First hafnium-based MAX phase in the 312 family, Hf3AlC2: A first-principles study

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Author(s)
Roknuzzaman, M
Hadi, MA
Ali, MA
Hossain, MM
Jahan, N
Uddin, MM
Alarco, JA
Ostrikov, K
Griffith University Author(s)
Year published
2017
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The ground state physical properties of the newly synthesized 312 MAX compound, Hf3AlC2 have been investigated using the first-principles density functional theory (DFT). The optimized unit cell parameters show good agreement with the experimental values. The calculated elastic constants and phonon dispersion confirm the mechanical and dynamical stabilities of this new compound. High bulk modulus, combined with low shear resistance and low Vickers hardness, indicates good machinability of Hf3AlC2, as expected for a metallic compound. On the other hand, significant stiffness due to large Young's modulus as well as the brittle ...
View more >The ground state physical properties of the newly synthesized 312 MAX compound, Hf3AlC2 have been investigated using the first-principles density functional theory (DFT). The optimized unit cell parameters show good agreement with the experimental values. The calculated elastic constants and phonon dispersion confirm the mechanical and dynamical stabilities of this new compound. High bulk modulus, combined with low shear resistance and low Vickers hardness, indicates good machinability of Hf3AlC2, as expected for a metallic compound. On the other hand, significant stiffness due to large Young's modulus as well as the brittle nature according to the calculated Pugh's and Poison's ratios and Cauchy pressure are comparable to that of a ceramic. The present calculations show that Hf3AlC2 is elastically and optically anisotropic. The chemical bonding in Hf3AlC2 consists of a mixture of metallic, covalent and ionic contributions. The calculated Fermi surface contains quasi-two-dimensional topology, which indicates possible superconductivity of Hf3AlC2. The new phase Hf3AlC2 may also be a promising thermal barrier coating (TBC) material. The calculated enthalpy and entropy are found to increase with temperature above 100 K though a decrease is observed for the free energy.
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View more >The ground state physical properties of the newly synthesized 312 MAX compound, Hf3AlC2 have been investigated using the first-principles density functional theory (DFT). The optimized unit cell parameters show good agreement with the experimental values. The calculated elastic constants and phonon dispersion confirm the mechanical and dynamical stabilities of this new compound. High bulk modulus, combined with low shear resistance and low Vickers hardness, indicates good machinability of Hf3AlC2, as expected for a metallic compound. On the other hand, significant stiffness due to large Young's modulus as well as the brittle nature according to the calculated Pugh's and Poison's ratios and Cauchy pressure are comparable to that of a ceramic. The present calculations show that Hf3AlC2 is elastically and optically anisotropic. The chemical bonding in Hf3AlC2 consists of a mixture of metallic, covalent and ionic contributions. The calculated Fermi surface contains quasi-two-dimensional topology, which indicates possible superconductivity of Hf3AlC2. The new phase Hf3AlC2 may also be a promising thermal barrier coating (TBC) material. The calculated enthalpy and entropy are found to increase with temperature above 100 K though a decrease is observed for the free energy.
View less >
Journal Title
Journal of Alloys and Compounds
Volume
727
Copyright Statement
© 2017 Elsevier. Licensed under the Creative Commons Attribution-NonCommercial-NoDerivatives 4.0 International Licence (http://creativecommons.org/licenses/by-nc-nd/4.0/) which permits unrestricted, non-commercial use, distribution and reproduction in any medium, providing that the work is properly cited.
Subject
Condensed matter physics
Materials engineering
Resources engineering and extractive metallurgy
Science & Technology
Physical Sciences
Chemistry, Physical
Materials Science, Multidisciplinary