Outstanding tensile properties of a precipitation-strengthened FeCoNiCrTi0.2 high-entropy alloy at room and cryogenic temperatures. (15th February 2019)

• Record Type: Journal Article
• Authors: Tong, Y.; Chen, D.; Han, B.; Wang, J.; Feng, R.; Yang, T.; Zhao, C.; Zhao, Y.L.; Guo, W.; Shimizu, Y.; Liu, C.T.; Liaw, P.K.; Inoue, K.; Nagai, Y.; Hu, A.; Kai, J.J.
• Is Part Of: Acta materialia. Volume 165(2019)
• Page Start: 228
• Page End: 240
• Publication Date: 2019-02-15
• Subjects: High-entropy alloys -- Precipitation strengthening -- Deformation mechanism -- Stacking fault; Materials -- Periodicals; Materials science -- Periodicals; Materials -- Mechanical properties -- Periodicals; Metallurgy -- Periodicals; Chemistry, Inorganic -- Periodicals; 620.112
• DOI: 10.1016/j.actamat.2018.11.049
• Languages: English
• ISSNs: 1359-6454

Abstract

Abstract: A FeCoNiCrTi0.2 high-entropy alloy strengthened by two types of coherent nano-precipitates but with the same composition was fabricated, and its tensile properties at room (293 K) and cryogenic temperatures (77 K) and the corresponding defect-structure evolution were investigated. Compared with the single-phase FeCoNiCr parent alloy, the precipitation-strengthened FeCoNiCrTi0.2 high-entropy alloy exhibits a significant increase in yield strength and ultimate tensile strength but with little sacrifice in ductility. Similar to the single-phase FeCoNiCr high-entropy alloy, the deformation behavior of this precipitation-strengthened FeCoNiCrTi0.2 high-entropy alloy shows strong temperature dependence. When the temperature decreases from 293 K to 77 K, its yield strength and ultimate tensile strength are increased from 700 MPa to 860 MPa and from 1.24 GPa to 1.58 GPa, respectively, associated with a ductility improvement from 36% to 46%. However, different from the single-phase FeCoNiCr high-entropy alloy with a twinning-dominant deformation mode at 77 K, multiple-layered stacking faults with a hierarchical substructure prevail in the precipitation-strengthened FeCoNiCrTi0.2 high-entropy alloy when deformed at 77 K. The mechanism of twinning inhibition in this precipitation-strengthened high-entropy alloy is the high energy barrier for twin nucleation in the ordered γ′ nano-particles. Our results may provide a guide for the design of tough high-entropy alloys for applications at cryogenic temperatures through combining precipitation strengthening and twinning/stacking faults. Graphical abstract: Image 1