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Bakin karfe da ake amfani da shi sosai da kuma nau'ikan da aka ƙera suna da juriya ga tsatsa a yanayi na yanayi saboda layin passivation wanda ya ƙunshi chromium oxide. Tsatsa da lalacewar ƙarfe galibi suna da alaƙa da lalata waɗannan yadudduka, amma ba kasafai suke faruwa ba tare da bayyanar rashin daidaituwar saman, ya danganta da matakin ƙananan ƙwayoyin cuta. A cikin wannan aikin, bambancin saman sinadarai na nanoscale, wanda aka gano ta hanyar nanoscope da nazarin chemometric, ba zato ba tsammani ya mamaye karyewa da tsatsa na cerium modified super duplex bakin karfe 2507 (SDSS) mai sanyi a lokacin lalacewarsa mai zafi. Kodayake na'urar daukar hoto ta X-ray ta nuna cikakken rufewa na layin Cr2O3 na halitta, aikin passivation na SDSS mai sanyi bai yi kyau ba saboda rarraba tsibirin nano mai arzikin Fe3+ a kan layin oxide na Fe/Cr. Wannan ilimin sikelin atomic yana ba da zurfin fahimtar tsatsa na bakin karfe kuma ana sa ran zai taimaka wajen yaƙi da tsatsa na irin waɗannan ƙarfe masu ƙarfe masu kama da juna.
Tun lokacin da aka ƙirƙiro ƙarfe mai bakin ƙarfe, an danganta kaddarorin hana lalata na ferrochrome da chromium, wanda ke samar da ƙarfi oxides/oxyhydroxides kuma yana nuna ɗabi'ar wucewa a yawancin muhalli. Idan aka kwatanta da ƙarfe na gargajiya (austenitic da ferritic) na bakin ƙarfe 1, 2, 3, super duplex bakin ƙarfe (SDSS) suna da juriyar tsatsa mafi kyau da kyawawan halayen injiniya. Ƙarfin injina yana ba da damar ƙira mai sauƙi da ƙanƙanta. Sabanin haka, SDSS mai tattalin arziki yana da juriya mai ƙarfi ga tsatsa da tsatsa mai ƙwanƙwasa, wanda ke haifar da tsawon rai na sabis, ta haka yana faɗaɗa aikace-aikacensa ga sarrafa gurɓataccen iska, kwantena na sinadarai, da masana'antar mai da iskar gas ta teku4. Duk da haka, kunkuntar yanayin zafi na maganin zafi da rashin kyawun tsari yana hana aikace-aikacen su na aiki. Saboda haka, an gyara SDSS don inganta aikin da ke sama. Misali, an gabatar da gyaran Ce a cikin SDSS 2507 (Ce-2507) tare da babban abun ciki na nitrogen6,7,8. Sinadarin ƙasa mai wuya (Ce) a cikin yawan da ya dace na 0.08 wt.% yana da tasiri mai kyau akan halayen injina na DSS, tunda yana inganta tsaftace hatsi da ƙarfin iyakokin hatsi. Haka kuma an inganta juriyar lalacewa da tsatsa, ƙarfin tauri da ƙarfin samarwa, da kuma sauƙin aiki mai zafi9. Yawan nitrogen na iya maye gurbin sinadarin nickel mai tsada, wanda hakan ke sa SDSS ya fi araha10.
