Effect of ageing process on microstructure, corrosion behaviors and mechanical properties of Al-5.6Zn-1.6Mg-0.05Zr alloy

The influence of different ageing processes on the microstructure, corrosion behaviors and mechanical properties of extruded Al-5.6Zn-1.6Mg-0.05Zr(wt.%) alloy was studied in this work. The changes of morphology, size and distribution of MgZn_(2)precipitate with ageing temperature and time were revealed by optical and electron microscopy. Intergranular corrosion(IGC) and exfoliation corrosion(EXCO) tests were carried out to assess the changes in corrosion susceptibility of the tempered alloy, and some white spots on the surface of the sample aged for longer time were found to be precursors of pits. Electrochemical cyclic polarization test depicted the corrosion behavior under different tempers. Ageing influences on the mechanical behaviors of the alloy were revealed by evaluating its microhardness and tensile strength. The microscopic features of the strengthening phases determined by the ageing procedure directly affect the corrosion resistance and mechanical properties of the alloy.

Mitigating the negative catalytic effect of CuO by FAS-17 coated Al nanopowder:Isothermal ageing of Al/CuO nanothermite at 71°C and 60%relative humidity

The safety and reliability of weapon systems would be significantly affected by changes in the performance of energetic materials due to ambient temperature and humidity.Nanothermites have promising applications due to their excellent reactivity.Therefore it becomes extremely important to understand their aging and failure process in the environment before using them.Here,the aging and failure process of Al/CuO in 71°C/60%RH were investigated,and showed that CuO nanoparticles negatively catalyze Al nanopowders,resulting in rapid hydration.The anti-aging effect of FAS-17-coated Al nanopowder was also examined.The aging process of Al,Al/CuO,and Al@FAS-17/CuO in high humidity and heat environment were revealed by quasi-in situ SEM and TEM methods.Compared with the aging of pure Al,the Al nanopowder in the nanothermites strongly agglomerated with the CuO nanopowder and hydrated earlier.This may be caused by CuO catalyzed hydration of Al nanopowder.The energy release experiments showed that the performance of Al/CuO decreased rapidly and failed to ignite after 4 h of aging.In contrast,the Al@FAS-17/CuO thermite can achieve long-term stability of up to 60 h in the same environment by simple cladding of FAS-17.It is found that FAS-17 coated Al nanopowder can prevent both particle agglomeration and water erosion,which is an effective means to make nanothermites application in high humidity and heat environment.

Microstructure and Mechanical Properties of Al-11.3Zn-3.2Mg-1.3Cu-0.2Zr-0.1Sr-x Ti Extruded Aluminum Alloy with Different Aging Process

The influences of adding different amount of Ti(0%,0.39%,0.87%)and three kinds of difierent aging processes(T6,T6I6,RRA)on the microstructure and properties of Al-11.3Zn-3.2Mg-1.3Cu-0.2Zr-0.1Sr were investigated.Results show that an appropriate amount of Ti can effectively inhibit grain growth and thus achieve the efiect of grain refinement.The contribution of dislocation density and dislocation strengthening become the biggest when Ti content is 0.39%.At the same time,the intergranular corrosion depth is the lowest when Ti content is 0.39%.Among the three aging processes,the alloys reach the greatest hardness and tensile strength in T6I6.The biggest tensile strength reaches 716.77 MPa.However,when aging at RRA,the alloys obtain the greatest elongation,reaching 7.2%,as well as the good corrosion resistance.

Quantitative Changes in Main Parameters of Secondary Xylem during Aging Process in Pinus bugeana

Quantitative changes in main parameters of secondary xylem during aging process were studied in four trees of Pinus bungeana collected from two different sites.No marked difference was found in the width of heartwood, transition zone and sapwood at four cardinal directions and a wider sapwood and a narrower heartwood were noted in fast grown trees than in slowly grown ones. Earlywood generally showed a higher percentage of aspirated pits than latewood regardless of the age and growth conditions of the trees in addition , the earliest dead cells and the last living cells in the marginal cells were found a bit earlier than those in the central cells. It thus seems appropriate to conclude that the death of cells results largely from decrease of fluid permeability as the number of aspirated pits increases during aging process.

