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Dual-phase high-entropy alloys strengthened by multicomponent intermetallic nanoparticles represent a unique class of hetero-structured materials with potentially superior mechanical properties for structural applications. Due to the multicomponent chemistries of both nanoparticles and the matrix, as well as the coherent interfaces between them, these alloys can possess excellent strength-ductility combinations over a wide temperature range. This brief viewpoint article gives an overview of the major developments achieved recently. Advantages over other classes of metallic materials as well as limitations in this field are also carefully discussed. The results provide new insights into the development of high-performance structural materials via multicomponent-nanoparticle engineering. Image, graphical abstract [ABSTRACT FROM AUTHOR]

A study was conducted to evaluate the effects of forage-to-concentrate (F:C) ratio and forage particle length (FPL) on intake, duodenal flow, and digestibility of individual AA in the intestine of lactating dairy cows. The experiment was designed as a 4 × 4 Latin square with a 2 × 2 factorial arrangement of treatments using 4 lactating dairy cows (parity 2) with ruminal and duodenal cannulas. Low (35:65) and high (60:40) F:C ratios (dry matter basis) were combined with 2 FPL of alfalfa silage (short vs. long; 7.9 vs. 19.1 mm). Few interactions between F:C and FPL for duodenal flow and intestinal digestibility of AA occurred, but interactions were detected for intakes of several AA. Intake of essential AA and nonessential AA decreased with increasing F:C, and the intake of several individual AA increased or decreased with increasing FPL. Increasing F:C decreased duodenal flows of essential AA, nonessential AA, and microbial AA due to consistent decreased flows of most individual AA (except Glu). Degradability of most individual AA in the rumen was not affected by F:C ratio or FPL except that the degradability of His was greater with high than low F:C diets, and the degradability of Ser was greater with long versus short FPL diets. However, the degradability of individual AA within diet varied considerably. Overall, F:C ratio and FPL did not affect intestinal digestibility of AA and rumen undegradable protein AA, whereas the digestibility of individual AA in the intestine varied considerably regardless of dietary treatment. These results indicate that increasing F:C ratio decreased AA supply due to decreased flow of AA to the duodenum but altering FPL did not affect AA supply. The results also revealed the necessity to consider both the flows and digestibility of individual AA when optimizing ration formulation to meet AA requirements of dairy cows. [ABSTRACT FROM AUTHOR]

Thermally stable high-entropy alloys (HEAs) consisting of a high density of coherent precipitates show a great potential for high-temperature applications. In this work, we systematically investigated the phase stability and coarsening kinetics of L1 2 -type coherent precipitates in a Ni-30Co-13Fe-15Cr-6Al-6Ti-0.1B (at.%) HEA isothermally aged at 800, 900 and 1000 °C. Aged microstructures in the grain interiors under this temperature range were essentially dominated by the uniform precipitation of multicomponent L1 2 (Ni, Co, Fe, Cr) 3 (Ti, Al)-type precipitates. The coarsening kinetics of these intragranular L1 2 precipitates were quantitatively determined, which were adequately characterized by the classical Lifshitz-Slyozov-Wagner model. The activation energy for coarsening was determined to be 378 kJ/mol, which is relatively higher than that of conventional Ni or Co-based superalloys, suggesting a slow elemental diffusion in the HEA matrix. More importantly, the heterogeneous precipitation and the associated metastable phase transformation mechanism along grain boundaries (GBs) were carefully analyzed. Localized chemical heterogeneity was identified within the discontinuous L1 2 phase at the GBs, which thermodynamically destabilizes the L1 2 structure and encourages the formation of brittle Heusler phase. Finally, we establish a unique duplex-aging strategy that can be efficiently utilized for GB stabilization, by which these detrimental intergranular heterostructures can be greatly eliminated, leading to an exceptional resistance to intermediate-temperature embrittlement, along with enhanced tensile strengths. These findings will not only shed light on the precipitation mechanisms in compositionally complex HEAs but also generate new opportunities to the interfacial design of HEAs for advanced high-temperature applications with superior properties. Image, graphical abstract [ABSTRACT FROM AUTHOR]

