Corrosion behavior of 2A97 Al-Cu-Li alloys in different thermomechanical conditions by quasi-in-situ analysis

As a promising material in the aircraft industry,2A97 Al-Cu-Li alloy exhibits high corrosion susceptibility that may limit its application.In the present work,to illustrate the influences of precipitate and grain-stored energy on localized corrosion evolution in 2A97 Al-Cu-Li alloy,cold working and artificial aging were carried out to produce 2A97 Al-Cu-Li alloys under different thermomechanical conditions.Quasi-in-situ analysis,traditional immersion test and electrochemical measurement were then conducted to examine the corrosion behavior of 2A97 alloys.It is revealed that precipitate significantly affects Cu enrichment at corrosion fronts,which determines corrosion susceptibility of alloys,whereas grain-stored energy distribution is closely associated with localized corrosion propagation.It is also indicated that quasi-in-situ analysis exhibits a consistent corrosion evolution with traditional immersion tests,which is regarded as a proper method to explore localized corrosion mechanisms by providing local microstructural information with enhanced time and spatial resolutions.

In situ analysis of multi-twin morphology and growth using synchrotron polychromatic X-ray microdiffraction

Synchrotron polychromatic X-ray microdiffraction（micro-XRD） was applied to study in situ deformation twinning of commercially AZ31（Mg-3Al-1Zn） strip subjected to uniaxial tension.The morphology and growth of twins were analyzed in situ under the load level from 64 to 73 MPa.The X-ray microdiffraction data,collected on beamline 12.3.2 at the Advanced Light Source,were then used to map an area of 396μm x 200μm within the region of interest.The experimental set-up and X-ray diffraction microscopy with a depth resolution allow the position and orientation of each illuminated grain to be determined at the submicron size.A list of parent grains sorted by crystallographic orientation were selected to examine their twinning behavior.The results depict twin variant selection,local misorientation fluctuation and mosaic spread for multi-twins within the same parent grain.As load increases,the amplitude of misorientation fluctuation along twin trace keeps increasing.This is attributable to the accumulation of geometrically necessary dislocations.

Modern applications of scanning electrochemical microscopy in the analysis of electrocatalytic surface reactions

Development of reaction-tailored electrocatalysts is becoming increasingly important as energy and environment are among key issues governing our sustainable future.Electrocatalysts are inherently optimized for application towards reactions of interest in renewable energy,such as those involved in water splitting and artificial photosynthesis,owing to its energy efficiency,simple fabrication,and ease of operation.In this view,it is important to secure logical design principles for the synthesis of electrocatalysts for various reactions of interest,and also understand their catalytic mechanisms in the respective reactions for improvements in further iterations.In this review,we introduce several key methods of scanning electrochemical microscopy(SECM)in its applications towards electrocatalysis.A brief history and a handful of seminal works in the SECM field is introduced in advancing the synthetic designs of electrocatalysts and elucidation of the operating mechanism.New developments in nano-sizing of the electrodes in attempts for improved spatial resolution of SECM is also introduced,and the application of nanoelectrodes towards the investigation of formerly inaccessible single catalytic entities is shared.

In situ LA-ICP-MS analyses of mica and wolframite from the Maoping tungsten deposit,southern Jiangxi,China

The Maoping tungsten deposit is located in the Nanling W-Sn metallogenic belt in South China.Greisen and quartz vein types of mineralization developed in this deposit.Protolithionite occurs in the granite.Zinnwaldite is occurs mainly in greisen and wolframite-quartz veins whereas phengite is found in the underground quartz veinlets.In granite and greisen,protolithionite,and zinnwaldite are partly replaced by Li-phengite.LA-ICP-MS trace element analyses of micas and wolframite are employed to characterize the ore-forming source and evolution of ore forming fluids.Micas show compositional variation trend in vertical directions with a decrease of W,Sn,Nb,and Ta and an increase of MgO,V,Ni,and Co.Wolframite in greisen has higher Mo,Sn,Nb,Ta,and REEs than those in quartz veins.All wolframites show similar REE patterns with enrichment of HREE.Wolframites in greisen and quartz veins have negative Eu anomalies,while wolframites in quartz veinlet display positive Eu anomalies.Compositions of mica and wolframite from different mining levels of the Maoping deposit suggest that the ore-forming fluids are dominated by magmatic hydrothermal fluids in the deep with a slight addition of meteoric water in the shallow.Brittle fractureinduced depressurization and fluid mixing controlled the evolution of ore-forming fluids and possibly lead to the wolframite deposition.

