Phase stability and microstructure evolution in a ductile refractory high entropy alloy Al10Nb15Ta5Ti30Zr40

This paper reports the microstructural evolution and phase stability in a newly developed low-density Al10Nb15Ta5Ti30Zr40 refractory high entropy alloy (RHEA) at different temperatures. This alloy composition was adapted from the composition of the B2 phase in a two-phase B2+BCC mixture at 1000°C in...

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Bibliographic Details
Published in:Materialia 2020-03, Vol.9, p.100569, Article 100569
Main Authors: Soni, V., Senkov, O.N., Couzinie, J.-P., Zheng, Y., Gwalani, B., Banerjee, R.
Format: Article
Language:English
Subjects:
High entropy alloy
Microstructure
Phase composition
Refractory alloy
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Summary:This paper reports the microstructural evolution and phase stability in a newly developed low-density Al10Nb15Ta5Ti30Zr40 refractory high entropy alloy (RHEA) at different temperatures. This alloy composition was adapted from the composition of the B2 phase in a two-phase B2+BCC mixture at 1000°C in the refractory high entropy superalloy Al0.25NbTaTiZr. After homogenizing at a high-temperature, followed by fast or slow cooling to room temperature, this alloy exhibited a nano-scale mixture of co-continuous BCC and B2 phases, resembling a spinodally decomposed microstructure with concurrent ordering. Interestingly, this novel nano-scale BCC+B2 microstructure exhibits excellent room temperature compressive yield strength (~1075MPa) and ductility (true strain at failure ~0.55). Annealing at 600°C and 750°C resulted in the formation of additional ordered omega type AlZr2 phase in this alloy. The experimentally observed phase evolution is in fair agreement with CALPHAD predictions. [Display omitted]
ISSN:2589-1529
2589-1529
DOI:10.1016/j.mtla.2019.100569