Design of low-alloying and high-performance solid solution-strengthened copper alloys with element substitution for sustainable development

Solid solution-strengthened copper alloys have the advantages of a simple composition and manufacturing process,high mechanical and electrical comprehensive performances,and low cost;thus,they are widely used in high-speed rail contact wires,electronic component connectors,and other devices.Overcoming the contradiction between low alloying and high performance is an important challenge in the development of solid solution-strengthened copper alloys.Taking the typical solid solution-strengthened alloy Cu-4Zn-1Sn as the research object,we proposed using the element In to replace Zn and Sn to achieve low alloying in this work.Two new alloys,Cu-1.5Zn-1Sn-0.4In and Cu-1.5Zn-0.9Sn-0.6In,were designed and prepared.The total weight percentage content of alloying elements decreased by 43%and 41%,respectively,while the product of ultimate tensile strength(UTS)and electrical conductivity(EC)of the annealed state increased by 14%and 15%.After cold rolling with a 90%reduction,the UTS of the two new alloys reached 576 and 627MPa,respectively,the EC was 44.9%IACS and 42.0%IACS,and the product of UTS and EC(UTS×EC)was 97%and 99%higher than that of the annealed state alloy.The dislocations proliferated greatly in cold-rolled alloys,and the strengthening effects of dislocations reached 332 and 356 MPa,respectively,which is the main reason for the considerable improvement in mechanical properties.

Extending the solid solution range of sodium ferric pyrophosphate:Off‐stoichiometric Na_(3)Fe(2.5)(P_(2)O_(7))_(2)as a novel cathode for sodium‐ion batteries

Iron‐based pyrophosphates are attractive cathodes for sodium‐ion batteries due to their large framework,cost‐effectiveness,and high energy density.However,the understanding of the crystal structure is scarce and only a limited candidates have been reported so far.In this work,we found for the first time that a continuous solid solution,Na_(4−α)Fe_(2+α)_(2)(P_(2)O_(7))_(2)(0≤α≤1,could be obtained by mutual substitution of cations at center‐symmetric Na3 and Na4 sites while keeping the crystal building blocks of anionic P_(2)O_(7) unchanged.In particular,a novel off‐stoichiometric Na_(3)Fe(2.5)(P_(2)O_(7))_(2)is thus proposed,and its structure,energy storage mechanism,and electrochemical performance are extensively investigated to unveil the structure–function relationship.The as‐prepared off‐stoichiometric electrode delivers appealing performance with a reversible discharge capacity of 83 mAh g^(−1),a working voltage of 2.9 V(vs.Na^(+)/Na),the retention of 89.2%of the initial capacity after 500 cycles,and enhanced rate capability of 51 mAh g^(−1)at a current density of 1600 mA g^(−1).This research shows that sodium ferric pyrophosphate could form extended solid solution composition and promising phase is concealed in the range of Na_(4−α)Fe_(2+α)_(2)(P_(2)O_(7))_(2),offering more chances for exploration of new cathode materials for the construction of high‐performance SIBs.

Improvement effect of reversible solid solutions Mg_(2)Ni(Cu)/Mg_(2)Ni(Cu)H_(4)on hydrogen storage performance of MgH_(2)

The hydrogen absorption/desorption kinetic properties of MgH_(2)can be effectively enhanced by doping specific catalysts.In this work,MOFs-derived NiCu@C nanoparticles(~15 nm)with regular core-shell structure were successfully prepared and introduced into MgH_(2)(denoted as MgH_(2)-NiCu@C).The onset and peak temperatures of hydrogen desorption of MgH_(2)-11 wt.%NiCu@C are 175.0℃and282.2℃,respectively.The apparent activation energy of dehydrogenated reaction is 77.2±4.5 kJ/mol for MgH_(2)-11 wt.%NiCu@C,which is lower than half of that of the as-milled MgH_(2).Moreover,MgH_(2)-11 wt.%NiCu@C displays great cyclic stability.The strengthening"hydrogen pumping"effect of reversible solid solutions Mg_(2)Ni(Cu)/Mg_(2)Ni(Cu)H_(4)is proposed to explain the remarkable improvement in hydrogen absorption/desorption kinetic properties of MgH_(2).This work offers a novel perspective for the design of bimetallic nanoparticles and beyond for application in hydrogen storage and other energy related fields.

