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The formulation of binary, ternary, and quaternary supplementary cementitious materials (SCMs) on an optimized silica fume amount using fly ash, ultrafine (MQ), and limestone powders (LS) is the most sustainable approach to recycling these types of solid wastes for durable concrete. The optimum replacement level of 10% silica fume was blended with different replacement levels of 5, 8, 10, and 15% MQ to formulate different ternary mixes to evaluate the filling effect of MQ. Different ternary mixes containing 10% silica fume and 5, 10, and 15% LS were also produced to examine the effectiveness of both ternary mixtures with either MQ or LS. The quaternary mixtures with 10% silica fume optimized with 20% fly ash and 10% MQ or 10% LS were evaluated for compressive strength, chloride permeability, and porosity. The MQ showed the best filling effect compared to LS. The hot curing conditions significantly enhanced the performance of ternary and quaternary mixtures. Two effects of fillers were observed: the diluting effect brought on by replacement levels and the enhanced filling effect. At early curing, the strength loss resulting from the high replacement level was around 39%; however, this drop could be minimized to approximately 7% under hot curing conditions. It has been demonstrated that the binary, ternary, and quaternary systems offer the best solution to the environmental and durability issues caused by cement. The economic analysis highlights that optimized HPC mixtures with SCMs and fillers, particularly the quaternary mix, achieve superior cost-efficiency and mechanical performance, demonstrating their potential for sustainable and high-performance engineering applications.

The directionally solidified eutectic alloy NiAl-(Cr,Mo) is a promising candidate for structural applications at high temperatures, due to its increased creep resistance compared to its single phase B2ordered NiAl counterpart. This system yields an eutectic trough connecting the invariant reactions of the ternary alloys NiAl-Cr and NiAl-Mo. During directional solidification (DS) along this trough the evolved microstructures of the two-phase eutectic is changing from fibrous to lamellar and back to fibrous morphology while increasing and decreasing the amounts of Mo and Cr, respectively. To investigate these effects in the morphology, the phase-field method has proven to be predestined in the last decades. However, as the modeling of quaternary systems is challenging for the simulation with a grand potential based phase-field model, the focus of this work is on the generation of a material model for one defined compound namely NiAl-31Cr-3Mo. The modeling is validated by investigating the microstructure evolution in two- and three-dimensional simulations of the DS process for two different growth velocities and by investigating their undercooling spacing relationships. The evolving microstructures obtained from three-dimensional large-scale simulations are presented and validated with corresponding micrographs from scanning electron microscopy (SEM) of directionally solidified samples with the same growth velocities. The simulation results show the theoretically expected behaviors and are in qualitative and quantitative accordance with DS experiments. The study of NiAl-31Cr-3Mo serves as the basis for a comprehensive data-driven analysis of microstructure properties and system quantities of the entire quaternary material NiAl-(Cr,Mo). With this, an accelerated design of advanced materials is promoted.

The isothermal sections of the Fe-Si-Cr-Al quaternary system at 800 °C with the Fe composition being fixed at 67 at.% and 50 at.% were determined experimentally using optical microscopy, scanning electron microscopy coupled with energy dispersive x-ray spectroscopy, and x-ray diffractometry. Two three-phase regions (BCC-A2 + σ + D0 3 , FeSi + Fe 5 Si 3 + D0 3 ) were found in the isothermal sections at 67 at.% Fe. Phase microstructures of Fe-corner in the quaternary Fe-Si-Cr-Al system were investigated, especially the multiphase regions containing bcc disordered phase and bcc ordered phases. D0 3 occupies almost half of the isothermal section and could maintain equilibrium with all phases (BCC-A2, σ, Fe 5 Si 3 , FeSi) in the isothermal section. One four-phase region (BCC-A2 + σ + Cr 3 Si + D0 3 ) and five three-phase regions (Cr 3 Si + D0 3 + BCC-A2, Cr 3 Si + σ + BCC-A2, Cr 3 Si + D0 3 + σ, Cr 3 Si + Fe 5 Si 3 + D0 3 , FeSi + Fe 5 Si 3 + D0 3 ) were found in the isothermal section at 50 at.% Fe.

The phase relations of the Zn-Al-Co-Sb quaternary system at 450 and 600 °C with Zn fixed at 93 at.% have been determined experimentally by means of scanning electron microscopy coupled with energy dispersive x-ray spectroscopy and x-ray diffraction. Four four-phase regions and three four-phase regions have been confirmed in these isothermal sections at 450 and 600 °C, respectively. The maximum solubilities of Zn in AlCo, Al 5 Co 2 and Al 13 Co 4 are 4.89, 18.98 and 7.85 at.%, respectively. Furthermore, no new ternary and quaternary compounds have been detected in this study.

The 450 and 600 °C isothermal section of the Zn-Al-Ni-Sb quaternary system with Zn being fixed at 93 at.% have been studied experimentally by using x-ray diffraction and scanning electron microscopy coupled with energy dispersive spectroscopy. The solubility of Al in the γ phase is no more than 2.6 and 1.5 at.% at 450 and 600 °C, respectively. As the temperature rises from 450 to 600 °C, the solubility of Zn in the AlSb phase increases from 3.0 to 10.3 at.%. Two four-phase regions and one four-phase region have been confirmed experimentally at 450 and 600 °C. No new ternary and quaternary compounds were found in the study.