We developed a novel high-performance L1 2 -strengthened high-entropy alloy (HEA) in the multicomponent Ni-Co-Fe-Cr-Al-Nb system. The phase transformation, mechanical properties and associated deformation behaviors were systematically investigated through combinational analyses involving the three-dimensional atom probe tomography (3D-APT), transmission electron microscopy (TEM) and first-principles calculations. In contrast to conventional alloys that generally strengthened by Ni 3 (Al, Ti)-type precipitates, a high density of coherent L1 2 nanoprecipitates with a new chemical constitution of (Ni, Co, Fe, Cr) 3 (Al, Nb) can be controllably introduced via elaboratively tuning the content of Al and Nb, resulting in a large lattice misfit of ~0.78% that rarely achieved in previous HEAs. The newly developed (Ni 2 Co 2 FeCr) 92 Al 4 Nb 4 HEA enables excellent tensile properties at a large temperature window from room temperature to 870 °C. More remarkably, an anomalous growth in yield strength can be observed at the temperatures above 600 °C, showing a peak yield stress over 720 MPa when deformed at 760 °C, which surpasses most of the previous L1 2 -strengthened HEAs, as well as the commercial superalloys. Detailed TEM analyses revealed that the multicomponent L1 2 precipitates are mainly sheared by the super-partial dislocations, forming superlattice intrinsic stacking fault (SISF) loops coupled with antiphase boundaries (APBs). Such an interesting deformation substructure enables sustained work hardening and produces high tensile strengths at the high temperatures. The underlying mechanisms of those SISF loops were carefully discussed, which could be possibly ascribed to the local elemental segregation on the planner faults. Image, graphical abstract [ABSTRACT FROM AUTHOR]

Abstract We designed a novel nanoparticles-strengthened high-entropy alloy, Ni 30 Co 30 Fe 13 Cr 15 Al 6 Ti 6 , which exhibits excellent strength-ductility combinations at both ambient and cryogenic temperatures. Especially at 77 K, an exceptional strength-ductility synergy can be observed, showing an ultrahigh tensile strength of 1.7 GPa and a large ductility of 51%, accompanied by a distinctive three-stage strain-hardening response. The precipitation-hardening behaviors and deformation micro-mechanisms were carefully investigated by the atom probe tomography and transmission electron microscope. The dynamic formation of nano-spaced stacking faults contributed to improved strain-hardening capacities, resulting in simultaneous enhancements of plastic deformation stability and tensile ductility at such high-strength levels. Graphical abstract Unlabelled Image [ABSTRACT FROM AUTHOR]

Abstract A series of novel Co-free high-entropy alloys (HEAs) were developed by engineering nanoprecipitation in Fe-Ni-Cr-Mn-Al-Ti system, which exhibit a good combination of low cost, high strength and good ductility. The effects of Ti/Al ratio (from 0.6 to 1.7) on phase structures and mechanical properties were carefully investigated. Specifically, the alloy with a high Ti/Al ratio of 1.7 gives a high tensile strength of 1.25 GPa with a good ductility over 20 %, obviously outperforming other Co-free HEAs. The strain-hardening behaviors and deformation micro-mechanisms were analyzed by transmission electron microscope, which reveals the structural origins of their superior mechanical properties. Graphical abstract Unlabelled Image [ABSTRACT FROM AUTHOR]

As a practical way to alleviate energy supply pressure and promote energy efficiency, the integrated energy system has attracted considerable attention worldwide. However, previous work on the integrated energy system does not adequately investigate the flexibility potential hidden in multi-energy coordination, resulting in a lack of flexibility in operational decisions. In this context, a techno-economic framework is urgently needed to take responsibility for improving the flexible performance of the integrated energy system operation. To do so, an operational strategy is developed to fully exploit the inertia characteristics that exist in the transmission of natural gas and heat energy to increase flexibility in energy use and balancing system energy. In the proposed strategy, flexible carbon trading is simulated at different growth rates and base prices through a tiered carbon trading mechanism to effectively investigate and achieve low carbon emissions. To address carbon emissions from an energy application perspective, a hydrogen-doped electric-to-gas process is established, providing new ideas for a low-carbon economy. Simulation results show that the proposed method can improve the accommodation level of renewable energy and reduce carbon emissions, and make more detailed use of the transmission energy of the integrated energy system to achieve more flexible operation. • A techno-economic framework is studied for the flexible operation of an IES. • The energy transmission with inertia characteristics is studied in IES. • The stepped carbon trading mechanism is presented to study carbon emissions. • The hydrogen-doped electric-to-gas process is established for flexible use. [ABSTRACT FROM AUTHOR]