Effect of two-step solid solution on microstructure andδphase precipitation of Inconel 718 alloy

Inconel 718 is the most popular nickel-based superalloy and is extensively used in aerospace,automotive,and energy indus-tries owing to its extraordinary thermomechanical properties.The effects of different two-step solid solution treatments on microstructure andδphase precipitation of Inconel 718 alloy were studied,and the transformation mechanism fromγ″metastable phase toδphase was clarified.The precipitates were statistically analyzed by X-ray diffractometry.The results show that theδphase content firstly increased,and then decreased with the temperature of the second-step solid solution.The changes in microstructure andδphase were studied by scanning electron microscopy and transmission electron microscopy.An intragranularδphase formed in Inconel 718 alloy at the second-[100]_(δ)[011]γ step solid solution temperature of 925℃,and its orientation relationship withγmatrix was determined as//and(010)_(δ)//(111)γ.Furthermore,the Vickers hardness of different heat treatment samples was measured,and the sample treated by second-step solid solution at 1010℃ reached the maximum hardness of HV 446.84.

Ti_(3)AlC_(2−y)N_(y) carbonitride MAX phase solid solutions with tunable mechanical,thermal,and electrical properties

Changing the N content in the Ti_(3)AlC_(2−y)N_(y) MAX phase solid solutions allows for the fine-tuning of their properties.However,systematic studies on the synthesis and properties of Ti_(3)AlC_(2−y)N_(y) solid solution bulks have not been reported thus far.Here,previously reported Ti_(3)AlC_(2−y)N_(y) solid solution bulks(y=0.3,0.5,0.8,and 1.0)were synthesized via hot pressing of their powder counterparts under optimized conditions.The prepared Ti_(3)AlC_(2−y)N_(y) bulks are dense and have a fine microstructure with grain sizes of 6–8μm.The influence of the N content on the mechanical properties,electrical conductivities,and coefficients of thermal expansion(CTEs)of the prepared Ti_(3)AlC_(2−y)N_(y) bulk materials was clarified.The flexural strength and Vickers hardness values increased with increasing N content,suggesting that solid solution strengthening effectively improved the mechanical properties of Ti_(3)AlC_(2−y)N_(y).Ti_(3)AlCN(y=1)had the highest Vickers hardness and flexural strength among the studied samples,reaching 5.54 GPa and 550 MPa,respectively.However,the electrical conductivity and CTEs of the Ti_(3)AlC_(2−y)N_(y) solid solutions decreased with increasing N content,from 8.93×10^(−6) to 7.69×10^(−6) K^(−1) and from 1.33×10^(6) to 0.95×10^(6) S/m,respectively.This work demonstrated the tunable properties of Ti_(3)AlC_(2−y)N_(y) solid solutions with varying N contents and widened the MAX phase family for fundamental studies and applications.

Tungsten combustion in impact initiated W-Al composite based on W(Al) super-saturated solid solution

Element W can effectively improve the density of energetic structural materials. However, W is an inert element and does not combust in air. To change the reaction characteristics of W, 60 at.% Al was introduced into W through mechanical alloying. XRD analysis shows that after 50 h of ball milling, the diffraction peak of Al completely disappears and W(Al60) super-saturated solid solution powder is obtained. Further observation by HAADF and HRTEM reveals that the W(Al60) super-saturated solid solution powder is a mixture of solid solution and amorphous phase. Based on the good thermal stability of W(Al60) alloy powder below 1000℃, W(Al60)-Al composite was synthesized by hot pressing process.Impact initiation experiments suggest that the W(Al60)-Al composite has excellent reaction characteristics, and multiple types of tungsten oxides are detected in the reaction products, showing that the modified W is combustible in air. Due to the combustion of tungsten, the energy release rate of the W(Al60)-Al composite at speed of 1362 m/s reaches 2.71 kJ/g.

Quantifying Solid Solution Strengthening in Nickel-Based Superalloys via High-Throughput Experiment and Machine Learning

Solid solution strengthening(SSS)is one of the main contributions to the desired tensile properties of nickel-based superalloys for turbine blades and disks.The value of SSS can be calculated by using Fleischer’s and Labusch’s theories,while the model parameters are incorporated without fitting to experimental data of complex alloys.In thiswork,four diffusionmultiples consisting of multicomponent alloys and pure Niare prepared and characterized.The composition and microhardness of singleγphase regions in samples are used to quantify the SSS.Then,Fleischer’s and Labusch’s theories are examined based on high-throughput experiments,respectively.The fitted solid solution coefficients are obtained based on Labusch’s theory and experimental data,indicating higher accuracy.Furthermore,six machine learning algorithms are established,providing a more accurate prediction compared with traditional physical models and fitted physical models.The results show that the coupling of highthroughput experiments and machine learning has great potential in the field of performance prediction and alloy design.

