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The virtual water strategy (VWS) is an effective tool to balance regional water resource endowments and guarantee water supply security. However, because of self‐interested games around VWS (human decision bias), there is a need for methods to maintain reliable cooperation between governments, virtual water (VW) enterprises and research institutions. This study builds a multi‐agent evolutionary game model to analyse the relationship of players and their impacts on VWS through changing decision mechanisms and the paths to enhance their confidence in cooperation. Considering differences in initial willingness to cooperate and changing factors affecting payoffs, an evolutionary game can produce changing stable equilibriums or stable cooperations, even if some players are reluctant to cooperate. Therefore, to promote the development of VWS, a multistep support mechanism can be built for the VW industry, which fosters model enterprises and optimizes the cooperation framework to stimulate research innovations at scientific institutions. Highlights: Traditional virtual water strategy (VWS) studies ignored the specific implementation and stakeholder game issues.A multi‐agent evolutionary game model is built to analyse the stable states and decision mechanisms for VWS.The payoffs of each game player will affect its strategy choice and the speed of model evolution.It is clearly possible for the stakeholders to form a stable equilibrium of long‐term cooperation around the VWS.Changing the factors of one game player may indirectly lead to changes in the strategies of other players. [ABSTRACT FROM AUTHOR]

The size and distribution of the silicon phase and intermetallic phase are important factors affecting the properties of Al11Si3Cu2NiMg alloy (M142). In this study, BNNS and micro-TiB2 were used to synergistically refine and reinforce M142 composites (M142-BNNS-TiB2). After T6 heat treatment, the comprehensive mechanical properties of M142-BN-TiB2 composites were excellent, with an ultimate tensile strength of 463 MPa and an elongation of 2.6%. In addition, the introduction of BNNS and micro-TiB2 changed the fracture mode of M142 from brittle fracture to quasi-cleavage fracture, and the introduction of BNNS and micro-TiB2 refined the Si phase and intermetallic phase, which could change the origin of the crack in the composite, thus improving the ductility of the composite. [ABSTRACT FROM AUTHOR]

Deformation twins (DTs) and stacking faults (SFs) are rarely found in Cu-20Ni-20Mn alloy, which limits further strengthening of alloy. Here, we report ultra-strong Cu-20Ni-20Mn alloy prepared by introducing a high density of coherent nanoprecipitates. The ultimate tensile strength (UTS) of alloy can be largely enhanced to 1624.7 ± 14.7 MPa, while maintaining an acceptable elongation of 7.3 ± 0.5%. We find that the coherent nanoprecipitates contribute to an ultra-high true stress up to about 1740 MPa, which facilitate the formation of DTs. The strength and ductility improvement stems from the synergistic effect of dislocations, nanoprecipitates and DTs. The Cu-20Ni-20Mn alloy sheet exhibiting an unprecedented strength-ductility synergy has been prepared by a two-step rolling process. The ultrafine grain structure containing substantial deformation twins coupling with homogeneously distributed nano-coherent precipitates accounts for the superior mechanical properties. [ABSTRACT FROM AUTHOR]

In this work, SnBiAg-xSb solder alloys (where x = 0, 0.5 wt.%, 1.0 wt.%, 1.5 wt.%, 2.0 wt.%, and 2.5 wt.%) were prepared by compression and annealing treatment following water cooling. The microstructure of the SnBiAg-xSb alloy became finer due to the addition of a small amount of Sb. When the Sb content exceeded 1.0 wt.%, the effect of grain refinement decreased, and the grain gradually became coarser with the addition of Sb. As the Sb content increased, the tensile strength of SnBiAg-xSb solder alloys gradually increased while elongation decreased, which was attributed to the solution strengthening of Sb and subsequent microstructural changes. SnBiAg-0.5Sb showed the best elongation at break, reaching a value of 119.12%. Sb increased the starting temperature of the solder during solidification and cooling, expanding the range of the mushy temperature zone. The addition of a small quantity of Sb had a minimal effect on the solder's wettability. The bonding performance of SnBiAg-xSb solder joints before and after aging was studied, and it was found that SnBiAg-2.0Sb solder joints had the strongest bonding strength. [ABSTRACT FROM AUTHOR]

