Structure characterization of special boundaries in Fe47Mn30Co10Cr10B3 dual-phase high-entropy alloy

Abstract

Special boundaries subdivide grain size and change grain orientation, affecting mechanical properties of metallic materials. In this work, in-depth characterization techniques at various length scales are utilized to investigate the special boundaries (twinning boundary and interphase boundary) in dual-phase (face-centered cubic and hexagonal close-packed, FCC + HCP) high-entropy alloy (Fe47Mn30Co10Cr10B3). For twinning boundary, the coherent {111} boundary and the incoherent {112} boundary with 9R structure are systematically investigated. Multiple and single twin variants in FCC matrix can be observed. For interphase boundary, the coherent heterophase interface (FCC-HCP) is consistent with (111)//(0001) close-packed plane orientation, whereas, the stepped-like homophase interface (HCP-HCP) is consistent with (0001)//(101¯1) basal–pyramidal plane orientation. The number of HCP variants is affected by the FCC grain sizes.