Formation condition of solid solution type high-entropy alloy

Formation condition of high-entropy alloys with solid solution structure was investigated. Seventeen kinds of the high-entropy alloys with different components were prepared, the influencing factors （the comprehensive atomic radius difference δ, the mixing enthalpy AH and the mixing entropy AS） of phase composition of the alloys were calculated, and the microstructure and phase compositions of alloys were analyzed by using SEM and XRD. The result shows that only the systems with δ≤2.77 and △H≥-8.8 kJ/mol will form high entropy alloy with simple solid solution. Otherwise, intermetallic compounds will exist in the alloys. So, selection of the type of element has important effects on microstructure and properties of high entropy alloys.

Microstructure evolution of Mg-9Gd-2Er-0.4Zr alloy during solid solution treatment

Microstructure evolution of the cast Mg-9Gd-2Er-0.4Zr alloy during solid solution treatment at temperature of 460-520 ℃ for 3-12 h was investigated by using optical microscope（OM）,scanning electron microscope（SEM） and transmission electron microscope（TEM）.The results indicated that the grain size and the shape of second phase were obviously changed with time and/or temperature going on.At 460 ℃ for 3 h,the morphology of the Mg5（GdEr） phase was changed into fragmentized island morphology and the volume faction of the phase decreased.After solution solid treatment at 460 ℃ for 6 h,the Mg5（GdEr） phase was already completely dissolved,but some cuboid-shaped RE-rich phase precipitated.As the temperature increased,the morphology of the Mg5（GdEr） phase was transformed into the same morphology as that at 460 ℃ for 6 h.It was suggested that the microstructure evolution of the alloy during the solid solution treatment was concluded as follows：Mg5（GdEr） eutectic phase→Gd/Er atom diffusing into matrix→spheroidic Mg5（GdEr） phase→cuboid-shaped RE-rich phase→grain boundary immigration.

Microstructure and Properties of Cu-Cr-Zr Alloy after Rapidly Solidified Aging and Solid Solution Aging

The structure and properties of Cu-Cr-Zr alloy were studied after rapidly solidified aging and solid solution aging.At the early stage of aging （500℃ for 15 rain）, the hardness and the conductivity of the alloy rapidly solidified are 143 HV and 72% IACS, respectively. Under the same aging condition, the hardness and electrical conductivity of the alloy solid solution treated can reach 86 HV and 47% IACS, respectively. The microstructure was analyzed, and the grain size after rapid solidification is much smaller than that after solid solution treatment. By rapidly solidified aging the fine precipitates distribute inside the grains and along the grain boundary, while by solid solution aging there are large Cr particles along the grain boundary.

Highly efficient and selective photocatalytic dehydrogenation of benzyl alcohol for simultaneous hydrogen and benzaldehyde production over Ni-decorated Zn_(0.5)Cd_(0.5)S solid solution

Photocatalytic conversion of solar energy into hydrogen and high value-added fine chemicals has attracted increasing attention. Herein, we demonstrate an efficient photocatalytic system for simultaneous hydrogen evolution and benzaldehyde production by dehydrogenation of benzyl alcohol over Nidecorated Zn_(0.5)Cd_(0.5)S solid solution under visible light. The photocatalytic system shows an excellent hydrogen production rate of 666.3 μmol h^(-1) with high stability. The optimal apparent quantum yield of52.5% is obtained at 420 nm. This noble-metal-free photocatalytic system displays much higher activity than pure Zn_(0.5)Cd_(0.5)S and Pt-loaded Zn_(0.5)Cd_(0.5)S solid solution. Further studies reveal that the metallic Ni nanocrystals play an important role in accelerating the separation of photogenerated charge carriers and the subsequent cleavage of α-C–H bond during dehydrogenation of benzyl alcohol.

