Novel high-entropy alloys with high-density ε-D019 and abnormal phase transformation. (1st July 2021)

• Record Type: Journal Article
• Authors: Xia, G.H.; Ma, Z.L.; Xu, Z.Q.; Wang, M.; Cheng, X.W.; Cai, H.N.
• Is Part Of: Scripta materialia. Number 199(2021)
• Publication Date: 2021-07-01
• Subjects: High-entropy alloys -- Precipitation strengthening -- Widmanstätten pattern -- Phase transformation; Materials -- Periodicals; Metallurgy -- Periodicals; Metalen; Legeringen; Materiaalkunde; Metals, metalworking and machinery industries; Metals; Electronic journals; 620.11
• DOI: 10.1016/j.scriptamat.2021.113893
• Languages: English
• ISSNs: 1359-6462

Abstract

Abstract: Precipitation strengthening is considered to be one of the most effective ways to improve engineering structural materials. However, introducing high-density nanoprecipitates in alloys is a big challenge. In this study, novel CoFeNiVTa(Nb) high-entropy alloys (HEAs) with high-density ε-D019 nanoprecipitates featuring Widmanstätten patterns and coherent interfaces with the matrix are developed using the lattice misfit design concept. The highly ordered hexagonal ε-D019 phase is identified as (Co, Ni, Fe)3 (V, Nb, Ta, Fe) by atomic resolution energy dispersive spectrometry and this phase is metastable and can be abnormally transformed into δ-D0a phase instead of η-D024 . The superior thermodynamic stability of the δ phase compared with the ε phase is confirmed by first-principle calculations. High-density ε-D019 precipitates with Widmanstätten patterns contribute to the improved strengthens and friction properties of CoFeNiVTa(Nb) HEAs. Graphical abstract: Image, graphical abstract