Annealing effect for the Al0.3CoCrFeNi high-entropy alloy fibers

Abstract High-entropy alloy fibers with excellent performance potential are desired for functional applications. A previous study on the Al 0.3 CoCrFeNi high-entropy fiber reported a tensile fracture strength of 1200 MPa and elongation of 8% at room temperature (Acta Mater. 123 (2017) 285). The goal of this study is to improve the ductility of Al 0.3 CoCrFeNi high-entropy fiber by manipulating the microstructure through annealing. Al 0.3 CoCrFeNi fibers at Φ1.0 mm and Φ1.6 mm diameters were annealed at 900 °C for 10 min, 30 min, 300 min and 720 min, respectively. The resulting microstructure is a fine face-centered cubic (FCC) structure with grain sizes less than ∼3 μm, which were strengthened by dense NiAl-type ordered body-centered cubic (B2) precipitation. The fibers achieved a fracture strength greater than 900 MPa with an elongation of over 25% at room temperature.