Kwanan nan, SDSS ta lalace ta hanyar filastik a yanayin zafi daban-daban (cryogenic, sanyi da zafi) don cimma kyawawan halayen injiniya6,7,8. Duk da haka, kyakkyawan juriyar tsatsa na SDSS saboda kasancewar wani siririn fim ɗin oxide a saman yana shafar abubuwa da yawa kamar bambancin yanayi saboda kasancewar matakai daban-daban tare da iyakokin hatsi daban-daban, abubuwan da ba a so da kuma martani daban-daban. nakasar matakan austenitic da ferritic7. Saboda haka, nazarin halayen yanki na ƙananan ƙwayoyin cuta na irin waɗannan fina-finai har zuwa matakin tsarin lantarki ya zama mahimmanci don fahimtar tsatsa na SDSS kuma yana buƙatar dabarun gwaji masu rikitarwa. Zuwa yanzu, hanyoyin da ke da alaƙa da saman kamar Auger electron spectroscopy11 da X-ray photoelectron spectroscopy12,13,14,15 da hard X-ray photoemission microscopy (HAX-PEEM)16 gabaɗaya sun kasa gano bambance-bambancen sinadarai a cikin yadudduka na saman. yanayin sinadarai na abu ɗaya a wurare daban-daban na sararin nanoscale. Nazarce-nazarce da dama da aka yi kwanan nan sun danganta yadda sinadarin chromium ke aiki da kuma yadda ake lalata shi a cikin ƙarfen austenitic bakin ƙarfe17, ƙarfen martensitic18 da SDSS19,20. Duk da haka, waɗannan binciken sun fi mayar da hankali kan tasirin sinadarin Cr (misali, yanayin oxidation na Cr3+) akan juriyar tsatsa. Bambancin gefe a cikin yanayin oxidation na abubuwa na iya faruwa ta hanyar mahaɗan daban-daban tare da abubuwan da ke cikin su iri ɗaya, kamar ƙarfe oxides. Waɗannan mahaɗan, waɗanda suka gaji ƙaramin girma sakamakon maganin thermomechanical, suna kusa da juna, amma sun bambanta a cikin abun da ke ciki da yanayin oxidation16,21. Saboda haka, don gano fashewar fina-finan oxide da kuma ramin da ke biyo baya, ya zama dole a fahimci bambancin saman a matakin microscopic. Duk da waɗannan buƙatun, kimantawa na adadi kamar bambancin gefe a cikin oxidation, musamman ga Fe a sikelin nano- da atomic, har yanzu ba a gano shi ba, kuma dangantakarsa da juriyar tsatsa har yanzu ba a bincika ba. Har zuwa kwanan nan, yanayin sinadarai na abubuwa daban-daban, kamar Fe da Ca22, akan samfuran ƙarfe an siffanta su da adadi ta amfani da na'urar hangen nesa ta X-ray mai laushi (X-PEEM) a cikin wuraren hasken nanoscale synchrotron. Idan aka haɗa shi da na'urar hangen nesa ta X-ray mai saurin amsawa (XAS), X-PEEM yana ba da damar auna XAS tare da ƙudurin sarari da na spectral mai girma, yana ba da bayanai game da sinadarai game da abun da ke cikin abubuwan da yanayin sinadarainsu tare da ƙudurin sarari har zuwa sikelin nanometer ashirin da uku. Wannan lura da spectromicroscopic na farkon yana sauƙaƙa lura da sinadarai na gida kuma yana iya nuna canje-canjen sinadarai a cikin sararin layin ƙarfe wanda ba a taɓa bincika shi ba a baya.
Wannan binciken ya faɗaɗa fa'idodin PEEM wajen gano bambance-bambancen sinadarai a sikelin nano kuma ya gabatar da wata hanyar nazarin saman matakin atomic mai zurfi don fahimtar halayen lalata na Ce-2507. Yana amfani da hanyar kemometric ta K-means24 mai tarin yawa don zana kwatancen haɗin kai na sinadarai na duniya (hetero) na abubuwan da ke ciki, waɗanda aka gabatar da yanayin sinadarai a cikin wakilcin ƙididdiga. Sabanin tsatsa da lalata fim ɗin chromium oxide ya haifar a cikin yanayin gargajiya, ƙarancin rashin yarda da juriya ga tsatsa a halin yanzu ana danganta su da tsibiran nano masu arziki na Fe3+ kusa da layin oxide na Fe/Cr, wanda ƙila yana iya zama kaddarorin kariya. oxide yana lalata fim ɗin da aka yi wa dige kuma yana haifar da tsatsa.
