Phase-transition assisted mechanical behavior of TiZrHfTax high-entropy alloys

Shuo Huang; Wei Li; Erik Holmström; Levente Vitos

doi:10.1038/s41598-018-30892-x

Phase-transition assisted mechanical behavior of TiZrHfTa_x high-entropy alloys

Sci Rep. 2018 Aug 22;8(1):12576. doi: 10.1038/s41598-018-30892-x.

Authors

Shuo Huang¹, Wei Li², Erik Holmström³, Levente Vitos^{4

5

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Affiliations

¹ Applied Materials Physics, Department of Materials Science and Engineering, Royal Institute of Technology, Stockholm, SE-100 44, Sweden. shuoh@kth.se.
² Applied Materials Physics, Department of Materials Science and Engineering, Royal Institute of Technology, Stockholm, SE-100 44, Sweden.
³ Sandvik Coromant R&D, 126 80, Stockholm, Sweden.
⁴ Applied Materials Physics, Department of Materials Science and Engineering, Royal Institute of Technology, Stockholm, SE-100 44, Sweden. levente@kth.se.
⁵ Department of Physics and Astronomy, Division of Materials Theory, Uppsala University, SE-75120, Uppsala, Sweden. levente@kth.se.
⁶ Institute for Solid State Physics and Optics, Wigner Research Centre for Physics, H-1525, Budapest, Hungary. levente@kth.se.

Abstract

Recent developments of high-entropy alloys with high strength and high ductility draw attention to the metastability-engineering strategy. Using first-principle theory, here we demonstrate that reducing the Ta level in the refractory TiZrHfTa_x system destabilizes the body-centered cubic (bcc) phase and leads to the appearance of the hexagonal close-packed (hcp) phase embedded in the bcc matrix. The alloying-induced features of the elastic parameters for the cubic and hexagonal structures are mapped out in details, and strong sensitivity to the crystal lattice and chemistry is revealed. Results show softening of the bcc matrix with decreasing Ta concentration which ensures ductile behavior. However, the elastically nearly isotropic hcp precipitates possess enhanced resistance against shear which promotes strengthening of the TiZrHfTa_x dual-phase system. The present atomic-level insight provides strong evidence to the experimental observation, and emphasizes the significance of quantum-design for advanced multi-phase high-entropy alloys with excellent strength-ductility combinations.