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The AlxCoCrFeNi2.1 (x = 0, 0.3, 0.7, 1.0, 1.3) multi-component high-entropy alloy (HEA) was synthesized by mechanical alloying (MA) and Spark Plasma Sintering (SPS), The impact of the percentage of Al on crystal structure transition, microstructure evolution and mechanical properties were studied. Crystal structure was investigated by X-ray Diffraction (XRD) and Scanning Electron Microscopy (SEM). The results show that with the increasing of Al content, the crystal structure of the alloys gradually transformed from a nanocrystalline phase of FCC to a mix of FCC and BCC nanocrystalline. The hardness was found to increase steadily from 433 HV to 565 HV due to the increase in fraction of BCC nanocrystalline phase. Thus, the compressive fracture strength increased from 1702 MPa to 2333 MPa; in contrast, the fracture strain decreased from 39.8% to 15.6%. [ABSTRACT FROM AUTHOR]

The precipitation behaviors of the topologically close-packed (TCP) phases in the bicrystal DD5 superalloy have been investigated. The results showed that the [001] crystallographic orientations are consistent with that of adjacent grains; however, the direction of the needle-like TCP phases is not consistent with that of the γ phase channels. The angle between needle-like TCP phases and γ phase channels is 45°, but the angle between the needle-like TCP phases of the adjacent grains is equal to the misorientation of the adjacent grains. Furthermore, during long-term aging, the needle-like TCP phases gradually decompose and transform into globular and short rod-like phases. The TCP phases precipitate preferentially in the dendrite. It is difficult to precipitate at the interdendrite/grain boundary, which is caused by the segregation of the constituent elements of the TCP phase to the dendrite. [ABSTRACT FROM AUTHOR]

The exploitation of clean and efficient fire extinguishing materials has substantial implications for improving disaster prevention, mitigation, and relief capabilities, maintaining public safety, and protecting people's lives and property as well as the natural environment. Natural polymer hydrogel with high water containment, excellent film formation, high heat insulation, ecofriendliness, and degradability has huge potential in achieving new breakthroughs for developing clean and efficient fire extinguishing materials and products. In recent years, the exploitation of hydrogel extinguishing materials and the fabrication of products has attracted great attention, gradually replacing traditional fire extinguishing products. In this perspective, an in-depth review of the evolution of hydrogels applied for fire extinguishing and prevention is presented. Firstly, the extinguishing principles of hydrogel extinguishants are explained. Secondly, the preparation strategies and evaluation system of the hydrogel extinguishants are emphatically discussed. Although great progress has been made in developing high-performance hydrogel extinguishants, it remains challenging to develop cost-effective, degradable, and easy-to-use hydrogel extinguishants. Additionally, we highlight the importance of considering the commercial aspects of hydrogel extinguishants. Looking into the future, hydrogel extinguishants are promising, but continued investment in research and development is necessary to overcome the challenges. [ABSTRACT FROM AUTHOR]

To enhance utilization of wastes generated from steelmaking, a BOF slag sample from Ning Steel group in China is treated by oxidizing at 1500 °C for 30 min and then cooled by different methods. The treated samples are characterized, in combination with calculations using FactSage 6.4. XRD results show that iron oxides in BOF slag are converted largely by the oxidation to spinel phases, Fe3O4 and MgFe2O4, which also eliminates free CaO and MgO. EDS analyses show Fe element existing in di-calcium silicate and glass phase, which are Fe3+ ions formed by oxidation. An incorporation of Fe3+ ions into crystal structures has stabilized high temperature polymorph of C2S, β-C2S, and α'-C2S, in the treated slag samples. Fe3+ ions may also act as a network former to facilitate glass formation. This may make it possible for the glass and α'-C2S phase to complement each other, leading to a higher hydraulicity, while the BOF slag, after the spinel separation, is blended in cements. Some suggestions are proposed, based on the present and early studies, to enhance hydraulicity for the BOF slag, as well as grain sizes of spinel phases, which may result in economic and environmental benefits for steel and cement industries. [ABSTRACT FROM AUTHOR]

The sintering process of belite sulphoaluminate cement (CSA 1 The abbreviations used in this essay are listed as below: belite sulphoaluminate cement = CSA, ordinary Portland cement = OPC, C = CaO, S = SiO 2 , A = Al 2 O 3 , F = Fe 2 O 3 , S ¯ = SO 3 , H = H 2 O. 1 ) clinker is still not clear to date. Besides, there are few reports concerning producing CSA by recycled BOF slag. Therefore, the sintering process of CSA was investigated from this perspective and the results can be a reference for BOF slag disposal. Four kinds of CSA clinkers with different additions of BOF slag were sintered at 1300 °C for 30 min. The sintering process was traced by heating microscope and the characteristics were analyzed by XRD, SEM-EDS and TAM Air. The results showed that the sintering degree of CSA clinker could be predicted by analyzing its sintering process. Furthermore, BOF slag could improve the melting state of CSA clinkers due to its composition containing iron oxide, manganese oxide and magnesium oxide. However, expansion was detected when the temperature reached 420 °C, which was arose by combined factors, namely volatilization of CO 2 decomposed from MgCO 3 and the thermal expansion of raw materials itself. The rational ratios of C 2 S, C 4 A 3 S ¯ , C 4 AF in CSA clinker with 14% BOF slag as raw material stood at 50%, 30%, 20% and its early hydration behavior was better than that of ordinary Portland cement (OPC) at the initial 16 h. [ABSTRACT FROM AUTHOR]