Kinetic Process and Conductivity of Ag^+ Ion Exchange for Polycrystalline Na-β"-Al_2O_3

This paper reports the kinetic process of Ag ion exchange for the polycrystalline Na-β'-Al2O3.The interdiffusion coefficients in the process of Ag+ and Na+ ion exchange have been calculated with an 'one dimensional double side diffusion model'. Microstructures of the samples were observed and analysed by XRD, EMPA, SEM. The results of the conductivity measurements for samples with Na+, Ag+ and Na+-Ag+ mobile ions are presented and explained

Optimizing temperature coefficient of Sm_(2)Co_(17)-type magnets through adjusting the isothermal aging process

The high-temperature magnetic perfo rmance and micro structure of Sm_(1-x)Gd_(x)(Co_(bal)Fe_(0.09)Cu_(0.09)Zr_(0.025))_(7.2)(x=0.3,0.5) magnets were investigated.With the isothermal aging time decreasing from 11 to 3 h,the temperature coefficient of intrinsic coercivity in the temperature range of 25-500℃,β_(25-500℃),was optimized from -0,167%/℃ to-0.112%/℃ for x=0.3 magnets.The noticeable enhancement(~33%) of temperature stability is correlated with the increased content of 1:5H cell boundary phase and its relatively high Curie temperature as well.However,for the x=0.5 magnet,it is found that the presence of Sm_(5)Co_(19) phases and wider nanotwin variants hinder the formation of 1:5H cell boundary phase.The insufficient 1:5H is not beneficial to the proper redistribution of Cu in cell boundary,making the x=0.5 magnet difficult to achieve higher temperature stability.Consequently,the approach of adjusting the isothermal aging process can offer guidance for attaining superior magnetic performance in the temperature range from 25 to 500℃ for Gd-substituted Sm_(2)Co_(17)-type magnets.

Ag Deposition Forms and Uniformity on Porous Silicon by Electrochemical Method

The electrochemical deposition technique was applied to achieve porous silicon （PS） surface passivated with Ag deposition for improving the properties of PS photoluminescence. The relation of Ag depositing forms to current density and the effect of PS hydrophilic surface on deposition uniformity were investigated. The experimental results indicated that there were two critical current densities （maximum and minimum） in which Ag was absent and electroplated on PS surface correspondingly, and the range of current density for deposition of Ag on porous silicon was from 50 μA/cm^2 to 400 μA/cm^2. The process of changing PS surface from hydrophobic into hydrophilic had positive effect on Ag deposition uniformity. Under the same experimental conditions, PS hydrophobic surface presented uneven Ag deposition.However, hydrophilic surface treated with SC-1 solution was even. Finally, the effect of PS surface passivation with Ag even deposition on photoluminescence intensity and stabilization of PS was studied. It was discovered that Ag passivation inhibited the degradation of PL intensity effectively. In addition, excessive Ag deposition had a quenching effect on room-temperature visible photoluminescence of PS.

Detrended cross-correlation analysis of electroencephalogram

In the paper we use detrended cross-correlation analysis （DCCA） to study the electroencephalograms of healthy young subjects and healthy old subjects. It is found that the cross-correlation between different leads of a healthy young subject is larger than that of a healthy old subject. It was shown that the cross-correlation relationship decreases with the aging process and the phenomenon can help to diagnose whether the subject＇s brain function is healthy or not.

Microstructure and Performance Analysis of Organic Coating under High Temperature and High CO_2 Partial Pressure

To evaluate the property of the organic coatings in oil and gas plants, the aging process was studied in high temperature and high CO_2 partial pressure environment. Correlations were developed between the macroscopic properties and microstructure of the organic coatings. The surface appearance, mechanical properties, and permeability of the organic coatings were measured. Furthermore, the crystal structure of the organic coatings was investigated through synchrotron radiation grazing incidence X-ray diffraction（GIXRD） on the BL14B1 beam line in Shanghai Synchrotron Radiation Facility. Combined with the Fourier transform infrared spectroscopy, the molecular structure of the organic coatings was investigated. The experimental results indicate that the thickness variation and weight loss of the organic coatings increase with the immersion time, and the penetration resistance of the coating obviously decreases as the temperature rises. Moreover, the degradation of the organic coatings with immersion time in high temperature and high CO_2 partial pressure environment is caused by the amorphization of the organic coatings as the groups and bonds of the organic coatings were not damaged.