An fara kimanta halayen lalata na nakasassu SDSS 2507 ta amfani da ma'aunin lantarki. A hoto na 1, an nuna lanƙwasa na Nyquist da Bode don samfuran da aka zaɓa a cikin ruwan acidic (pH = 1) na FeCl3 a zafin ɗaki. Zaɓaɓɓen electrolyte yana aiki azaman mai ƙarfi na oxidizing, yana nuna yanayin da fim ɗin passivation ke lalacewa. Kodayake kayan bai yi riƙo mai ƙarfi a zafin ɗaki ba, binciken ya ba da haske game da yiwuwar abubuwan da suka faru na gazawa da kuma tsatsa daga baya. An yi amfani da da'irar daidai (Hoto na 1d) don dacewa da bakan electrochemical impedance spectroscopy (EIS), kuma an nuna sakamakon daidaitawa masu dacewa a cikin Jadawali na 1. Semicircles marasa cikakke suna bayyana a cikin samfuran da aka yi wa magani da maganin zafi, yayin da semicircles masu matsewa suna bayyana a cikin takwarorinsu masu sanyi (Hoto na .1b). A cikin EIS spectroscopy, ana iya ɗaukar radius na semicircle a matsayin juriyar polarization (Rp)25,26. Rp na titin jirgin sama mai maganin mafita a cikin Tebur 1 yana da kusan 135 kΩ cm–2, duk da haka, ƙimar titin jirgin sama mai aikin zafi da sanyi sun yi ƙasa sosai, 34.7 da 2.1 kΩ cm–2, bi da bi. Wannan babban raguwa a cikin Rp yana nuna mummunan tasirin nakasar filastik akan juriyar wucewa da tsatsa, kamar yadda aka nuna a cikin rahotannin da suka gabata27,28,29,30.
zane-zanen Nyquist, b, c na impedance na Bode da kuma phase impedance, da kuma samfuran da'ira masu dacewa d, inda RS shine juriyar electrolyte, Rp shine juriyar polarization, kuma QCPE shine oxide na abin da ke cikin lokaci mai ɗorewa da ake amfani da shi don yin samfurin ƙarfin da ba shi da kyau (n). Ana yin ma'aunin EIS a cikin ƙarfin da'ira mai buɗewa.
An nuna ma'aunin lokaci guda a cikin taswirar Bode, tare da wani fili a cikin kewayon mita mai yawa wanda ke wakiltar juriyar electrolyte RS26. Yayin da mitar ke raguwa, impedance yana ƙaruwa kuma an sami kusurwar mataki mara kyau, yana nuna rinjayen capacitance. Kusurwar mataki tana ƙaruwa, tana riƙe da matsakaicin a kan kewayon mita mai faɗi, sannan ta ragu (Hoto na 1c). Duk da haka, a cikin dukkan shari'o'i uku, wannan matsakaicin har yanzu bai kai 90° ba, yana nuna halayen capacitive mara kyau saboda watsawar capacitive. Don haka, ana amfani da sinadarin lokaci na QCPE (CPE) don wakiltar rarrabawar capacitance tsakanin fuska da ke tasowa daga ƙaiƙayi ko rashin daidaituwa, musamman a sikelin atomic, geometry fractal, electrode porosity, non-uniform potential, da geometry tare da siffar electrodes31,32. CPE impedance:
inda j shine lambar tunani kuma ω shine mitar kusurwa. QCPE shine madaidaicin mita wanda ba shi da alaƙa da yankin buɗewa mai tasiri na electrolyte. n lambar ƙarfi ce mara girma wacce ke bayyana karkacewar capacitor daga madaidaicin capacitance, watau idan n ya kusa da 1, CPE ta fi kusa da capacitive kawai, yayin da idan n ya kusa da sifili, yana kama da juriya. Ƙananan karkacewar n, kusa da 1, suna nuna halayen capacitive mara kyau na saman bayan gwaje-gwajen polarization. QCPE na SDSS mai sanyi ya fi na takwarorinsa girma sosai, ma'ana ingancin saman bai yi kama da juna ba.
