Effect of Mo on high entropy Ti-Nb-Zr-Ta alloy: Phase equilibria, microstructure and mechanical properties

Thermal and mechanical properties of Ti-Nb-Ta-Zr high entropy alloys are often influenced by element content and manufacturing routes, producing significant differences between mechanical properties and microstructure. This work presents a Ti-Nb-Ta-Zr alloy in which Mo is added by adjusting the composition with phase equilibria simulation, improving the mechanical properties based on a mixture of two chemi-cally different solid solutions (BCC1 and BCC2). The materials were produced by arc-melting suction casting. Characterization of the dendritic and interdendritic zones was carried out by means of X-ray spectroscopy, indicating the segregation of Ta and Nb in BCC1 and Zr and Ti in BCC2 phases. The dislocation density increased preferentially in the interdendritic Zr-Ti rich zones. The mechanical properties results were re-lated to the chemical differences between the BCC1 and BCC2 lattice parameters induced by the Mo ad-dition. With Mo segregating between both BCC cells, the resulting microstructure increased the yield strength, being confirmed with the kernel average maps, which showed that, after compression tests, the interdendritic zone accumulated a high density of dislocations, resulting in the segregation of Ti and Zr, affecting the mechanical response of Mo containing alloy.& COPY; 2023 Elsevier B.V. All rights reserved.

Automated summary

In this work, the mechanical properties of a Ti-Nb-Ta-Zr alloy were improved by adjusting the composition with phase equilibria simulation and adding Mo. X-ray spectroscopy characterization showed that Ta and Nb segregated in the BCC1 phase, while Zr and Ti segregated in the BCC2 phase. The mechanical properties were related to the chemical differences between the BCC1 and BCC2 lattice parameters induced by the Mo addition.