in shear straining, due to which the gradual shortening of the fibers to a nearly equiaxed form was observed (Figure 5). It is worth noting that in non-reinforced TiNbZr, the character of dislocation distribution during deformation is much more homogeneous without the formation of obvious shear bands [32].…”

Section: Discussionmentioning

confidence: 99%

Effect of Cold Rolling on Microstructure and Mechanical Properties of a Cast TiNbZr-Based Composite Reinforced with Borides

Ozerov,

Sokolovsky,

Yurchenko

et al. 2024

Metals

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The TiNbZr/(Ti, Nb)B metal matrix composite with 2.5 vol.% of borides was produced by vacuum arc melting. The composite was then cold-rolled to thickness strains of 10, 20, 50, or 80%. In the initial condition, the composite had a network-like microstructure consisting of the soft TiNbZr matrix (dendrites) and the rigid (Ti, Nb)B shell (interdendritic space). In comparison with the as-cast condition, cold rolling increased strength by 17–35%, depending on the thickness strain. After the maximum thickness strain of 80%, yield strength and ultimate tensile strength of the composite achieved 865 and 1080 MPa, respectively, while total elongation was found to be 5%. Microstructural analysis revealed that cold rolling to 50% resulted in the formation of crossing shear bands caused by the considerable difference in deformation behavior of the matrix and reinforcements. Cold rolling to 80% led to the formation of a lamellar-like microstructure comprising the interlayers of the (Ti, Nb)B phase between the TiNbZr laths. The maximum strain (80% cold rolling) shortened the (Ti, Nb)B fibers into nearly equiaxed particles, with a length to diameter ratio of ~2.

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Cross-kink unpinning controls the medium- to high-temperature strength of body-centered cubic NbTiZr medium-entropy alloy

Cited by 31 publications

References 27 publications

High-Temperature Mechanical Properties of NbTaHfTiZrV0.5 Refractory High-Entropy Alloys

High-Temperature Mechanical Properties of NbTaHfTiZrV0.5 Refractory High-Entropy Alloys

Screw vs. edge dislocation strengthening in body-centered-cubic high entropy alloys and implications for guided alloy design

Effect of Cold Rolling on Microstructure and Mechanical Properties of a Cast TiNbZr-Based Composite Reinforced with Borides

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