Daidai da yawancin halayen juriya ga tsatsa na ƙarfen bakin ƙarfe, yawan Cr da ke cikin SDSS gabaɗaya yana haifar da kyakkyawan juriya ga tsatsa na SDSS saboda kasancewar fim ɗin kariya mai wucewa akan saman17. Irin waɗannan fina-finan wucewa galibi suna da wadataccen Cr3+ oxides da/ko hydroxides, galibi tare da Fe2+, Fe3+ oxides da/ko (oxy) hydroxides33. Duk da daidaiton saman iri ɗaya, layin oxide mai wucewa, kuma babu fashewar saman da aka gani bisa ga ma'aunin ƙananan ƙwayoyin cuta6,7, halayen tsatsa na SDSS mai zafi da sanyi ya bambanta, don haka bincike mai zurfi game da halayen ƙananan ƙwayoyin cuta ya zama dole don lalacewar ƙarfe.
An yi nazarin ƙananan tsarin ƙarfe mara kyau ta hanyar amfani da hasken X-ray na ciki da na synchrotron masu ƙarfi (Karin Figures 1, 2). An bayar da cikakken bincike a cikin Ƙarin Bayani. Kodayake akwai yarjejeniya gabaɗaya kan nau'in babban matakin, an sami bambance-bambance a cikin manyan sassan, waɗanda aka jera a cikin Tebur na Ƙarin 1. Waɗannan bambance-bambancen na iya faruwa ne saboda ƙananan sassan lokaci marasa daidaituwa a saman da kuma a cikin girma, waɗanda zurfin gano X-ray (XRD) daban-daban ke shafar su.) tare da hanyoyin samar da makamashi daban-daban na photons na faruwa34. Ƙananan sassan austenite a cikin samfuran sanyi da aka birgima ta hanyar XRD daga tushen dakin gwaje-gwaje suna nuna mafi kyawun passivation sannan mafi kyawun juriya ga tsatsa35, yayin da sakamakon da ya fi daidai da ƙididdiga ya nuna akasin haka a cikin sassan lokaci. Bugu da ƙari, juriyar tsatsa na ƙarfe kuma ya dogara da matakin tsaftace hatsi, rage girman hatsi, ƙaruwa a cikin ƙananan canje-canje da yawan katsewa da ke faruwa yayin maganin thermomechanical36,37,38. Samfuran da aka yi amfani da su sosai sun nuna yanayin hatsi mai kama da micron, yayin da zoben santsi da aka gani a cikin samfuran da aka yi amfani da su a cikin sanyi (Hoto na 3) sun nuna ingantaccen gyaran hatsi don nanosize a cikin aikin da ya gabata. Wannan ya kamata ya fi son fim ɗin da ba ya aiki. samuwar da ƙaruwar juriyar tsatsa. Yawancin lokaci yawan nakasa yana da alaƙa da ƙarancin juriya ga rami, wanda ya yi daidai da ma'aunin lantarki.
An yi nazarin canje-canje a yanayin sinadarai na ƙananan yankuna na manyan abubuwan ta hanyar amfani da X-PEEM. Duk da cewa akwai ƙarin abubuwan haɗawa, an zaɓi Cr, Fe, Ni da Ce39 a nan, tunda Cr shine babban abin da ke samar da fim ɗin da ba ya aiki, Fe shine babban abin da ke cikin ƙarfe, kuma Ni yana haɓaka passivation kuma yana daidaita matakin ferrite-austenitic. Tsarin da gyare-gyare shine manufar Ce. Ta hanyar daidaita kuzarin hasken synchrotron, XAS ta kama manyan halayen Cr (gefen L2.3), Fe (gefen L2.3), Ni (gefen L2.3), da Ce (gefen M4.5) daga saman. -2507 SDSS. An gudanar da nazarin bayanai masu dacewa ta hanyar haɗa da daidaita kuzari tare da bayanan da aka buga (misali XAS akan Fe L2, haƙarƙari 340,41).
