Deformation mechanism during high-temperature tensile test in an eutectic high-entropy alloy AlCoCrFeNi2.1

• Published in: Materials science & engineering. A, Structural materials : properties, microstructure and processing Vol. 724; pp. 148 - 155
• Main Authors: Zhang, Yaoli, Wang, Xinguang, Li, Jinguo, Huang, Yaqi, Lu, Yiping, Sun, Xiaofeng
• Format: Journal Article
• Language: English
• Published: Elsevier B.V 02.05.2018
• Subjects: Dynamic recrystallization; Eutectic high-entropy alloy; Miedema model calculation; Precipitate phase; Ultra high ductility; Eutectic high-entropy alloy; Miedema model calculation; Dynamic recrystallization; Ultra high ductility; Precipitate phase
• ISSN: 0921-5093; 1873-4936
• DOI: 10.1016/j.msea.2018.03.078

The deformation mechanism of an eutectic high-entropy alloy (EHEA) AlCoCrFeNi2.1 at elevated temperature has been studied by tensile test, microstructure analysis and calculation. The ratio of the FCC and BCC phases has changed greatly after deformation. The formation enthalpies of L12-type Ni3Al and B2-type NiAl are calculated by using Miedema model. Testing and calculation suggest that B2Ⅱprecipitates (NiAl) have a priority in the precipitation order, which is critical to phase change. Besides, TEM results reveal that the function of B2Ⅱ precipitates in FCC matrix during deformation is similar to Orowan by-passing mechanism, and the role of L12,Ⅱ precipitates in B2 matrix is regarded as dislocation cutting. Dynamic recrystallization, occurring in the FCC matrix, reduces stress concentration caused by dislocation motion, but it may be suppressed by B2Ⅱ precipitates. It has been identified that the softening mechanism of dynamic recrystallization and precipitation strengthening have an effect on the high temperature deformation process of the AlCoCrFeNi2.1 EHEA. [Display omitted] •Eutectichigh-entropy alloy exhibits ultra high ductility at elevated temperature.•The dynamic recrystallization takes place in the FCC matrix and it plays a softening role in the deformation process.