Insights into influence of aging processes on zero-valent iron modified biochar in copper(II) immobilization: from batch solution to pilot-scale investigation

The zero-valent iron modified biochar materials are widely employed for heavy metals immobilization.However,these materials would be inevitably aged by natural forces after entering into the environment,while there are seldom studies reported the aging effects of zero-valent iron modified biochar.In this work,the hydrogen peroxide and hydrochloric acid solution were applied to simulate aging conditions of zero-valent iron modified biochar.According to the results,the adsorption capacity of copper(II)contaminants on biochar,zero-valent iron modified biochar-1,and zero-valent iron modified biochar-2 after aging was decreased by 15.36%,22.65%and 23.26%,respectively.The surface interactions were assigned with chemisorption occurred on multi-molecular layers,which were proved by the pseudo-second-order and Langmuir models.After aging,the decreasing of capacity could be mainly attributed to the inhibition of ion-exchange and zero-valent iron oxidation.Moreover,the plant growth and soil leaching experiments also proved the effects of aging treatment,the zero-valent iron modified biochar reduced the inhibition of copper(II)bioavailability and increased the mobility of copper(II)after aging.All these results bridged the gaps between bio-adsorbents customization and their environmental behaviors during practical agro-industrial application.

Microplastics’Aging Processes in the Aquatic Environment:Aging Mechanisms,Altered Environmental Behaviors and Ecotoxicity

Microplastics(MPs)have been one of the most concerned environmental issues since the 21st century.MPs are plastic particles with diameters less than 5 mm,which are widely sourced in the aquatic environment.After being released into the aquatic environment,MPs would experience complicated physical,chemical and biological aging processes driven by mechanical forces,photooxidation,and biological degradation,which would result in changes in MPs’physicochemical properties,such as the particle size,specific surface area,hydrophobicity,crystallinity,etc.In this review,we have illustrated the current study status on MPs’environmental aging processes and pointed out the knowledge gaps.MPs’aging processes would consequentially influence MPs’interaction with the co-existing organic and inorganic pollutants in the aquatic environment as well as lead to the leaching of chemical additives involved in plastic production,including plasticizers and flame retardants,which can trigger high ecotoxicity to the aquatic environment.Furthermore,aged MPs would cause ecotoxicity to aquatic organisms via bioaccumulation,biomagnification,and indirect carrier pathways.The review would provide an in-depth overview of MPs’environmental aging processes and consequential ecotoxicity implications,as well as propose future research needs.

Effect of Different Aging Processes on the Microstructure and Mechanical Properties of a Novel Al–Cu–Li Alloy

The effects of different aging processes on the microstructure and mechanical properties of a novel Al-Cu-Li alloy have been investigated by X-ray diffraction, scanning electron microscopy and transmission electron microscopy. It is found that the tensile properties of a novel Al-Cu-Li alloy are sensitive to aging processes, which correspond to different microstructures. σ（Al_5Cu_6Mg_2） and T_1（Al_2CuLi） phases are the major precipitates for the alloy in T6 aging condition（165 ℃/60 h）. After duplex aging condition（150 ℃/24 h ＋ 180 ℃/12 h）, σ, θ＇（Al_2Cu） and T_1 phases are detected. Only the T_1 phases can be found in the T8 state alloy（6% pre-strain＋135 ℃/60 h）. The failure modes of alloy in T6 and duplex aging conditions are dimple-intergranular fracture, while typical quasi-cleavage fracture in T8 condition.

Effects of aging process on adsorption–desorption and bioavailability of fomesafen in an agricultural soil amended with rice hull biochar

Biochar has been introduced as an acceptable soil amendment due to its environmental benefits such as sequestering soil contaminants. However, the aging process in biochar amended soil probably decreases the adsorption capacity of biochar through changing its physico-chemical properties. Adsorption, leaching and bioavailability of fomesafen to corn in a Chinese soil amended by rice hull biochar after 0, 30, 90 and 180 days were investigated. Results showed that the addition of 0.5%-2% fresh biochar significantly increases the adsorption of fomesafen 4-26 times compare to unamended soil due to higher SSA of biochar. Biochar amendment also decreases fomesafen concentration in soil pore water by 5%-23% resulting lower risk of the herbicide for cultivated plants. However, the aging process decreased the adsorption capacity ofbiochar since the adsorption coefficient values which was 1.9-12.4 in 0.5%-2% fresh biochar amended soil, declined to 1.36-4.16, 1.13-2.78 and 0.95-2.31 in 1, 3 and 6-month aged treatments, respectively. Consequently, higher desorption, leaching and bioavailable fraction of fomesafen belonged to 6-month aged treatment. Nevertheless, rice hull biochar was effective for sequestering fomesafen as the adsorption capacity of biochar amended soil after 6 months of aging was still 2.5-5 times hi^her compared to that of unamended soil.