In the course of an exploratory study on the quaternary system Na2O-K2O-CaO-SiO2 single crystals of the first anhydrous sodium potassium calcium silicate have been obtained from slow cooling of a melt in the range between 1250 and 1050 °C. Electron probe micro analysis suggested the following idealized molar ratios of the oxides for the novel compound: K2O:Na2O:CaO:SiO2 = 1:1:12:8 (or KNaCa6Si4O15). Single-crystal diffraction measurements on a crystal with chemical composition K1.08Na0.92Ca6Si4O15 resulted in the following basic crystallographic data: monoclinic symmetry, space group P 21/c, a = 8.9618(9) Å, b = 7.3594(6) Å, c = 11.2453(11) Å, β= 107.54(1)°, V = 707.2(1) Å3, Z = 2. Structure solution was performed using direct methods. The final least-squares refinement converged at a residual of R(|F|) = 0.0346 for 1288 independent reflections and 125 parameters. From a structural point of view, K1.08Na0.92Ca6Si4O15 belongs to the group of mixed-anion silicates containing [Si2O7]- and [SiO4]-units in the ratio 1:2. The mono- and divalent cations occupy a total of four crystallographically independent positions located in voids between the tetrahedra. Three of these sites are exclusively occupied by calcium. The fourth site is occupied by 54(1)% K and 46%(1) Na, respectively. Alternatively, the structure can be described as a heteropolyhedral framework based on corner-sharing silicate tetrahedra and [CaO6]-octahedra. The network can build up from kröhnkite-like [Ca(SiO4)2O2]-chains running along [001]. A detailed comparison with other A2B6Si4O15-compounds including topological and group-theoretical aspects is presented.

The 450 °C isothermal sections of the Fe-Si-Sn-Zn quaternary system with Zn composition fixed at 70 and 93 at.% were determined experimentally using optical microscopy, scanning electronic microscopy coupled with energy dispersive X-ray spectroscopy (SEM-EDS), and X-ray diffractometry (XRD). Five four-phase regions were identified in the 70 at.% Zn section, whereas no four-phase region was found in the 93 at.% Zn section. The liquid phase was found to be in equilibrium with almost all phases in the two sections, including the FeSn, FeSi, FeSi2, Γ1, δ, ζ, and α-Fe phases. The solubility of Sn in the ζ, FeSi, and FeSi2 phases was rather limited; however, the maximum solubility of Si in the FeSn phase was 0.5 wt.%. No quaternary compound was found in the study.

The isothermal section of the Zn-Al-Mg-Si quaternary system at 450 °C with Zn fixed at 70 at.% has been determined by means of scanning electron microscopy, energy dispersive spectroscopy and x-ray diffraction. The results show that there exist the following equilibria regions in the isothermal section: Liq. + α-Al + MgZn 2  + Mg 2 Si and Liq. + α-Al + Mg 2 Si + (Si) four-phase regions, and Liq. + α-Al + Mg 2 Si, Liq. + α-Al + MgZn 2 , Liq. + MgZn 2  + Mg 2 Si, Liq. + α-Al + (Si) and Liq. + MgZn 2  + (Si) three-phase regions. Si is almost insoluble in MgZn 2 and α-Al. The maximum solubility of Al and Zn in Mg 2 Si is 1.8 and 6.1 at.%, respectively. The maximum solubility of Al and Si in MgZn 2 is 3.2 and 0.5 at.%, respectively. No ternary and quaternary compounds were found in this study.

In this paper, the isothermal sections of the Zn-Fe-V-Sb quaternary system at 450 and 600 °C with Zn fixed at 93 at.% have been determined experimentally by means of scanning electron microscopy coupled with energy dispersive x-ray spectroscopy and x-ray diffraction. Four four-phase regions and three four-phase regions have been inferred from experimental data in the isothermal section at 450 and 600 °C, respectively. Furthermore, no new ternary and quaternary compounds have been found at those two temperatures.

The adsorption capacity of synthetic NaX zeolite for Pb2+, Cd2+, Cu2+ and Zn2+ in single and multi-component systems were investigated. The effects of electronegativity and hydration energy on the selective adsorption, as well as potential selective adsorption mechanism of the NaX zeolite for Pb2+, Cd2+, Cu2+ and Zn2+ were also discussed. The maximum adsorption capacity order of the heavy metals in the single system was Pb2+ > Cd2+ > Cu2+ > Zn2+, and this could be related to their hydration energy and electronegativity. The values of the separation factors (α) and affinity constant (KEL) in different binary systems indicated that Pb2+ was preferentially adsorbed, and Zn2+ presented the lowest affinity for NaX zeolite. The selective adsorption capacities of the metals were in the order, Pb2+ > Cd2+ ≈ Cu2+ > Zn2+. The trend for the selective adsorption of NaX zeolite in ternary and quaternary systems was consistent with that in the binary systems. Pb2+ and Cu2+ reduced the stability of the Si-O-Al bonds and the double six-membered rings in the NaX framework, due to the high electronegativity of Pb2+ and Cu2+ than that of Al3+. The selective adsorption mechanism of NaX zeolite for the high electronegative metal ions could mainly result from the negatively charged O in the Si-O-Al structure of the NaX zeolite, hence heavy metal ions with high electronegativity display a strong affinity for the electron cloud of the oxygen atoms in the Si-O-Al. This study could evaluate the application and efficiency of zeolite in separating and recovering certain metal ions from industrial wastewater.