Oxygen evolution reaction (OER) remains a bottleneck for electrocatalytic water‐splitting to generate hydrogen. However, the traditional adsorbed evolution mechanism (AEM) possesses sluggish reaction kinetics due to the scaling relationship, while lattice oxygen mechanism (LOM) triggers an unstable structure due to the escaping of lattice oxygen. Herein, a proof‐of‐concept Fe‐Co(OH)2/Fe2O3 heterostructure is put forward, where Fe‐Co(OH)2 following AEM can complete rapidly deprotonation process while Fe2O3 following LOM can trigger O─O coupling step. Combining the theoretical and experimental investigation confirmed that the redistributed space‐charge of Fe‐Co(OH)2/Fe2O3 junction can optimize synergistically adsorbed and lattice oxygen, the coupling mechanism of AEM and LOM can facilitate synchronously the OER activity and stability. As a result, the Fe‐Co(OH)2/Fe2O3 heterostructure shows excellent OER performance with low overpotential of only 219 and 249 mV to reach a current density of 10 and 100 mA cm−2. Specifically, the Fe‐Co(OH)2/Fe2O3 electrocatalyst maintains excellent long‐term stability for 100 h at a large current density of 100 mA cm−2. This work paves an avenue to break through the limit of the conventional OER mechanism. [ABSTRACT FROM AUTHOR]

Traditionally, metal matrix composites reinforced with uniformly dispersed carbon nanotube (CNT) have shown significant enhancement in strength, but always accompanied by the deterioration of uniform elongation (UE). Herein, a novel strategy is proposed to achieve the prominent strength–ductility combination of CNT‐reinforced Cu composites. The strategy makes use of the architecture design via mixing the CNT/Cu composite powders (prepared by the molecular‐level mixing method) with coarse‐grained Cu powders. The bulk composites with a controlled inhomogeneous microstructure are designed and fabricated, in which the reinforcing phase is inhomogeneously distributed at the microscale but homogeneous at the macroscale. The effects of fine and coarse grain proportions on the microstructure evolution and plastic deformation capacity of bimodal‐grained Cu composites are investigated. When the mixed ratio of refined CNT/Cu powder to coarse‐grained Cu is 1:1, the ultimate tensile strength (UTS) and UE of bimodal‐grained Cu composites are 384 MPa and 26.9%, respectively. Such good strength–plasticity compatibility is attributed to the combined effects of hetero‐deformation‐induced (HDI) stress and CNT strengthening mechanisms. This study provides insights for evading the strength–ductility trade‐off in high‐performance metal matrix composite by architecture design. [ABSTRACT FROM AUTHOR]

Laminated metal composites have attracted more attention due to their ultra-high strength, fracture toughness and elongation, full considerations of each component, and coordinated deformation effect between interfaces. Herein, Zn and Al were selected as the component materials to prepare Al/Zn laminated composite plates using hot rolling and low temperature annealing, and studied the influence of the thickness of the diffusion layer at the interface to understand the reason for the strengthening and toughening mechanism. The results show that, with an increase in annealing temperature and time, the grain will recover and recrystallize to grow. A diffusion layer with a certain thickness formed at the interface due to the mutual diffusion of Al and Zn atoms at the interface. As annealing time and temperature increase, the yield and tensile strengths first increased and then decreased. The tensile fracture morphology showeds many deep dimples. In the rolling state, the micro-hardness value at the interface was between Al and Zn. [ABSTRACT FROM AUTHOR]

The homogeneous distribution of carbon nanotubes (CNTs) in the Cu matrix and good interfacial bonding are the key factors to obtain excellent properties of carbon nanotube-reinforced Cu-based composites (CNT/Cu). In this work, silver-modified carbon nanotubes (Ag-CNTs) were prepared by a simple, efficient and reducer-free method (ultrasonic chemical synthesis), and Ag-CNTs-reinforced copper matrix composites (Ag-CNTs/Cu) were fabricated by powder metallurgy. The dispersion and interfacial bonding of CNTs were effectively improved by Ag modification. Compared to CNTs/Cu counterparts, the properties of Ag-CNTs/Cu samples were significantly improved, with the electrical conductivity of 94.9% IACS (International Annealed Copper Standard), thermal conductivity of 416 W/m·k and tensile strength (315 MPa). The strengthening mechanisms are also discussed. [ABSTRACT FROM AUTHOR]

