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High-entropy alloys (HEAs) have attracted widespread attention from scholars as a new type of material employed in extreme environments. However, as a main kind of HEAs, many face-centered cubic single-phase HEAs are restricted in industrial applications due to their lower yield strength and high cost when containing expensive elements such as Co. In this study, dispersion strengthening by heat treatment was introduced in low-cost Co-free Fe40Mn20Cr20Ni20 HEA to improve its strength, and its high-temperature tensile behavior and constitutive model were studied to explore its potential application at high temperatures. It is found that when subjected to quasi-static room-temperature stretching, the heat-treated sample exhibits a yield strength of 534 MPa and a tensile plasticity of 26.8%. In addition, the tensile behavior of samples after heat treatment was investigated at high temperature (573–873 K) and low strain rate (10−3–10−1 s−1). The results suggest that the yield strength decreases with increasing temperature and decreasing strain rate. Moreover, at 873 K and 10−3 s−1, the electron backscatter diffraction system and x-ray diffraction results of the deformed sample indicate that the softening curve is driven from the recovery of materials. Finally, the flow stress was predicted using the Arrhenius equation and Artificial Neural Network model (ANN), and the two models were assessed using the average absolute relative error and coefficient of correlation (R). The results showed that the ANN had higher accuracy. [ABSTRACT FROM AUTHOR]

In order to find more excellent structural materials resistant to radiation damage, high-entropy alloys (HEAs) have been developed due to their characteristics of limited point defect diffusion such as lattice distortion and slow diffusion. Specially, refractory high-entropy alloys (RHEAs) that can adapt to a high-temperature environment are badly needed. In this study, T i Z r H f N b M o 0.1 RHEAs are selected for irradiation and nanoindentation experiments. We combined the mechanistic model for the depth-dependent hardness of ion-irradiated metals and the introduction of the scale factor f to modify the irradiation-hardening model in order to better describe the nanoindentation indentation process in the irradiated layer. Finally, it can be found that, with the increase in irradiation dose, a more serious lattice distortion caused by a higher defect density limits the expansion of the plastic zone. [ABSTRACT FROM AUTHOR]

The Portevin–Le Chatelier (PLC) effect induced by dynamic strain aging is commonly observed in various alloys. The stress-drop magnitude of serrations and the critical strain at which serrations occur are two pivotal features characterizing serrated flow. This study investigates the temperature (160–460 °C) and strain rate (6 × 10−4 s−1–2 × 10−2 s−1) dependence of the serrated flow behavior in the CoNiV medium-entropy alloy through uniaxial tensile tests. Under the guidance of the mean-field theory, a scale theory has been applied to derive a scale function and scale indices that can be used to predict the distribution of stress drops. A normal PLC behavior of critical strain is fitted using the dislocation pinning model, demonstrating the presence of specific solute atoms conforming to the dislocation pinning model within medium-entropy alloys. [ABSTRACT FROM AUTHOR]

An accurate gravimetric apparatus based on a contactless magnetic suspension microbalance to measure the hydrogen storage capacity for a variety of carbon nanotubes (CNT) is developed. All investigated CNT products possess relatively low hydrogen storage capacities regardless of their synthesis methods, purities, and nanostrucutres.

In this study, the electrochemical behaviour of CrMnFeNi and CrMnFeNiLa0.1 high-entropy alloys (HEAs) in 0.5 M H2SO4 solutions was investigated. Potentiodynamic polarisation curves and electrochemical impedance spectroscopy (EIS) measurements showed that the addition of rare earth element lanthanum has a positive impact in enhancement of corrosion resistance capacity for CrMnFeNi HEAs. The potentiodynamic polarisation curves of the CrMnFeNi and CrMnFeNiLa0.1 alloys exhibit an extensive passive region ((ΔE>1000 mV). Mott–Schottky analysis showed that the donor densities decreased with the addition of La. The possible mechanism regarding the effect of inclusion of La on the dynamic of passivation process was discussed. [ABSTRACT FROM AUTHOR]

Visible pump-THz (tetrahertz) probe measurements were conducted on single wall carbon nanotubes deposited on quartz substrates. The results indicate that the photoexcited nanotubes exhibit localized transport due to Lorentz-type photoinduced localized states from 0.2 to 0.7 Thz.