29 research outputs found
Designing cobalt-free face-centered cubic high-entropy alloys A strategy using d-orbital energy level
No full textPublisher Copyright: © 2024 The Author(s)High-entropy alloys (HEAs) are promising materials for high-temperature structural applications such as nuclear reactors due to their outstanding mechanical properties and thermal stability. Instead of the trial-and-error method, it is efficient to design and prepare single-phase face-centered cubic (FCC) structured HEAs using semi-empirical phase formation rules. However, almost all of phase formation rules were proposed without taking into account the cobalt-free situation. The HEAs containing cobalt are unsuitable for nuclear applications because of the long-term activation of cobalt. Here, six parameters, d-orbital energy level, valance electron concentration, entropy of mixing, enthalpy of mixing, atom size differences, and parameter of the entropy of mixing (Ω) were calculated to determine the solid solution phase, especially the FCC phase formation rules in cobalt-free HEAs. HEAs of 4 components were arc melted to verify the newly developed phase formation rules. The nanomechanical properties of produced HEAs were evaluated using nanoindentation. Among the six parameters, the d-orbital energy level and valance electron concentration are the critical factors that determine the FCC phase stability in cobalt-free alloys. Interestingly, the d-orbital energy level can be alone used as a benchmark for developing mechanical properties.Peer reviewe
An Energy Balanced and Lifetime Extended Routing Protocol for Underwater Sensor Networks
No full textEnergy limitation is an adverse problem in designing routing protocols for underwater sensor networks (UWSNs). To prolong the network lifetime with limited battery power, an energy balanced and efficient routing protocol, called energy balanced and lifetime extended routing protocol (EBLE), is proposed in this paper. The proposed EBLE not only balances traffic loads according to the residual energy, but also optimizes data transmissions by selecting low-cost paths. Two phases are operated in the EBLE data transmission process: (1) candidate forwarding set selection phase and (2) data transmission phase. In candidate forwarding set selection phase, nodes update candidate forwarding nodes by broadcasting the position and residual energy level information. The cost value of available nodes is calculated and stored in each sensor node. Then in data transmission phase, high residual energy and relatively low-cost paths are selected based on the cost function and residual energy level information. We also introduce detailed analysis of optimal energy consumption in UWSNs. Numerical simulation results on a variety of node distributions and data load distributions prove that EBLE outperforms other routing protocols (BTM, BEAR and direct transmission) in terms of network lifetime and energy efficiency
Body-centered cubic phase stability in cobalt-free refractory high-entropy alloys
No full textCobalt-free refractory high-entropy alloys (RHEAs) are strong contenders for structural materials in nuclear reactors because they do not exhibit cobalt activity under irradiation. The mechanical properties and thermal stability of RHEAs are primarily attributed to the solid solution phase, which is essentially the body-centered cubic (BCC) phase. The BCC phase formation rules thus became the basic criterion in the compositional design of RHEAs. In this paper, the BCC phase formation rules in cobalt-free RHEAs were determined via the calculation of six semiempirical parameters, namely, the entropy of mixing, enthalpy of mixing, atomic size difference, Ω-parameter, d-orbital energy level and valance electron concentration. The mixing enthalpy and atomic size differences are more effective than other semiempirical parameters for predicting BCC phase stability in cobalt-free RHEAs. The presence of aluminum is found to cause a notable alteration in the range of phase stability in cobalt-free RHEAs
Migration and clustering of early-stage irradiation damage in vanadium
No full textA detailed understanding of the irradiation-induced damage evolution is valuable when considering materials for extreme environments, such as in fusion applications. In this work, irradiation-induced pointlike defects and their recovery kinetics in vanadium are studied with positron annihilation spectroscopy. The defects were created with 10 MeV proton irradiation at cryogenic temperatures. Several distinct recovery stages are found, at 60 K, 100 K, 150 to 250 K, and 375 to 475 K. These are interpreted as the motion of self-interstitial atoms, monovacancies, clusters of vacancies and multivacancy-hydrogen complexes. These observations allow for estimating migration barriers for the elementary defects.Peer reviewe
Telmisartan suppresses cardiac hypertrophy by inhibiting cardiomyocyte apoptosis via the NFAT/ANP/BNP signaling pathway
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