Sn–Zn lead-free solder alloy is seriously restricted in the applications of electronic equipment and circuit boards due to the poor wettability and corrosion resistance. The alloying method is considered as the most effective way to improve the performance of this solder. In the present study, a new alloying method within the high-throughput, dual-target co-sputtering deposition was employed to produce the Ag-doped Sn–9Zn solder thin films with a uniform Ag gradient ranging from 0.2 to 9.58 wt.%. The results revealed that the hardness and Young’s modulus of the solder thin films increased with the decrease of Ag content. The oxidation resistance remained constant at first, then decreased rapidly when the Ag content was too low to uniformly disperse in the Sn–Zn matrix. Based on the above results, Sn–Zn alloy blocks with different Ag contents were prepared, and then the microhardness and oxidation behavior of these blocks were analyzed. It is explained how Ag affects the Sn–Zn lead-free solder alloy’s mechanical characteristics and oxidation resistance. This study provided an effective approach for developing a new alloy with many components fast. [ABSTRACT FROM AUTHOR]

Element segregation in the as-cast medium-entropy alloy (MEA), CrCoNiAl0.014, has a significant influence on its mechanical properties. This study focused on aluminum segregation in the as-cast CrCoNiAl0.014 MEA at room temperature (300 K). The element distribution, morphology, and type of precipitates formed by the elemental segregation were identified by optical microscopy, X-ray diffraction, electron probe microanalysis, and transmission electron microscopy. Al segregation existed at the dendritic boundary in the face-centered cubic (FCC) MEA matrix. Hybrid molecular dynamics and Monte Carlo simulations were conducted to analyze the diffusion behavior and the chemical affinity of Al, as well as understand the segregation mechanism of Al at the atomic scale. Al displayed a faster diffusion speed and a higher chemical affinity than Ni, Cr, and Co at the same temperature. Al segregated at the dendritic boundary to form the Al-rich phase. Furthermore, as the temperature was increased, the atomic thermal vibration of these four elements became more intensive, and Al segregation was more serious. However, Al segregation improved the uniform diffusion of Cr, Co, and Ni. Therefore, this study provides a reference for subsequent reductions in element segregation and improvements in the mechanical properties of MEA. [ABSTRACT FROM AUTHOR]

In-situ observation of the growth and decomposition processes is significantly important for guiding the fabrication of up-conversion nanocrystals (UCNCs) with high performance. However, the high crystallization energy and rapid nucleation rate of the corresponding crystals make real-time observation still a huge challenge. Herein, the in-situ nucleation-growth-degradation processes of the UCNCs are investigated by employing tailored metastable intermediates, which possess a slowing-down nucleation rate under electron beam irradiation. The non-classical nucleation processes of the UCNCs, containing the coalescence of clusters and the subsequent crystallization, are demonstrated. Moreover, the Ostwald ripening and oriented attachment processes, which determine the particle size and morphology, are unambiguously recorded. Furthermore, the degrading process of the UCNCs is observed to be triggered by surface defects. Our work provides an insight into the real-time evolution dynamics of the UCNCs, which further sheds light on the fabrication of nano-sized up-conversion phosphors. [ABSTRACT FROM AUTHOR]

The Zr50−x/2Co50−x/2Alx (x = 0, 4, 5, 6, 7, 8) alloy sheets were prepared by copper mold suction casting, and the effect of Al content on the mechanical properties and the strengthening mechanism was thoroughly investigated. With Al addition, a Zr5Co7Al3 intermetallic compound formed and precipitated at the grain boundaries or inside the grains, which produced strong synergistic effects of secondary phase strengthening, fine grain strengthening and solid solution strengthening. However, the precipitation of intermetallic compounds can lead to the formation of shrinkage cavities at grain boundaries, and the negative effect of adding too much Al is greater than the strengthening effect, resulting in a gradual decrease in strength. Therefore, the best synergistic strengthening effect is achieved when the Al content is 5 at.%, the grain size of the alloy is reduced from 60 μm to 4 μm, and the room temperature tensile strength is increased from 240 MPa to 464 MPa. [ABSTRACT FROM AUTHOR]