Influence of Fe-rich phases and precipitates on the mechanical behaviour of Al-Cu-Mn-Fe-Sc-Zr alloys studied by synchrotron X-ray and neutron

A multiscale methodology using scanning and transmission electron microscope,synchrotron X-ray nano-tomography and micro-tomography,small angle neutron scattering,and in situ synchrotron X-ray diffrac-tion has been used,to reveal the effect of Fe-rich phases and precipitates on the mechanical behaviour of an Al-Cu-Mn-Fe-Sc-Zr alloy.Theα-Al grains size is reduced from 185.1μm(0 MPa)and 114.3μm(75 MPa)by applied pressure.Moreover,it has been demonstrated that suitable heat treatments modify the 3D morphology of Fe-rich phases from interconnected to a disaggregated structure that improves the mechanical properties of the alloy.The size and morphology evolution of fine precipitates under differ-ent ageing temperature and time are revealed.At ageing temperature of 160℃,the precipitates change from GP zones toθ’(around 75 nm in length)with ageing time increasing from 1 h to 24 h;the Vick-ers hardness increases from 72.0 HV to 110.7HV.The high ductility of the Sc,Zr modified Al-Cu alloy is related to the complex shape and the loss of interconnectivity of the Fe-rich particles due to the heat treatment.The evolution of the crystal lattice strains inα-Al,andβ-Fe calculated during tensile test us-ing in-situ synchrotron X-ray diffraction corroborates the influence of the microstructure in the ductility of the modified alloy.

The precipitation behaviours and strengthening mechanism of a Cu-0.4 wt% Sc alloy

The precipitation behaviours during the aging process and the corresponding strengthening mechanism of a Cu-0.4 wt%Sc alloy were systematically investigated in this study.The phase transformation sequence of the precipitation in the aging process of the Cu-0.4 wt%Sc alloy was found to be:supersaturated solid solution→Sc-enriched atomic clusters→metastable phase→Cu4Sc phase.The tetragonal structured lamellar Cu4Sc precipitates,with a habit plane parallel to the{111}plane of the Cu matrix and orientation relationships of(022)_(α)//(211)_(Cu4Sc)and[011]_(α)//[113]_(Cu4Sc),are found homogeneously distributed in the matrix.A combined process of cryogenic rolling(CR)and aging was designed for optimization of the mechanical and electrical properties.Excellent integration of yield strength(696 MPa)and electrical conductivity(62.8%IACS)of this alloy was achieved by cryogenic rolling and subsequent aging process at 400℃for 4 h.The significant precipitation strengthening effect of this alloy is attributed to the Cu4Sc precipitates with an extremely small size of only 1.5–3 nm.The leading strengthening mechanism is considered as the superposition of both coherent strengthening and Orowan strengthening effects.

Online single particle analysis of chemical composition and mixing state of crop straw burning particles： from laboratory study to field measurement

Fresh straw burning （SB） particles were generated in the laboratory by the combustion of rice straw and corn straw. The chemical composition and mixing state of the fresh SB particles were investigated by an Aerosol Time-of-Flight Mass Spectrometer （ATOFMS）. Based on the mass spectral patterns, the SB particles were clustered into four major types： Salt, Organic Carbon （OC）, Elemental Carbon （EC）, and internally mixed particles of EC and OC （EC-OC）. In addition, particles containing ash, polycyclic aromatic hydrocarbons, heavy metals or nicotine were also observed. Physical and chemical changes of the SB particles immediately after the emission were analyzed with highly time-resolved data. During the aging processes, the average particle size increased steadily. Freshly emitted organic compounds were gradu- ally oxidized to more oxygenated compounds in the OC- containing particles. Meanwhile, an important displace- ment reaction （2KCI＋ SO24- KzSO4 ＋ 2C1-） was observed. The marker ions for SB particles were optimized and applied to identify the SB particles in the ambient atmosphere. The fluctuation of the number fraction of ambient SB particles sorted by ATOFMS agrees well with that of water soluble K＋ measured by an online ion chromatography, demonstrating that the optimized marker ions could be good tracers for SB particles in field measurements.

