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High-temperature creep refers to the slow and continuous plastic deformation of materials under the effects of high temperatures and mechanical stress over extended periods, which can lead to the degradation or even failure of the components' functionality. AlxCr0.2NbTiV (x = 0.2, 0.5, or 0.8) refractory high-entropy alloys were fabricated by arc melting. The effects of Al content on the microstructure of AlxCr0.2NbTiV alloys were studied using X-ray diffraction, scanning electron microscopy, and electron backscatter diffraction. The microhardness, compression properties, and nanoindentation creep properties of AlxCr0.2NbTiV alloys were also tested. The results show that the AlxCr0.2NbTiV series exhibits a BCC single-phase structure. As the Al content increases, the lattice constant of the alloys gradually decreases, and the intensity of the (110) crystal plane diffraction peak increases. Adding aluminum enhances the effect of solution strengthening; however, due to grain coarsening, the microhardness and room temperature compressive strength of the alloy are only slightly improved. Additionally, because the effect of solution strengthening is diminished at high temperatures, the compressive strength of the alloy at 1000 °C is significantly reduced. The creep mechanism of the alloys is predominantly governed by dislocation creep. Moreover, increasing the Al content helps to reduce the sensitivity of the alloy to the loading rate during the creep process. At a loading rate of 2.5 mN/s, the Al0.8Cr0.2NbTiV alloy exhibits the lowest creep strain rate sensitivity index (m), which is 0.0758. [ABSTRACT FROM AUTHOR]

The traditional thermodynamic equation based on heat flow balance without reflecting the variation characteristics of the reaction process. New thermodynamics equation based on energy conservation is established involving multiple complex factors with reaction process, including species, matter mass and heat capacity. The DSC/DTA equation acquired from energy differential equation. The new equation reflects the dynamic Kirchhoff's law and expresses the heat capacity including the integral term and the differential term which both decided by reaction progression. Two kinds of modes with CaCO3 reactions are carried out to verify the equation. The theoretical calculations are well in accord with the experimental data, which validates the accuracy and reliability of the new equation.Reaction process; Thermodynamic equation; DSC/DTA; Thermal capacity

In recent years, the concept of pipeline intelligence, or smart pipelines, has emerged as a promising approach to address various pipeline transmission issues. Intelligent control system requires the variation and thickness of wax deposition inside the crude oil transmission pipeline to make decisions to minimize wax deposition. This study aimed to investigate wax deposition in both polyethylene (PE) and stainless steel (SS) pipes under different water contents, utilizing a custom-designed flow loop apparatus. It was found that the wax-deposit thickness on the surface of the PE test section was thicker (water content lower than 50 vol. %) and then thinner (water content higher than 50 vol. %) than that on the surface of the SS test section. The radial diffusivity and wax mass flux were calculated and proved to be responsible for the behavior variation of wax deposition. The contact angles of oil and water on the PE surface were both larger than those on the SS surface. Experimental investigation was conducted to determine the phase inversion point of oil and water emulsions, which was found to be around 50 vol.%. The results indicated that when water was the bulk phase, greater water adherence to the steel pipe wall resulted in reduced wax deposition on the SS test section. As a result, distinct deposition behaviors were observed both before and after the phase inversion point. [ABSTRACT FROM AUTHOR]