In the present work, the effects of Bi addition on the microstructure, solderability, and mechanical properties of Sn-Zn-Cu lead-free solder were studied. The composition of Sn-Zn-Cu-Bi solder was designed by the cluster-plus-glue-atom (CPGA) model. The results reveal that with the increase of Bi content, the tensile strength of the alloy increased from 94.4 MPa to 131.3 MPa. Still, the elongation decreased, and the fracture mode changed from ductile to brittle, which was because the excessive hard and brittle Bi particles precipitated significantly reduce the ductility of solder. With increasing Bi content, the alloy wettability became better, and the spreading area increased from 52.92 mm2 to 59.09 mm2, which may be because the addition of Bi reduced the surface tension and melting point of the solder. Furthermore, the appropriate addition of Bi promoted the uniform and smooth growth of the intermetallic compound (IMC) layer at the Sn-Zn-Cu-Bi/Cu soldering interface, which was beneficial to improve the reliability of the soldering interface. Results demonstrate that Sn7.98Zn0.68Cu (wt.%) alloys with a Bi content of 2.2 wt.% exhibited better comprehensive properties. The findings have important implications for the development of a new Sn-Zn series low-temperature lead-free solder. [ABSTRACT FROM AUTHOR]

Inhomogeneous structures with carbon nanotubes (CNTs), reinforced with Cu composite foams as the reinforcing skeletons (CNTs/Cuf®Cu), have been designed to overcome the paradox between strength and ductility or conductivity in copper matrix composites. The interface between CNTs and the copper matrix is usually weak, due to poor wettability and interaction. In this study, nickel nanoparticles are decorated onto CNTs to improve interfacial bonding. The broader interface transition area between CNTs and copper with Ni3C interfacial products formed, and a combination of improved electrical conductivity (95.6% IACS), tensile strength (364.9 MPa), and elongation (40.6%) was achieved for the Ni-decorated CNTs/Cuf®Cu (Ni-CNTs/Cuf®Cu). In addition, the strengthening mechanisms are discussed in this study. [ABSTRACT FROM AUTHOR]

Transition‐metal alloys are currently drawing increasing attention as promising electrocatalysts for the alkaline hydrogen evolution reaction (HER). However, traditional density‐functional‐theory‐derived d‐band theory fails to describe the hydrogen adsorption energy (ΔGH) on hollow sites. Herein, by studying the ΔGH for a series of Ni−M (M=Ti, V, Cr, Mn, Fe, Co, Cu, Zn, Mo, W) bimetallic alloys, an improved d‐band center was provided and a potential NiCu electrocatalyst with a near‐optimal ΔGH was discovered. Moreover, oxygen atoms were introduced into Ni−M (O−NiM) to balance the adsorption/desorption of hydroxyl species. The tailored electrocatalytic sites for water dissociation can synergistically accelerate the multi‐step alkaline HER. The prepared O−NiCu shows the optimum HER activity with a low overpotential of 23 mV at 10 mA cm−2. This work not only broadens the applicability of d‐band theory, but also provides crucial understanding for designing efficient HER electrocatalysts. [ABSTRACT FROM AUTHOR]

Transition‐metal alloys are currently drawing increasing attention as promising electrocatalysts for the alkaline hydrogen evolution reaction (HER). However, traditional density‐functional‐theory‐derived d‐band theory fails to describe the hydrogen adsorption energy (ΔGH) on hollow sites. Herein, by studying the ΔGH for a series of Ni−M (M=Ti, V, Cr, Mn, Fe, Co, Cu, Zn, Mo, W) bimetallic alloys, an improved d‐band center was provided and a potential NiCu electrocatalyst with a near‐optimal ΔGH was discovered. Moreover, oxygen atoms were introduced into Ni−M (O−NiM) to balance the adsorption/desorption of hydroxyl species. The tailored electrocatalytic sites for water dissociation can synergistically accelerate the multi‐step alkaline HER. The prepared O−NiCu shows the optimum HER activity with a low overpotential of 23 mV at 10 mA cm−2. This work not only broadens the applicability of d‐band theory, but also provides crucial understanding for designing efficient HER electrocatalysts. [ABSTRACT FROM AUTHOR]

