Channel segregation, which is featured by the strip-like shape with compositional variation in cast materials due to density contrast-induced flow during solidification, frequently causes the severe destruction of homogeneity and some fatal damage. An investigation of its mechanism sheds light on the understanding and control of the channel segregation formation in solidifying metals, such as steels. Until now, it still remains controversial what composes the density contrasts and, to what extent, how it affects channel segregation. Here we discover a new force of inclusion flotation that drives the occurrence of channel segregation. It originates from oxide-based inclusions (Al2O3/MnS) and their sufficient volume fraction-driven flotation becomes stronger than the traditionally recognized inter-dendritic thermosolutal buoyancy, inducing the destabilization of the mushy zone and dominating the formation of channels. This study uncovers the mystery of oxygen in steels, extends the classical macro-segregation theory and highlights a significant technological breakthrough to control macrosegregation.

The six-membered ring (SMR) is a common structure unit for numerous material systems. These materials include, but are not limited to, the typical two-dimensional materials such as graphene, h-BN, and transition metal dichalcogenides, as well as three-dimensional materials such as beryllium, magnesium, MgB2, and Bi2Se3. Although many of these materials have already become ‘stars’ in materials science and condensed-matter physics, little attention has been paid to the roles of their SMR unit across a wide range of compositions and structures. In this article, we systematically analyze these materials with respect to their very basic SMR structural unit, which has been found to play a deterministic role in the occurrence of many intriguing properties and phenomena, such as Dirac electronic and phononic spectra, superconductivity and topology. As a result, we have defined this group of materials as SMR inorganic materials, which opens a new perspective on materials research and development. With their unique properties, SMR materials deserve wide attention and in-depth investigation from materials design, new physical discoveries to target-wizard applications. It is expected that SMR materials will find niche applications in next-generation information technology, renewable energy, space, etc.

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As a popular thermodynamic calculation method for binary alloys, Miedema's model has been applied in many fields. Chou's Model, a new generation of geometric model for ternary and multicomponent alloy systems, overcomes the intrinsic theoretical defects (including symmetric and asymmetric) existing in some original geometric models. Here, by means of combining Miedema's model and Chou's model as well as including the consideration of the excess entropy we attempted to build the new thermodynamic model to evaluate thermodynamic properties of ternary and multicomponent alloying systems in terms of the physical parameters (molar volume, electronegativity, electronic density and melting point) of constituents. Moreover, the activity and interaction coefficients of a wide of components in iron melt have been discussed in details.