EFFECT OF Ti-ADDITION ON MECHANICAL ALLOYING OF NiAl

Mechanical alloying (MA) of Ni50Al45Ti5 (atomic per cent) is studied by in situ thermal analyses, XRD and metallography. The results showed that the alloying process of Ni50Al45Ti5 is similar to that of Ni50Al50. The addition of 5 at.%Ti prolongs the milling time of alloy prior to the explosive reaction in the alloy. The final product is nanocrystalline β-phase NiAl(Ti) (B2 structure). The addition of 5 at.% Ti shows little effect on the lattice parameter of β-phase.

Assessment and adjustment of sea surface salinity products from Aquarius in the southeast Indian Ocean based on in situ measurement and My Ocean modeled data

The in situ sea surface salinity（SSS） measurements from a scientific cruise to the western zone of the southeast Indian Ocean covering 30°-60°S, 80°-120°E are used to assess the SSS retrieved from Aquarius（Aquarius SSS）.Wind speed and sea surface temperature（SST） affect the SSS estimates based on passive microwave radiation within the mid- to low-latitude southeast Indian Ocean. The relationships among the in situ, Aquarius SSS and wind-SST corrections are used to adjust the Aquarius SSS. The adjusted Aquarius SSS are compared with the SSS data from My Ocean model. Results show that：（1） Before adjustment： compared with My Ocean SSS, the Aquarius SSS in most of the sea areas is higher; but lower in the low-temperature sea areas located at the south of 55°S and west of 98°E. The Aquarius SSS is generally higher by 0.42 on average for the southeast Indian Ocean.（2） After adjustment： the adjustment greatly counteracts the impact of high wind speeds and improves the overall accuracy of the retrieved salinity（the mean absolute error of the Zonal mean is improved by 0.06, and the mean error is-0.05 compared with My Ocean SSS）. Near the latitude 42°S, the adjusted SSS is well consistent with the My Ocean and the difference is approximately 0.004.

In situ Analysis of Major Elements, Trace Elements and Sr Isotopic Compositions of Apatite from the Granite in the Chengchao Skarn-Type Fe Deposit, Edong Ore District： Implications for Petrogenesis and Mineralization

Major elements, trace elements and Sr isotopic compositions of apatite from the granite in the Chengchao skarn-type Fe deposit of Edong ore district of Middle-Lower Yangtze River metallogenic belt were measured using EMPA （electron microprobe）, LA-ICP-MS （laser ablation inductively coupled plasma mass spectrometer） and LA-MC （multicollector）-ICP-MS methods in order to reveal the petroge- netic and metallogenic significance of the skarn-type iron deposits. The results show that the apatite in Chengchao granite is fluorapatite, which displays slight variation in major elements. The REE distribution pattern of the apatite is similar to that of the whole rocks, with strong negative Eu anomaly and low Sr/Y ratio. The concentration of Mn in apatite is low （140 ppm-591 ppm） and the Sr isotopic composition shows a limited variation from 0.706 9 to 0.708 2. The high oxygen fugacity of the Chengchao granite, implied by the low Mn content in apatite, is possibly attributed to contamination of the gypsum from sedimentary rock strata, which has long been thought to be an important factor that controls the Fe mineralization in the Middle-Lower Yangtze River metallogenic bell This study also proves that the Eu/Eu＊ value and Sr/Y ra- tio in apatite can be effectively used to identify the adakitie affinity. The in situ Sr isotope analysis of apatite is in consistent with the bulk rock analysis, which indicates that the apatite Sr isotope can represent the ini- tial Sr isotopic compositions of the magma. The Sr isotope and negative Eu anomaly in apatite imply that the Chengchao granite is likely sourced from crust-mantle mixed materials.

