Thermal stability of a nanocrystalline HfNbTiZr multi-principal element alloy processed by high-pressure torsion

Hung, Pham Tran; Kawasaki, Megumi; Han, Jae-Kyung; Lábár, János L.; Gubicza, Jenő

doi:10.1016/j.matchar.2020.110550

Cited by 25 publications

(18 citation statements)

References 36 publications

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“…For both samples, the microstructures consisted of nanocrystalline grains with boundaries that were not well defined, as is typical for HPT‐processed materials. [ 24,30,31 ] Furthermore, the formation of nanocrystalline microstructures was confirmed by the selected‐area‐electron‐diffraction (SAED) patterns (inserts in Figure 9a and 10a). Although the grain boundaries were not well defined, an analysis of the DF and STEM images in Figure 9 and 10 gave an approximate grain size following ECAP + HPT of 50 nm for both materials.…”

Section: Resultsmentioning

confidence: 88%

“…Previous studies have reported the formation of a ZrHf-rich phase with an HCP structure and a TaNbrich phase with a BCC structure after an annealing treatment. [11,13,14,30,31]…”

Section: Annealing Effect On Microstructurementioning

confidence: 99%

“…[11,30,31] It has also been found that both TiZrNbHfTa and TiZrNbHf produced via melt synthesis maintain their BCC single-phase structures during subsequent HPT processing. [30,31] The corresponding lattice constant for melt-synthesized TiZrNbHfTa was 3.411 Å, [29] while that for TiZrNbHf was 3.438 Å. [30] These values are slightly higher than those for the BCC phase developed in samples of powder-synthesized M1-ECAP1-HPT and M2-ECAP1-HPT in the present work (Table 5).…”

Section: Xrd Analysis Of Phasesmentioning

confidence: 99%

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Refractory High‐Entropy Alloys Produced from Elemental Powders by Severe Plastic Deformation

Lapovok,

Ferdowsi,

Shterner

et al. 2024

Adv Eng Mater

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A comparative investigation of two fundamentally different approaches for the synthesis, microstructure evolution, and mechanical properties of the refractory‐high‐entropy alloys (RHEA) HfNbTaTiZr and HfNbTiZr was performed. The two methods comprised conventional arc (button) melting, and a powder route based on mechanical alloying and consolidation via severe plastic deformation (SPD). Powder consolidation via SPD involved different ranges of hydrostatic pressure, strain, and temperature. In particular, blended elemental (BE) powder was pre‐compacted and subjected to one or four passes of equal channel angular pressing (ECAP) at 500°C and then ten revolutions of high‐pressure torsion (HPT) at room temperature to an effective strain between 4 and 40. Some samples were then annealed at 500°C for one hour to investigate the thermal stability of the phases. The four ECAP passes at 500ºC did not result in the formation of the BCC phase typical for the program RHEAs despite the presence of interfacial zones between particles and defect‐driven diffusion. Nevertheless, a single ECAP pass was sufficient to create a solid bulk sample for subsequent HPT. After ten HPT revolutions, in contrast to melting route resulting in a predominantly, as confirmed by majority of published research, single BCC phase alloy, both alloys formed new phases comprising on average 82% of a Nb‐rich BCC phase and ∽18% of a ZrHf‐rich HCP phase in M1 alloy, and 85% a Nb‐rich BCC phase and ∽15% of a ZrHf‐rich HCP phase in M2 alloy. After annealing treatment, the volume fraction of BCC phase decreased on average to 75% and volume fraction of HCP phase increased to ∽25% in both alloys. Notably as result of annealing, the BCC phase in M2 alloy was transformed into two BCC phases with different cell parameters. That results in significantly increased hardness by (Hv 150‐200).This article is protected by copyright. All rights reserved.

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Section: Resultsmentioning

confidence: 88%

“…Previous studies have reported the formation of a ZrHf-rich phase with an HCP structure and a TaNbrich phase with a BCC structure after an annealing treatment. [11,13,14,30,31]…”

Section: Annealing Effect On Microstructurementioning

confidence: 99%

Section: Xrd Analysis Of Phasesmentioning

confidence: 99%

See 1 more Smart Citation

Refractory High‐Entropy Alloys Produced from Elemental Powders by Severe Plastic Deformation

Lapovok,

Ferdowsi,

Shterner

et al. 2024

Adv Eng Mater

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show abstract

“…P.T. Hung et al [ 47 ] confirmed the decrease in the hardness of the HfNbTiZr material when after the HPT it is subjected to annealing. H. Shahmir et al [ 46 ] showed that the hardness of the CoCrFeNiMn alloy increases with the number of revolutions.…”

Section: Discussionmentioning

confidence: 99%

“…In most works on HEAs, the authors measured the microhardness of samples before and after the HPT [ 43 , 44 , 45 , 46 , 47 , 48 , 49 , 50 ]. B. Schuh et al [ 45 ] showed that the hardness of the TiZrNbHfTa alloy sample depends not only on the annealing temperature, but also on its duration.…”

Section: Discussionmentioning

confidence: 99%

Phase Transformations Caused by Heat Treatment and High-Pressure Torsion in TiZrHfMoCrCo Alloy

et al. 2023

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In this work the high-entropy alloy studied contained six components, Ti/Zr/Hf/Mo/Cr/Co, and three phases, namely one phase with body-centered cubic lattice (BCC) and two Laves phases C14 and C15. A series of annealings in the temperature range from 600 to 1000 °C demonstrated not only a change in the microstructure of the TiZrHfMoCrCo alloy, but also the modification of phase composition. After annealing at 1000 °C the BCC phase almost fully disappeared. The annealing at 600 and 800 °C leads to the formation of new Laves phases. After high-pressure torsion (HPT) of the as-cast TiZrHfMoCrCo alloy, the grains become very small, the BCC phase prevails, and C14 Laves phase completely disappears. This state is similar to the state after annealing at high effective temperature Teff. The additional annealing at 1000 °C after HPT returns the phase composition back to the state similar to that of the as-cast alloy after annealing at 1000 °C. At 1000 °C the BCC phase completely wets the C15/C15 grain boundaries (GBs). At 600 and 800 °C the GB wetting is incomplete. The big spread of nanohardness and Young’s modulus for the BCC phase and (C15 + C14) Laves phases is observed.

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Effect of Precipitation Behavior on Mechanical Properties of a Nb-Containing CoCrNi-Based High-Entropy Alloy

Zhou

Lin²,

Chen³

et al. 2022

Met. Mater. Int.

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Thermal stability of a nanocrystalline HfNbTiZr multi-principal element alloy processed by high-pressure torsion

Cited by 25 publications

References 36 publications

Refractory High‐Entropy Alloys Produced from Elemental Powders by Severe Plastic Deformation

Refractory High‐Entropy Alloys Produced from Elemental Powders by Severe Plastic Deformation

Phase Transformations Caused by Heat Treatment and High-Pressure Torsion in TiZrHfMoCrCo Alloy

Effect of Precipitation Behavior on Mechanical Properties of a Nb-Containing CoCrNi-Based High-Entropy Alloy

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