A kan hoto na 2 yana nuna hotunan X-PEEM na aikin zafi (Hoto na 2a) da na'urar birgima mai sanyi (Hoto na 2d) Ce-2507 SDSS da gefunan XAS Cr da Fe L2,3 masu dacewa a wurare daban-daban da aka yiwa alama. Gefen L2,3 XAS yana bincika yanayin electrons 3d marasa sha'awa bayan ɗaukar hoto a matakan raba-raga na juyawa na 2p3/2 (gefen L3) da 2p1/2 (gefen L2). An samo bayanai game da yanayin valence na Cr daga nazarin X-ray diffraction na gefen L2,3 a cikin Hoto na 2b,d. Kwatanta hanyar haɗi. 42, 43 ya nuna cewa an lura da kololuwa huɗu na A (578.3 eV), B (579.5 eV), C (580.4 eV), da D (582.2 eV) kusa da gefen L3, suna nuna ions na Cr3+ octahedral, Cr2O3 masu dacewa. Gwaje-gwajen gwaje-gwajen sun yi daidai da lissafin ka'idoji, kamar yadda aka nuna a cikin faifan b da e, waɗanda aka samo daga lissafin filin lu'ulu'u da yawa a mahaɗin Cr L2.3 ta amfani da filin lu'ulu'u na 2.0 eV44. Duk saman SDSS mai zafi da na sanyi an rufe su da wani Layer na Cr2O3 iri ɗaya.
Hoton zafi na X-PEEM SDSS mai zafi wanda ya yi daidai da gefen b Cr L2.3 da gefen c Fe L2.3, d Hoton zafi X-PEEM na SDSS mai sanyi wanda ya yi daidai da gefen e Cr L2.3 da f Fe L2.3 na gefen (e). Siffar XAS da aka zana a wurare daban-daban na sarari wanda aka yiwa alama akan hotunan zafi (a, d) ta layukan lemu masu dige-dige a cikin (b) da (e) suna wakiltar siffar XAS da aka kwaikwayi na Cr3+ tare da ƙimar filin lu'ulu'u na 2.0 eV. Ga hotunan X-PEEM, ana amfani da palet ɗin zafi don inganta iya karanta hoto, inda launuka daga shuɗi zuwa ja suke daidai da ƙarfin shan X-ray (daga ƙasa zuwa sama).
Ko da kuwa yanayin sinadarai na waɗannan abubuwan ƙarfe, yanayin sinadarai na ƙarin abubuwan haɗin Ni da Ce don samfuran biyu ya kasance iri ɗaya. Ƙarin zane. A hoto na 5-9 yana nuna hotunan X-PEEM da kuma spectra XAS masu dacewa don Ni da Ce a wurare daban-daban akan saman samfuran da aka yi amfani da su da zafi da sanyi. Ni XAS yana nuna yanayin iskar shaka na Ni2+ akan dukkan saman da aka auna na samfuran da aka yi amfani da su da zafi da sanyi (Tattaunawa ta Ƙarin). Abin lura ne cewa a yanayin samfuran da aka yi amfani da su da zafi, ba a lura da siginar XAS na Ce ba, yayin da aka lura da bakan Ce3+ na samfuran da aka yi amfani da su da sanyi a wani lokaci. Lura da tabo na Ce a cikin samfuran da aka yi amfani da su da sanyi ya nuna cewa Ce galibi yana wanzuwa a cikin nau'in hazo.
