Simultaneously increasing the strength and ductility of a refractory high-entropy alloy via grain refining

Juan, Chien-Chang; Tsai, Ming–Hung; Tsai, Chien Hsiung; Hsu, Wei-Lin; Lin, Changjian; Chen, Swe-Kai; Lin, Su-Jien; Yeh, Jien‐Wei

doi:10.1016/j.matlet.2016.08.060

Cited by 186 publications

(39 citation statements)

References 10 publications

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“…From the figure, the trend of calculated shear modulus G cal is consistent with the trend of average shear modulus although significantly smaller than G m by~30%. One can observe that the calculated shear modulus of HfNbTaTiZr 32 GPa is in a good agreement with the literature [43]. This indicates that severe lattice distortion in HEAs has a strong solution hardening effect, but Young's modulus was effectively lower.…”

Section: Solution Hardening Mechanismsupporting

confidence: 85%

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Effects of Mo, Nb, Ta, Ti, and Zr on Mechanical Properties of Equiatomic Hf-Mo-Nb-Ta-Ti-Zr Alloys

Tseng

Juan

Tso

et al. 2018

Entropy

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Nowadays refractory high-entropy alloys (RHEAs) are regarded as great candidates for the replacement of superalloys at high temperature. To design a RHEA, one must understand the pros and cons of every refractory element. However, the elemental effect on mechanical properties remains unclear. In this study, the subtraction method was applied on equiatomic HfMoNbTaTiZr alloys to discover the role of each element, and, thus, HfMoNbTaTiZr, HfNbTaTiZr, HfMoTaTiZr, HfMoNbTiZr, HfMoNbTaZr, and HfMoNbTaTi were fabricated and analyzed. The microstructure and mechanical properties of each alloy at the as-cast state were examined. The solid solution phase formation rule and the solution strengthening effect are also discussed. Finally, the mechanism of how Mo, Nb, Ta, Ti, and Zr affect the HfMoNbTaTiZr alloys was established after comparing the properties of these alloys.

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Section: Solution Hardening Mechanismsupporting

confidence: 85%

“…As for the deviation between σ c and σ 0.2 , it might be due to the overestimated shear modulus. Young's modulus of HfNbTaTiZr is 81 GPa reported by Juan et al [43], and, thus, the shear modulus can be calculated to be 31 GPa. This value is obviously smaller than the average shear modulus 43 GPa of HfNbTaTiZr.…”

Section: Solution Hardening Mechanismmentioning

confidence: 66%

Effects of Mo, Nb, Ta, Ti, and Zr on Mechanical Properties of Equiatomic Hf-Mo-Nb-Ta-Ti-Zr Alloys

Tseng

Juan

Tso

et al. 2018

Entropy

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“…In case of high-entropy alloys, Wu et al obtained n ≈ 4 for various equiatomic alloys of Fe-Ni-Co-Cr-Mn system annealed at 1173 K [48]. 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].…”

Section: Discussionsupporting

confidence: 63%

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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“…Senkov et al [20] showed that the tensile strength of this alloy may reach 1150 MPa by retaining~15% of elongation after suitable thermo-mechanical processing. Very good combinations of high tensile strength and elongation have also been reported by other authors [21][22][23]. Excellent compression strength values at elevated temperatures (i.e., 535 MPa at 800 • C or 295 MPa at 1000 • C) were also reported by Senkov et.…”

Section: Introductionsupporting

confidence: 79%

“…HEAs are usually prepared via arc melting processes, which often results in an inhomogeneous dendritic microstructure [15,18,22,[29][30][31][32][33][34][35][36][37][38][39][40]. The dendritic microstructures are usually removed by subsequent heat treatment.…”

Section: Introductionmentioning

confidence: 99%

Microstructure and Mechanical Properties of Sintered and Heat-Treated HfNbTaTiZr High Entropy Alloy

Málek

Zýka

Lukáč

et al. 2019

Metals

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High entropy alloys (HEAs) have attracted researchers’ interest in recent years. The aim of this work was to prepare the HfNbTaTiZr high entropy alloy via the powder metallurgy process and characterize its properties. The powder metallurgy process is a prospective solution for the synthesis of various alloys and has several advantages over arc melting (e.g., no dendritic structure, near net-shape, etc.). Cold isostatic pressing of blended elemental powders and subsequent sintering at 1400 °C for various time periods up to 64 h was used. Certain residual porosity, as well as bcc2 (Nb- and Ta-rich) and hcp (Zr- and Hf-rich) phases, remained in the bcc microstructure after sintering. The bcc2 phase was completely eliminated during annealing (1200 °C/1h) and subsequent water quenching. The hardness values of the sintered specimens ranged from 300 to 400 HV10. The grain coarsening during sintering was significantly limited and the maximum average grain diameter after 64 h of sintering was approximately 60 μm. The compression strength at 800 °C was 370 MPa and decreased to 47 MPa at 1200 °C. Porosity can be removed during the hot deformation process, leading to an increase in hardness to ~450 HV10.

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Simultaneously increasing the strength and ductility of a refractory high-entropy alloy via grain refining

Cited by 186 publications

References 10 publications

Effects of Mo, Nb, Ta, Ti, and Zr on Mechanical Properties of Equiatomic Hf-Mo-Nb-Ta-Ti-Zr Alloys

Effects of Mo, Nb, Ta, Ti, and Zr on Mechanical Properties of Equiatomic Hf-Mo-Nb-Ta-Ti-Zr Alloys

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

Microstructure and Mechanical Properties of Sintered and Heat-Treated HfNbTaTiZr High Entropy Alloy

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