Plastic deformation and strengthening mechanism in CoNiV medium-entropy alloy fiber

High/medium-entropy alloys (H/MEAs) are regarded as a potentially viable alternative to conventional metallic fibers for the production of ductile, high-strength fibers, to resolve the inherent trade-off between strength and ductility. The present study involved the cold drawing technique to produce a CoNiV MEA fiber measuring 300 μm in diameter with a length of more than 3 m. The mechanical properties of the FCC matrix can be improved through the inclusion of an appropriate amount of the κ phase via the optimized thermal treatment process. In addition to a yield strength of 1681 MPa and a well-coordinated elongation of 13.4 %, the ideal CoNiV fiber demonstrated a substantial ultimate tensile strength of 1932 MPa. Further calculations revealed that the κ phase, which possesses a substantial Von Mises stress of approximately 2715 MPa and an area fraction of 18.2 ± 1.1 %, was observed to be a primary contributor to the strength. Deformation twins were generated in the FCC matrix as a result of the ultra-high flow stress, which provided adequate ductility. This study offers significant contributions to the understanding of the deformation mechanisms and strengthening effect of the κ phase, thereby facilitating the development of high-performance metallic fibers.