Effect of Cold Deformation and Annealing on the Microstructure and Tensile Properties of a HfNbTaTiZr Refractory High Entropy Alloy

Senkov, O.N.; Pilchak, Adam L.; Semiatin, S. L.

doi:10.1007/s11661-018-4646-8

Cited by 127 publications

(44 citation statements)

References 35 publications

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“…In this case moving boundaries do not exist in the same place long enough for nucleation of a chain of the carbides. Similar character of the secondphase particles distribution was recently observed during annealing at different temperatures of a cold-worked HfNbTaTiZr alloy [55].…”

Section: Discussionsupporting

confidence: 84%

“…A similar result (n ≈ 3.5) was obtained by Juan et al [61] during annealing of the HfNbTaTiZr alloy at temperatures between 1473 K and 1623 K. However, in [55] the value of n was found to be 2 or 3 (both values describe the experimental data equally well) for the same HfNbTaTiZr alloy during annealing at 1373 K. A more-commonly observed value of n = 3 is generally associated with the drag of secondphase precipitates or the segregation of low-solubility alloying elements/impurities to grain boundaries. However, the absence of any second phases in HfNbTaTiZr above 1273 K caused the occurrence of normal grain growth with n = 2, which is generally related to normal grain growth in pure systems or solid solutions with high mutual solubility of alloying elements [55]. The grain growth faster than the particle coarsening has been reported for ultrafine grained oxidebearing iron at elevated temperatures [62].…”

Section: Discussionsupporting

confidence: 83%

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Recrystallized microstructures and mechanical properties of a C-containing CoCrFeNiMn-type high-entropy alloy

Klimova

Shaysultanov

Chernichenko

et al. 2019

Materials Science and Engineering: A

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The effect of cold rolling to 80% thickness reduction and annealing at 973-1373 K for 1 h on the microstructure and mechanical properties of a C-containing CoCrFeNiMn high-entropy alloy was studied. Cold rolling significantly strengthened the alloy to the yield strength of 1310 MPa. Annealing at 973 K or 1073 K resulted in incomplete recrystallization of an fcc matrix and M 23 C 6-type carbide precipitations aligned with highly elongated grains/subgrains. Complete recrystallization occurred during annealing at 1173 − 1373 K. The ordered arrangement of the carbides was not observed after annealing at 1273 K or 1373 K. The volume fraction of carbides decreased with increasing the annealing temperature that can be reasonably described by a Thermo-Calc prediction. The coarsening behavior of the microstructure constituents was studied during isothermal annealing at 1173 K for 1-50 h. It was found that the grain growth and the particle coarsening can be expressed by power law functions of annealing time with grain/particle size exponents of about 2 and 3, respectively. An increase in the annealing temperature from 973 K to 1373 K led to a gradual softening of the alloy; the yield strength decreased from 870 MPa to 320 MPa, whereas total elongation increased from 24% to 47%, respectively. Contributions of various strengthening mechanisms into the overall strength of the alloy were discussed.

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Section: Discussionsupporting

confidence: 84%

Section: Discussionsupporting

confidence: 83%

Recrystallized microstructures and mechanical properties of a C-containing CoCrFeNiMn-type high-entropy alloy

Klimova

Shaysultanov

Chernichenko

et al. 2019

Materials Science and Engineering: A

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“…Strength-ductility of BCC-based HEAs. Figure 6 summarizes the data for the BCC-structured HEAs/MEAs 22,[64][65][66][67][68][69][70][71][72] . We observe a strength-ductility trade-off band similar to the yellow one for FCC HEAs in Fig.…”

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confidence: 99%

“…The refractory BCC HEAs that show at least some tensile ductility are compared in Fig. 6, which are mostly based on the Ti-Zr-Hf-Nb-Ta system: the as-cast BCC equiatomic TiZrHfNbTa alloy shows a σ y of~830 MPa 65,66 , which can be further elevated via subsequent cold rolling and annealing 68 , together with a tensile elongation to failure of ∼9%. BCC-MEAs with tensile ductility have also been reported recently 64 , and are included in Fig.…”

mentioning

confidence: 99%

Tailoring heterogeneities in high-entropy alloys to promote strength–ductility synergy

2019

Nat Commun

360

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Conventional alloys are usually based on a single host metal. Recent high-entropy alloys (HEAs), in contrast, employ multiple principal elements. The strength of HEAs is considerably higher than traditional solid solutions, as the many constituents lead to a rugged energy landscape that increases the resistance to dislocation motion, which can also be retarded by other heterogeneities. The wide variety of nanostructured heterogeneities in HEAs, including those generated on the fly during tensile straining, also offer elevated strain-hardening capability that promotes uniform tensile ductility. Citing recent examples, this review explores the multiple levels of heterogeneities in multi-principal-element alloys that contribute to lattice friction and back stress hardening, as a general strategy towards strength–ductility synergy beyond current benchmark ranges.

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“…Some alloys have demonstrated reasonable workability at room temperature allowing cold rolling to a high thickness reduction. However, the number of cold-workable RHEAs is quite limited [23][24][25][26] so far. Most RHEAs have quite low ductility at room temperature even in compression and thus can be processed at high temperatures only [7].…”

Section: Introductionmentioning

confidence: 99%

Laser Beam Welding of a Low Density Refractory High Entropy Alloy

Panina

Yurchenko

Zherebtsov

et al. 2019

Metals

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The effect of laser beam welding on the structure and properties of a Ti1.89NbCrV0.56 refractory high entropy alloy was studied. In particular, the effect of different pre-heating temperatures was examined. Due to the low ductility of the material, laser beam welding at room temperature resulted in the formations of hot cracks. Sound butt joints without cracks were produced using pre-heating to T ≥ 600 °C. In the initial as-cast condition, the alloy consisted of coarse bcc grains with a small amount of lens-shaped C15 Laves phase particles. A columnar microstructure was formed in the welds; the thickness of the grains increased with the temperature of pre-heating before welding. The Laves phase particles were formed in the seams after welding at 600 °C or 800 °C, however, these particles were not observed after welding at room temperature or at 400 °C. Soaking at elevated temperatures did not change the microstructure of the base material considerably, however, “additional” small Laves particles formed at 600 °C or 800 °C. Tensile test of welded specimens performed at 750 °C resulted in the fracture of the base material because of the higher hardness of the welds. The latter can be associated with the bcc grains refinement in the seams.

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Effect of Cold Deformation and Annealing on the Microstructure and Tensile Properties of a HfNbTaTiZr Refractory High Entropy Alloy

Cited by 127 publications

References 35 publications

Recrystallized microstructures and mechanical properties of a C-containing CoCrFeNiMn-type high-entropy alloy

Recrystallized microstructures and mechanical properties of a C-containing CoCrFeNiMn-type high-entropy alloy

Tailoring heterogeneities in high-entropy alloys to promote strength–ductility synergy

Laser Beam Welding of a Low Density Refractory High Entropy Alloy

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