Amorphization activated by semicoherent interfaces of FCC/BCC HEA multilayers during deformation

Abstract

Eutectic high entropy alloys (EHEAs) are widely advocated materials for overcoming the strength-ductility trade-off due to their abundant heterogeneous interfaces. However, the lack of a full understanding of the plastic carrier-interface interaction mechanism obscures the essential role of the interface in the simultaneous enhancement of strength and ductility. To elucidate the underlying mechanisms from an interface perspective, FCC/BCC multilayers with semicoherent and coherent interfaces were prepared by a magnetron sputtering system. The mechanical properties and microstructure evolution of multilayers were investigated by using nanoindentation, X-ray diffractometer and transmission electron microscopy, respectively. Moreover, the dislocation motion behavior and stress distribution during plastic deformation were analyzed by MD simulation. It is found that the plastic deformation behavior and mechanical properties of EHEAs are sensitive to the heterogeneous interfacial structure. During plastic deformation, the coherent interface facilitates the continuous slip of dislocations, whereas the semicoherent interface promotes amorphization by dislocations pileup. The results are important for understanding the plastic carrier-interface interaction mechanism, and the findings provide new insights for the development of high strength-ductility HEA materials.