In Situ Analysis for Herbal Pieces of Aconitum Plants by Using Direct Analysis in Real Time Mass Spectrometry

In this study,an extend application was developed to in situ analyze the herbal pieces of Aconitum plants by Direct Analysis in Real Time Mass Spectrometry(DART-MS).Nearly all aconitine-type alkaloids can be desorbed and ionized in this method,including diester diterpenoid aconitines(DDAs),monoester diterpenoid aconitines(MDAs)and some other diterpenoid aconitines.The spectra of in situ analysis for the herbal pieces of aconitum plants are similar with that of their extracts.Radix Aconiti and Radix Aconiti Kusnezoffii can be distinguished from each other by the intensity differences of character fragment ions from MDAs,such as m/z 586,572,and 556.The qualified and unqualified herbal pieces can be also identified by the relative abundances of DDAs.The RSD of the relative abundances of some character ions at m/z 556,586,and 590 were 13.53%,4.03%,and 12.03%,respectively.So this in situ analytical method can identify both the types of Aconitum preparata and their quality.It provides the following advantages in the analysis of Chinese herbs:fast detection without much pretreatment,high-throughput analysis,and reduction of pollution without any organic solvent.

CeO_(2) doping boosted low-temperature NH3-SCR activity of FeTiOx catalyst:A microstructure analysis and reaction mechanistic study

FeTiOx has been recognized as an environmental-friendly and cost-effective catalyst for selective catalytic reduction(SCR)of NOx with NH3.Aimed at further improving the low-temperature DeNOx efficiency of FeTiOx catalyst,a simple strategy of CeO_(2) doping was proposed.The low-temperature(<250°C)NH3-SCR activity of FeTiOx catalyst could be dramatically enhanced by CeO2 doping,and the optimal composition of the catalyst was confirmed as FeCe_(0.2)TiOx,which performed a NOx conversion of 90%at ca.200°C.According to X-ray diffraction(XRD),Raman spectra and X-ray absorption fine structure spectroscopy(XAFS)analysis,FeCe_(0.2)TiOx showed low crystallinity,with Fe and Ce species well mixed with each other.Based on the fitting results of extended X-ray absorption fine structure(EXAFS),a unique Ce-O-Fe structure was formed in FeCe_(0.2)TiOx catalyst.The well improved specific surface area and the newly formed Ce-O-Fe structure dramatically contributed to the improvement of the redox property of FeCe_(0.2)TiOx catalyst,which was well confirmed by H2-temperature-programmed reduction(H2-TPR)and in situ XAFS experiments.Such enhanced redox capability could benefit the activation of NO and NH_(3) at low temperatures for NOx removal.The detailed reaction mechanism study further suggested that the facile oxidative dehydrogenation of NH_(3) to highly reactive-NH_(2) played a key role in enhancing the low-temperature NH_(3)-SCR performance of FeCe_(0.2)TiOx catalyst.

Two-dimensional correlation analysis of continuous online in situ ATR-FTIR on the adsorption of butyl xanthate at the surface of α-PbO

The adsorption behavior of butyl xanthate on the surface of lead oxide was investigated using continuous online in situ attenuated total reflectance Fourier transform infrared（ATR-FTIR） spectroscopy technique and two dimensional（2D） correlation analysis.The adsorbed layer studied was prepared by coating α-PbO particles onto the surfaces of the ZnSe crystal.The appearance of spectral peaks at 1203 cm^-1,1033 cm^-1 and their red shift indicated the formation and aggregation of xanthate at the surface of α-PbO.According to 1R intensity changes after rinsing with deionized water and a NaOH solution,the adsorption was proved to be a chemisorption type.The competition between xanthate and OH^- for the surfaces leads to desorption of xanthate at higher pH.The technique of 2D correlation ATR-FTIR spectroscopy was used to evaluate the changing order of spectral intensities in the adsorption process,and the results indicated that xanthate micelles were formed at the surfaces.The adsorption kinetics of butyl xanthate was found to be a pseudo-second-order reaction model and the adsorption capacity of butyl xanthate at α-PbO was as high as 281 mg g^-1 after 150 min.

Fur glowing under ultraviolet:in situ analysis of porphyrin accumulation in the skin appendages of mammals

Examples of photoluminescence(PL)are being reported with increasing frequency in a wide range of organisms from diverse ecosystems.However,the chemical basis of this PL remains poorly defined,and our understanding of its potential ecological function is still superficial.Among mammals,recent analyses have identified free-base por-phyrins as the compounds responsible for the reddish ultraviolet-induced photoluminescence(UV-PL)observed in the pelage of springhares and hedgehogs.However,the localization of the pigments within the hair largely remains to be determined.Here,we use photoluminescence multispectral imaging emission and excitation spec-troscopy to detect,map,and characterize porphyrinic compounds in skin appendages in situ.We also document new cases of mammalian UV-PL caused by free-base porphyrins in distantly related species.Spatial distribution of the UV-PL is strongly suggestive of an endogenous origin of the porphyrinic compounds.We argue that reddish UV-PL is predominantly observed in crepuscular and nocturnal mammals because porphyrins are photodegradable.Con-sequently,this phenomenon may not have a specific function in intra-or interspecific communication but rather represents a byproduct of potentially widespread physiological processes.

