A novel equiaxed eutectic high-entropy alloy with excellent mechanical properties at elevated temperatures

Abstract

A Co25.1Cr18.8Fe23.3Ni22.6Ta8.5Al1.7 (at. %) eutectic high-entropy alloy (EHEA) consisting of face-centered-cubic (FCC) and C14 Laves phases was produced by powder metallurgy. The EHEA shows an equiaxed morphology that is different from eutectic lamellar structure. Nanometer L12 phase (4–5 nm) further precipitates in FCC matrix. The microstructure is highly stable upon annealing at 1000°C for 100 h, which leads to attractive high-temperature strength. The fracture behaviour is observed to be modified by the equiaxed Laves phase, which contains microcracks induced by multiple dislocation slips. The diversified cracking modes help to relieve stress concentration and therefore enhance ductility at high temperatures.

Keywords

• nanoscale precipitation
• high-temperature tensile properties
• eutectic high-entropy alloys
• equiaxed structure