By means of first-principles calculations within the generalised gradient approximation (GGA), phase stability, elastic properties and electronic structures of B2 CoX(X = Ti, Zr and Hf) compounds as a function of pressure have been investigated. The formation energy indicates that CoTi is the most stable phase in these three B2 phases under different pressures. The elastic properties of B2 Co (X = Ti, Zr and Hf), calculated via the Voigt–Reuss–Hill (VRH) approximation, increase with increasing pressure. The mechanical anisotropies are characterised by the universal anisotropy index (AU) and the Zener anisotropy index (AZ). The sound velocities, Debye temperatures and melting temperature under applied pressure are also evaluated. Electronic structure show that the changes in the charge distribution are moderate under applied pressure, resulting in the general characteristics of the bonding betweenX(X = Ti, Zr and Hf) and Co remain unchanged. [ABSTRACT FROM PUBLISHER]

By using high purity aluminum powders and multi-walled carbon nanotubes (MWCNTs) as raw materials, MWCNTs/Al composites were fabricated with ball milling, followed by cold pressing, vacuum sintering, and hot extrusion. It was found that when the sintering temperature was 863 K, MWCNTs/Al composite sintered for 4 h showed good comprehensive properties, and its tensile strength and elongation reached to 156 MPa and 21%, respectively. The comprehensive mechanical properties of the composites became better with raising sintering temperature when the sintering time was 4 h. When the sintering temperature raised to 923 K, the tensile strength of the composite reached to 167 MPa which is three times more than that of annealed high purity aluminum, mainly due to the higher density and better interface bonding resulted from higher sintering temperature. CNTs' pulling out were observed obviously in the fractured surfaces, and load transfer may be the main strengthening mechanism. [ABSTRACT FROM PUBLISHER]

Cu and Cu–Al alloys with different stacking fault energies (SFEs) were processed using rolling and the Split Hopkinson pressure bar followed by rolling. The effect of strain rate on the microstructures and mechanical properties of the alloys were investigated using x-ray diffraction analyses, transmission electron microscopy, and tensile tests. Tensile testing results demonstrated that the strength and ductility of the samples increased simultaneously with decreasing SFE. Microstructural observations indicated that the average grain size of the samples decreased with decreasing SFE, but the twin and dislocation densities increased. With decreasing SFE, twinning becomes the dominant deformation mechanism. Our findings indicated that the SFEs significantly affect the strength and ductility of the materials because they play a key role in determining the deformation mechanism. Decreasing the SFE of Cu alloys has proved to be the optimum method to improve the ductility without compromising the strength of the material. [ABSTRACT FROM PUBLISHER]

The mechanical properties of solder alloys are a performance that cannot be ignored in the field of electronic packaging. In the present study, novel Sn-Zn solder alloys were designed by the cluster-plus-glue-atom (CPGA) model. The effect of copper (Cu) addition on the microstructure, tensile properties, wettability, interfacial characterization and melting behavior of the Sn-Zn-Cu solder alloys were investigated. The Sn29Zn4.6Cu0.4 solder alloy exhibited a fine microstructure, but the excessive substitution of the Cu atoms in the CPGA model resulted in extremely coarse intermetallic compound (IMC). The tensile tests revealed that with the increase in Cu content, the tensile strength of the solder alloy first increased and then slightly decreased, while its elongation increased slightly first and then decreased slightly. The tensile strength of the Sn29Zn4.6Cu0.4 solder alloy reached 95.3 MPa, which was 57% higher than the plain Sn-Zn solder alloy, which is attributed to the fine microstructure and second phase strengthening. The spreadability property analysis indicated that the wettability of the Sn-Zn-Cu solder alloys firstly increased and then decreased with the increase in Cu content. The spreading area of the Sn29Zn0.6Cu0.4 solder alloy was increased by 27.8% compared to that of the plain Sn-Zn solder due to Cu consuming excessive free state Zn. With the increase in Cu content, the thickness of the IMC layer decreased owing to Cu diminishing the diffusion force of Zn element to the interface. [ABSTRACT FROM AUTHOR]