In situ speciation analysis and kinetic study of arsenic adsorption on ferrihydrite with surface-enhanced Raman spectroscopy

Arsenic pollution poses a serious threat to human health,and is one of the most concerning environmental problems worldwide.The adsorption,fixation,and dissolution behaviors of arsenic on the surface of iron-(hydr-)oxides influence the environmental routes of arsenic cycle geochemistry.Both inner-sphere and outer-sphere adsorption configurations of arsenic on iron oxides have been proposed based on X-ray adsorption spectra.However,there is no systematic study on the in situ speciation analysis and adsorption kinetics of these species at such interfaces,because of the lack of an efficient monitoring strategy.The correlation of surface speciation and environmental stability is still unknown.Here,a shell-isolated SiO_(2)@Ag@Au-based surface-enhanced Raman spectroscopy(SERS)platform was developed for speciation analysis of the adsorbed arsenic species by eliminating the chemical interaction between arsenic and silver.Using ferrihydrite as a typical iron oxide,the intrinsic Raman spectra of the inner-sphere(~830 cm^(−1))and outer-sphere(~660 cm^(−1))complexes at the adsorption interface were identified.For the first time,the in situ kinetic monitoring of the formation and transformation of these species was realized.By correlating the speciation to the sequential extraction results,the environmental stability of arsenic on ferrihydrite was shown to be closely related to the adsorption configuration.It was shown that stability can be significantly promoted by transforming loosely bonded species(outer-sphere complexes)into inner-sphere structures.Our work demonstrated the applicability of SERS with shell-isolated plasmonic particles for arsenic geochemical cycle monitoring and mechanism studies.It also provided a convenient tool for developing effective strategies for arsenic pollutant control and abatement.

In situ Rb-Sr dating of mica by LA-ICP-MS/MS

Mica exhibits a relatively high Rb/Sr ratio and possesses a closure temperature for the Rb-Sr isotope system that is higher than the ore-forming temperature range of low-to medium-temperature deposits.Consequently,utilizing the laser ablation(LA)technique for in situ Rb-Sr dating in mica constitutes a significant methodology for resolving the mineralization chronology of low-to medium-temperature hydrothermal ore deposits.In this study,we employed a combination of a triple quadrupole inductively coupled plasma mass spectrometer(ICP-MS/MS)and 193 nm LA system with SF_6as the reaction gas to achieve interference removal of~(87)Rb~+on~(87)Sr~+.We then developed an in situ Rb-Sr dating method for mica.In addition,an investigation was conducted to identify the factors that could influence the analytical accuracy of the method.Subsequently,we applied the developed method to carry out in situ Rb-Sr dating for the ZBH-25 biotite,a national primary reference material(GBW04439)for K-Ar dating,and yielded a younger age(ca.12%,relative standard deviation,RSD)than the reference K-Ar age when using NIST SRM 610 as the reference material for external calibration.This finding indicated that in the process of determining Rb-Sr ages for mica by LA-ICP-MS/MS,there are significant matrix effects between the NIST SRM 610 and the mica samples,resulting in inaccurate Rb-Sr ages.In response to this issue,a two-step calibration method is proposed here.Based on external calibration using NIST SRM 610,ZBH-25 biotite is employed as a second external reference material to perform a second calibration of the sample data to correct the matrix effect between the glass standards and the natural mica samples,thereby improving the accuracy of Rb-Sr dating by LA-ICP-MS/MS.Using the proposed method,in situ Rb-Sr dating by LA-ICP-MS/MS was performed on mica samples from monzonite exposed in Mt.Dromedary,New South Wales,Australia,porphyritic granodiorite in Fangshan pluton and albionite granite in the Gyirong area of Tibet.The obtained Rb-Sr age results show agreement with the recommended values within the analytical uncertainty,which serves to validate the accuracy and effectiveness of the proposed method.