Dual heterogeneous structures lead to ultrahigh strength and uniform ductility in a Co-Cr-Ni medium-entropy alloy

• DOI: 10.1038/s41467-020-16085-z
• Publication Date: 2020-05-13T10:02:50Z
• Authors: X. H. Du; W. P. Li; H. T. Chang; T. Yang; G. S. Duan; B. L. Wu; J. C. Huang; F. R. Chen; C. T. Liu; W. S. Chuang; Y. Lu; M. L. Sui; E. W. Huang
• Keywords: Ductility (Earth science); Elongation; Nanometre; High-Entropy Alloys

Abstract Alloys with ultra-high strength and sufficient ductility are highly desired for modern engineering applications but difficult to develop. Here we report that, by a careful controlling alloy composition, thermomechanical process, microstructural feature, Co-Cr-Ni-based medium-entropy (MEA) dual heterogeneous structure of both matrix precipitates can be designed provide an tensile 2.2 GPa uniform elongation 13% at ambient temperature, properties that much improved over their counterparts without the structure. Electron microscopy characterizations reveal structures composed coarse grains (10∼30 μm) ultra-fine (0.5∼2 μm), together L1 2 -structured nanoprecipitates ranging from several hundreds nanometers. The fully coherent matrix, minimizing elastic misfit strain interfaces, relieving stress concentration during deformation, playing active role in enhanced ductility.