Development of the γ′ phase strengthened high-temperature high-entropy alloys with excellent mechanical properties

In this work, a series of novel gamma' phase strengthened Ti6Al6-based HEAs with six kinds of alloying elements (including Nb, Hf, Ta, W, Mo, and V) were carefully examined combined with TEM, SEM, XRD, and DSC technologies. The impurities Fe2X (X = Nb, Hf, and Ta) Laves were detected in the Nb-, Hfand Ta-doping alloys while the other three present a perfect (gamma + gamma') dual-phase microstructures. And the W-, Mo- and V-doping HEAs possess a much better strength-plasticity combination than the Ti6Al6 alloy at room- and high-temperature. The 1.5 W HEA has a tensile strength of similar to 1300 MPa and good plasticity (>30 %) at room temperature. In the meantime, it also performs much good at 800 degrees C (similar to 11 % elongation and the tensile strength of similar to 750 MPa). The addition of W, Mo, and V elements causes the main peak of the HEAs to shift to the left to varying degrees, among which the biggest shift is 1.5 V HEA, followed by 1.5Mo HEA, the smaller is the 1.5 WHEA. At the same time, the gamma' precipitates phase of the alloy has a highly coherent relationship with the FCC matrix phase, which ensures that the strength of the alloy is increased without sacrificing its plasticity. (C) 2022 The Authors. Published by Elsevier Ltd.

Automated summary

In this study, a series of novel gamma' phase strengthened Ti6Al6-based HEAs with six different alloying elements were examined. The presence of impurity phases and the microstructure of the alloys were investigated using various characterization techniques. The addition of W, Mo, and V elements improved the strength-plasticity combination of the HEAs at both room temperature and high temperature. The peak position of the alloys shifted to the left with the addition of W, Mo, and V elements. The coherent relationship between the gamma' precipitates phase and the FCC matrix phase contributed to the increased strength of the alloys without sacrificing plasticity.