Control of Fe in Al alloys is a severe challenge for the full metal circulation to produce the recycled alloys with mechanical and physical performance as high as the primary alloys. The high restriction of Fe content is mainly due to the deterioration caused by the large-scale Fe-containing intermetallic compounds (FIMCs) in Al alloys. In this paper, recent knowledge gained regarding nucleation, formation, and technical developments on microstructural control and refinement of FIMCs are overviewed. Specific characteristics of the multiple types of FIMCs in Al alloys are presented in two- and three- dimensional (2D and 3D) form. Phase relationships between the FIMCs in different structures, such as primary phase, binary eutectic, and ternary eutectic, formed at different solidification stages are studied. Phase transformations between the FIMCs with or without intermediate phases during the solidification process are examined in different Al alloys, with the mechanisms being clarified. Various approaches to microstructural control of FIMCs are proposed and validated. Significant refinement of FIMCs has been achieved through inoculation of TiB₂ particles that had been previously modified with deliberately interfacial segregation of desirable alloying elements, leading to the development of the novel “compositional templating” concept.

Knowledge about the intrinsic electronic properties of water is imperative for understanding the behaviour of aqueous solutions that are used throughout biology, chemistry, physics, and industry. The calculation of the electronic band gap of liquids is challenging, because the most accurate ab initio approaches can be applied only to small numbers of atoms, while large numbers of atoms are required for having configurations that are representative of a liquid. Here we show that a high-accuracy value for the electronic band gap of water can be obtained by combining beyond-DFT methods and statistical time-averaging. Liquid water is simulated at 300 K using a plane-wave density functional theory molecular dynamics (PW-DFT-MD) simulation and a van der Waals density functional (optB88-vdW). After applying a self-consistent GW correction the band gap of liquid water at 300 K is calculated as 7.3 eV, in good agreement with recent experimental observations in the literature (6.9 eV). For simulations of phase transformations and chemical reactions in water or aqueous solutions whereby an accurate description of the electronic structure is required, we suggest to use these advanced GW corrections in combination with the statistical analysis of quantum mechanical MD simulations.

Whereas bulk zinc oxide (ZnO) exhibits the wurtzite crystal structure, nanoscale ZnO was recently synthesized in the rock salt structure by addition of Mg. Using first-principles methods, we investigated two stabilization routes for accessing rock salt ZnO. The first route is stabilization by Mg addition, which was investigated by considering ZnO–MgO mixed phases. The second route is through size effects, as surface energies become dominant for small nanocrystal sizes. We discovered that the surface energy of rock salt ZnO is surprisingly low at 0.63 J m^–2, which is lower than those of wurtzite and zinc blende ZnO and lower than that of rock salt MgO. We predict that pure rock salt ZnO is stable for nanocrystals smaller than 1.6 nm, and that Mg additions can greatly extend the size range in which the rock salt phase is stable. Both mixed-phase and core–shell models were considered in the calculations. The present approach could be applied to predict the stabilization of many other nanocrystal phases in deviating crystal structures.