Structure, synthesis, and catalytic properties of nanosize cerium-zirconium-based solid solutions in environmental catalysis

Nanosize cerium-zirconium solid solution(CZO)with a special fluorite structure has received an increasing research interest due to their remarkable advantages such as excellent oxygen storage capacity and great flexibility in their composition and structure.By partial metal(including rare earth,transition,alkaline earth or other metal)doping into CZO,the physicochemical properties of these catalytic materials can be controllable adjusted for the study of specific reactions.To date,nanosize CZO has been prepared by co-precipitation,sol-gel,surfactant-assisted approach,solution combustion,micro-emulsion,high energy mechanical milling,etc.The advent of these methodologies has prompted researchers to construct well-defined networks with customized micromorphology and functionalities.In this review,we describe not only the basic structure and synthetic strategies of CZO,but also their relevant applications in environmental catalysis,such as the purification for CO,nitrogen oxides(NOx),volatile organic compounds(VOC),soot,hydrocarbon(HC),CO2 and solid particulate matters(PM),and some reaction mechanisms are also summarized.

Effect of doping elements on catalytic performance of CeO_2-ZrO_2 solid solutions

CeZr, CeYZr, LaCeZr, LaCePrZr, LaCePrYZr, and LaCePr solid solutions were prepared via the coprecipitation method, and characterized by means of X-Ray Diffraction （XRD） and Brunauer-Emmett-Teller （BET） techniques. The oxygen storage capacity （OSC） of the solid solutions was evaluated by the pulse technique and the catalytic activity was assessed using a 4-channel catalysis device. It was seen that the solid solutions presented cubic structure. The specific surface area and thermal stability could be enhanced by doping Y into the solid solutions. Doping a small amount of La had a positive effect on the thermal durability while doping a large amount of La decreased the specific surface area and the thermal stability. LaCePrZr and LaCePrYZr solid solutions synthesized using Baotou rare earth mineral residue enriched with LaCePr after Nd extraction presented a certain higher value in specific surface area and thermal stability, thereby enabling to be used as economic catalysts for automobile exhaust purification. Coating Al2O3 or SiO2 layer on the surface of ceria-zirconia solid solutions increased the specific surface area and thermal resistance.

Preparation and Characterization of CeO_2-ZrO_2 Solid Solution Ultrafine Particles Using Reversed Microemulsion

Ce0.6Zr0.4O2 solid solution ultrafine particle was prepared in the cyclohexane/water/OP-10/n-hexanol reversed microemulsion. The quasi-ternary phase diagram investigations showed that the system has narrow W/O type microemulison region, so it is the proper system to prepare Ce0.6Zr0.4O2 solid solution ultrafine particle. Some physical-chemical techniques such as TG/DTA, XRD, BET, and HRTEM are used to characterize the resultant powders. The results show that the fluorite cubic Ce0.6Zr0.4O2 solid solution is obtained at 400 ℃. The surface area is （146.7 m^2·g^-1）, which is higher than the surface area for sol-gel prepared sample （59.5m^2·g^-1）. HRTEM images indicated that the Ce0.6Zr0.4O2 solid solution ultrafine particle is well-crystallized, narrow size distribution, less agglomeration, within mean size of 5 -7 nm.

Synthesis and characterization of mesostructured ceria-zirconia solid solution

Mesostructured Ce0.6Zr0.4O2 solid solutions were synthesized by coprecipitation combined with evaporation-induced self-assembly process. The obtained materials were characterized by X-ray diffractometer （XRD）, Raman, transmission electron microscopy （TEM）, N2 sorption, and hydrogen temperature programmed reduction （H2-TPR）. The results showed that the solid solutions consisted of uniform nanocrystals, which piled homogeneous mesopores of about 4 nm. Furthermore, different surfactants had little influence on the mesoporous structures. All these samples exhibited high thermal stability.

SnO_2-based solid solutions for CH_4 deep oxidation: Quantifying the lattice capacity of SnO_2 using an X-ray diffraction extrapolation method

A series of SnO2‐based catalysts modified by Mn, Zr, Ti and Pb oxides with a Sn/M （M=Mn, Zr, Ti and Pb） molar ratio of 9/1 were prepared by a co‐precipitation method and used for CH4 and CO oxidation. The Mn3＋, Zr4＋, Ti4＋and Pb4＋cations are incorporated into the lattice of tetragonal rutile SnO2 to form a solid solution structure. As a consequence, the surface area and thermal stability of the catalysts are improved. Moreover, the oxygen species of the modified catalysts become easier to be reduced. Therefore, the oxidation activity over the catalysts was improved, except for the one modified by Pb oxide. Manganese oxide demonstrates the best promotional effects for SnO2. Using an X‐ray diffraction extrapolation method, the lattice capacity of SnO2 for Mn2O3 was 0.135 g Mn2O3/g SnO2, which indicates that to form stable solid solution, only 21%Sn4＋cations in the lattice can be maximally replaced by Mn3＋. If the amount of Mn3＋cations is over the capacity, Mn2O3 will be formed, which is not favorable for the activity of the catalysts. The Sn rich samples with only Sn‐Mn solid solution phase show higher activity than the ones with excess Mn2O3 species.