Correlation between T lymphocyte subsets in peripheral blood lymphocytes and 2-year all-cause mortality in an apparently healthy elderly Chinese cohort

Background Few data have been acquired on the predictive value of age-related T-lymphocyte subsets among older individuals. The present study has determined the distribution of T-cell phenotypes and their correlation to 2-year mortality in a cohort of Chinese male seniors. Methods A total of 101 asymptomatic elderly individuals with laboratory homeostasis were enrolled at baseline. Three age subgroups were categorized as young （65-74 years old）, middle （75-84 years old ）, and old （≥85 years） for age-related comparison. T-cell subsets in peripheral blood were measured by multi-colored flow cytometry. Results At baseline, there was a mild negative correlation by age for total lymphocytes and CD3^＋ T-cells. The frequency of CD28 and CD95 demonstrated a ＂curved＂ rather than linear tendency by age. At 2-year follow-up, little change of T-cell distribution was found among those who remained alive （as survivors） comparing the data at baseline to the 2-year time point. Immune risk phenotypes were distinctly demonstrated between survivors and non-survivors. Conclusions Since few studies have studied on the distribution of T-lymphocyte subsets in an elderly Chinese population, our results have not only provided reference values of T-subsets for aged Chinese men, but confirmed the immune risk phenotypes among elderly Chinese. The inappropriate age-dependent trajectory of CD28^-/CD8^＋ and CD95^-/CD8^＋ by age, which suggested 85 might be an inflexion point of age during T-cell ageing, warrants further exploration of the underlying mechanisms of T-cell ageing.

Microstructure and properties of aging Cu–Cr–Zr alloy

The crystallography and morphology of precipitate particles in a Cu matrix were studied using an aged Cu–Cr–Zr alloy by transmission electron microscopy（TEM） and high-resolution transmission electron microscopy（HRTEM）. The tensile strength and electrical conductivity of this alloy after various aging processes were tested. The results show that two kinds of crystallographic structure associated with chromium-rich phases, fcc and bcc structure, exist in the peak-aging of the alloy. The orientation relationship between bcc Cr precipitate and the matrix exhibits Nishiyama–Wasserman orientation relationship. Two kinds of Zr-rich phases（Cu4Zr and Cu5Zr）can be identified and the habit plane is parallel to {111}Cu plane during the aging. The increase in strength is ascribed to the precipitation of Cr- and Zr-rich phase.

Enhanced mixing state of black carbon with nitrate in single particles during haze periods in Zhengzhou, China

Black carbon(BC)plays an important role in air quality and climate change,which is closely associated with its mixing state and chemical compositions.In this work the mixing state of BC-containing single particles was investigated to explore the evolution process of ambient BC particles using a single particle aerosol mass spectrometer(SPAMS)in March 2018 in Zhengzhou,China.The BC-containing particles accounted for 61.4%of total detected ambient single particles and were classified into five types including BC-nitrate(BC-N,52.3%)as the most abundant species,followed by BC-nitrate-sulfate(BC-NS,22.4%),BCOC(16.8%),BC-fresh(BC-F,4.5%)and BC-sulfate particles(BC-S,4.0%).With enhancement of the ambient nitrate concentration,the relative peak area(RPA)of nitrate in BC-N and BC–NS particles both increased,yet only the number fraction(N_(f))of BC–N particles increased while the N_(f) of BC-NS particles decreased,suggesting that the enhanced mixing state of BC with nitrate was mainly due to the increase in the ambient nitrate mass concentration.In addition,the Nfof BC-N decreased from 65.3%to 28.4%as the absorbing Angstrom exponents(AAE)of e BC increased from 0.75 to 1.45,which indicated the reduction of light absorption ability of aged BC particles with the enhanced formation of BC-N particles.The results of this work indicated a change in the mixing state of BC particles due to the dominance of nitrate in PM_(2.5),which also influenced the optical properties of aged BC particles.