An ab-initio, empirical and experimental study of phase stability of HfTiVYZr refractory high entropy alloy
Phase evolution and stability in an equiatomic quinary HfTiVYZr refractory high entropy alloy (RHEA) was studied. Prediction of phases that may form on the synthesis of the above alloy was made by using (i) Semi-empirical/empirical methods (based on extended Hume-Rothery rules), (ii) CALPHAD and (ii...
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Elsevier
2025-03-01
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| Series: | Journal of Alloys and Metallurgical Systems |
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| author | Vivek Kumar Pandey B. Nageswara Sarma N.K. Mukhopadhyay |
| author_facet | Vivek Kumar Pandey B. Nageswara Sarma N.K. Mukhopadhyay |
| author_sort | Vivek Kumar Pandey |
| collection | DOAJ |
| description | Phase evolution and stability in an equiatomic quinary HfTiVYZr refractory high entropy alloy (RHEA) was studied. Prediction of phases that may form on the synthesis of the above alloy was made by using (i) Semi-empirical/empirical methods (based on extended Hume-Rothery rules), (ii) CALPHAD and (iii) ab-initio methods. Enthalpy of mixing of HfTiVYZr high entropy alloy calculated using the Miedema model (ΔHmix = 7 kJ.mol−1) was close to the proposed range favouring the formation of single-phase solid solution (−10≤ΔHmix≤7kJ.mol−1). However, the size mismatch factor δ(10.37 %) was unfavourable for forming the single-phase solid solution. As per the prediction of the CALPHAD approach, three disordered HCP solid solutions and one C15 type Laves phase (ZrV2) were found to be stable at room temperature, whereas the ordered BCC_B2 phase was identified to be stable above 1273 K. The DFT approach using a variation of the cluster expansion method with fixed composition and cell size was adopted to study the phase stability of this refractory alloy. Enthalpies of mixing of BCC and HCP structures were calculated for the distinct configuration of atoms on the atomic sites using a ten-atom cell. The annealed alloy was examined by XRD, SEM and SEM-EDS. The annealed sample shows the presence of two disordered HCP phases, namely, HCP1 (a = 3.18 ± 0.02 Å, c/a = 1.58) and HCP2 (a = 3.67 ± 0.02 Å, c/a = 1.55), along with a BCC phase (a = 3.16 ± 0.02 Å) and an ordered intermetallic phase (Hf, Zr)V2 (C15 type Laves phase, a = 7.41 ± 0.02 Å), which is in accordance with the theoretical predictions. The SEM-EDS mapping of the annealed sample shows that the major HCP1 phase contains Hf and Zr predominantly along with some Ti. |
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| id | doaj-art-b5e6f5a527f44aa6b6cc0795f388d61d |
| institution | DOAJ |
| issn | 2949-9178 |
| language | English |
| publishDate | 2025-03-01 |
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| spelling | doaj-art-b5e6f5a527f44aa6b6cc0795f388d61d2025-08-20T02:55:45ZengElsevierJournal of Alloys and Metallurgical Systems2949-91782025-03-01910013910.1016/j.jalmes.2024.100139An ab-initio, empirical and experimental study of phase stability of HfTiVYZr refractory high entropy alloyVivek Kumar Pandey0B. Nageswara Sarma1N.K. Mukhopadhyay2Department of Metallurgical Engineering, Indian Institute of Technology (Banaras Hindu University), Varanasi 221005, India; Department of Mechanical Engineering, School of Engineering, Presidency University, Bangalore 560064, India; Corresponding author at: Department of Mechanical Engineering, School of Engineering, Presidency University, Bangalore 560064, India.Department of Metallurgical Engineering, Indian Institute of Technology (Banaras Hindu University), Varanasi 221005, IndiaDepartment of Metallurgical Engineering, Indian Institute of Technology (Banaras Hindu University), Varanasi 221005, IndiaPhase evolution and stability in an equiatomic quinary HfTiVYZr refractory high entropy alloy (RHEA) was studied. Prediction of phases that may form on the synthesis of the above alloy was made by using (i) Semi-empirical/empirical methods (based on extended Hume-Rothery rules), (ii) CALPHAD and (iii) ab-initio methods. Enthalpy of mixing of HfTiVYZr high entropy alloy calculated using the Miedema model (ΔHmix = 7 kJ.mol−1) was close to the proposed range favouring the formation of single-phase solid solution (−10≤ΔHmix≤7kJ.mol−1). However, the size mismatch factor δ(10.37 %) was unfavourable for forming the single-phase solid solution. As per the prediction of the CALPHAD approach, three disordered HCP solid solutions and one C15 type Laves phase (ZrV2) were found to be stable at room temperature, whereas the ordered BCC_B2 phase was identified to be stable above 1273 K. The DFT approach using a variation of the cluster expansion method with fixed composition and cell size was adopted to study the phase stability of this refractory alloy. Enthalpies of mixing of BCC and HCP structures were calculated for the distinct configuration of atoms on the atomic sites using a ten-atom cell. The annealed alloy was examined by XRD, SEM and SEM-EDS. The annealed sample shows the presence of two disordered HCP phases, namely, HCP1 (a = 3.18 ± 0.02 Å, c/a = 1.58) and HCP2 (a = 3.67 ± 0.02 Å, c/a = 1.55), along with a BCC phase (a = 3.16 ± 0.02 Å) and an ordered intermetallic phase (Hf, Zr)V2 (C15 type Laves phase, a = 7.41 ± 0.02 Å), which is in accordance with the theoretical predictions. The SEM-EDS mapping of the annealed sample shows that the major HCP1 phase contains Hf and Zr predominantly along with some Ti.http://www.sciencedirect.com/science/article/pii/S2949917824000889High Entropy AlloyCALPHADDensity Functional TheoryVaccum Arc MeltingCharacterization |
| spellingShingle | Vivek Kumar Pandey B. Nageswara Sarma N.K. Mukhopadhyay An ab-initio, empirical and experimental study of phase stability of HfTiVYZr refractory high entropy alloy Journal of Alloys and Metallurgical Systems High Entropy Alloy CALPHAD Density Functional Theory Vaccum Arc Melting Characterization |
| title | An ab-initio, empirical and experimental study of phase stability of HfTiVYZr refractory high entropy alloy |
| title_full | An ab-initio, empirical and experimental study of phase stability of HfTiVYZr refractory high entropy alloy |
| title_fullStr | An ab-initio, empirical and experimental study of phase stability of HfTiVYZr refractory high entropy alloy |
| title_full_unstemmed | An ab-initio, empirical and experimental study of phase stability of HfTiVYZr refractory high entropy alloy |
| title_short | An ab-initio, empirical and experimental study of phase stability of HfTiVYZr refractory high entropy alloy |
| title_sort | ab initio empirical and experimental study of phase stability of hftivyzr refractory high entropy alloy |
| topic | High Entropy Alloy CALPHAD Density Functional Theory Vaccum Arc Melting Characterization |
| url | http://www.sciencedirect.com/science/article/pii/S2949917824000889 |
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