Surface and Texture Properties of Tb-Doped Ceria-Zirconia Solid Solution Prepared by Sol-Gel Method

The three-way catalysts （TWCs） promoters Ce0.6Zr0.4- x TbxO2-y were prepared by sol-gel method. BET surface areas analysis indicated that an increase of the dopant Tb content from x = 0.05 to x = 0.15 favors an increase of surface area from 66.8 to 80.4 m^2· g^-1 compared with the undoped sample Ce0 .6oZr0.40O2 65.1 m^2·g^- 1 after calcination at 650℃. Transmission electron microscopy （TEM） observation indicated that the doped samples have a higher thermal stability. The XRD and Raman spectra confirmed that the Ce0.6Zr0.4-xTbxO2-y cubic solid solution is formed. XPS analysis revealed that Ce and Tb mainly existed in the form of Ce^4＋ and Tb^3 ＋ , and Zr existed in the form of Zr^4＋ on the surface of the samples. The doped samples were homogenous in composition ; the introduction of Tb into the CeO2-ZrO2 promoters resuited in the formation of a solid solution, and the concentration of surface lattice oxygen was increased.

Researches on the Structure and Properties of Mullite Solid Solution Made from Industrial Waste

The waste slag from aluminum profile factory and silicon fine powder from ferroalloy factory were utilized as the main raw materials to synthesize mullite solid solution Al4＋2xSi2-xO10-x/2, whose defect formation mechanism, crystalline phase composition, crystal cell parameters, microstructures and morphologies were characterized in detail by XRD and SEM. The results show that because of the ultrafine particle size of the materials, the content of mullite solid solution synthesized by this method is higher than that by regular method. Keywords： waste slag from aluminum factory, silicon fine powder, mullite, solid solution

Effects of single and multi-stage solid solution treatments on microstructure and properties of as-extruded AA7055 helical profile

The effects of single-stage solution treatment(SST),enhanced solution treatment(EST),high-temperature pre-precipitation(HTPP)and multi-stage solution treatment(MST)on the microstructure,mechanical properties and corrosion resistance of the as-extruded 7055 aluminium alloy(AA7055)helical profile were investigated using differential scanning calorimetry(DSC),optical microscopy(OM),scanning electron microscopy(SEM),electron back-scattered diffraction(EBSD)and transmission electron microscopy(TEM).It was observed that EST and MST could promote the dissolution of the second-phase particles compared with the traditional SST,and the intergranular phases were distinctly discontinuously distributed after HTPP and MST.There was obvious difference in the main texture type and texture strength for the alloy after different solid solution treatments.HTPP could improve the corrosion resistance of the alloy by regulating the intergranular phases,but the mechanical properties were severely weakened.While the good corrosion resistance of the alloy could be obtained by MST without obvious strength loss.As a result,the MST is an ideal solid solution treatment scheme for AA7055.

Copper-ceria solid solution with improved catalytic activity for hydrogenation of CO to CHOH

A copper-ceria solid solution and ceria-supported copper catalysts were prepared and used for the catalytic hydrogenation of CO2 to CH3OH.According to site-specific classification and quantitative analyses(X-ray diffraction,Raman spectroscopy,X-ray photoelectron spectroscopy,H2 temperature-programmed reduction,and CO adsorption),the interfaces of the prepared catalysts were classified as Cu incorporated into ceria(Cu-Ov-Cex),dispersed Cu O(D-Cu O-Ce O2),and bulk Cu O(B-Cu O-Ce O2)over the Ce O2 surface.These results,together with those of activity tests,showed that the Cu-Ov-Cex species was closely related to the CO2 hydrogenation activity and resulted in a much higher turnover frequency of CH3OH production than that observed with the D-Cu O-Ce O2 and B-Cu O-Ce O2 species.Thus,the copper-ceria solid solution exhibited improved activity due to the higher Cu-Ov-Cex fraction.