A cikin SDSS mai nakasa a yanayin zafi, babu wani canji na gida a cikin XAS da aka gani a gefen Fe L2.3 (Hoto na 2c). Duk da haka, kamar yadda aka nuna a cikin hoto na 2f, matrix na Fe yana canza yanayin sinadaransa ta hanyar microscopic a wurare bakwai da aka zaɓa bazuwar a cikin SDSS mai sanyi. Bugu da ƙari, don samun cikakken ra'ayi game da canje-canje a cikin yanayin Fe a wurare da aka zaɓa a cikin Hoto na 2f, an gudanar da nazarin saman gida (Hoto na 3 da Hoto na Ƙari na 10) inda aka zaɓi ƙananan yankuna masu zagaye. An yi kwaikwayon siginar XAS na gefen Fe L2,3 na tsarin α-Fe2O3 da oxides na Fe2+ octahedral ta amfani da ƙididdigar filin lu'ulu'u masu yawa ta amfani da filayen lu'ulu'u na 1.0 (Fe2+) da 1.0 (Fe3+)44. Mun lura cewa α-Fe2O3 da γ-Fe2O3 suna da daidaitattun daidaito na gida45,46, Fe3O4 yana da haɗin Fe2+ da Fe3+,47, da FeO45 a matsayin oxide mai divalent na Fe2+ (3d6). Mun lura cewa α-Fe2O3 da γ-Fe2O3 suna da daidaitattun daidaito na gida45,46, Fe3O4 yana da haɗin Fe2+ da Fe3+,47, da FeO45 a matsayin oxide mai divalent na Fe2+ (3d6).Lura cewa α-Fe2O3 da γ-Fe2O3 suna da daidaitattun daidaito na gida45,46, Fe3O4 ya haɗa duka Fe2+ da Fe3+,47 da FeO45 a cikin nau'in oxide mai divalent Fe2+ (3d6).Lura cewa α-Fe2O3 da γ-Fe2O3 suna da daidaitattun daidaito na gida45,46, Fe3O4 yana da haɗuwa da Fe2+ da Fe3+,47 kuma FeO45 yana aiki azaman divalent Fe2+ oxide (3d6). Duk ions na Fe3+ a cikin α-Fe2O3 suna da matsayi na Oh kawai, yayin da γ-Fe2O3 yawanci ana bayyana shi azaman Fe3+ t2g [Fe3+5/3V1/3] misali O4 spinel tare da guraben aiki a cikin misalan matsayi. Saboda haka, ions na Fe3+ a cikin γ-Fe2O3 suna da matsayi na Td da Oh. Kamar yadda aka ambata a cikin aikin da ya gabata, kodayake rabon ƙarfi na biyu sun bambanta, rabon ƙarfi na su misali/t2g shine ≈1, yayin da a wannan yanayin rabon ƙarfi da aka lura misali/t2g shine kusan 1. Wannan ya kawar da yiwuwar Fe3+ kawai ya kasance a wannan yanayin. Idan aka yi la'akari da yanayin Fe3O4 tare da haɗin Fe2+ da Fe3+, an san cewa fasalin farko mai rauni (mai ƙarfi) a gefen L3 na Fe yana nuna ƙaramin rashin zama a cikin yanayin t2g. Wannan ya shafi Fe2+ (Fe3+), wanda ke nuna ƙaruwa a cikin alamar farko da ke nuna ƙaruwa a cikin abun ciki na Fe2+47. Waɗannan sakamakon sun nuna cewa Fe2+ da γ-Fe2O3, α-Fe2O3 da/ko Fe3O4 sun fi yawa a saman da aka naɗe da sanyi na mahaɗan.
An faɗaɗa hotunan zafin lantarki na hasken lantarki na hasken lantarki na (a, c) da (b, d) na XAS a gefen Fe L2,3 a wurare daban-daban na sarari a cikin yankuna da aka zaɓa 2 da E a cikin Hotuna na 2d.
An zana bayanan gwaji da aka samu (Hoto na 4a da Hoto na Ƙari na 11) kuma an kwatanta su da na sinadarai masu tsarki 40, 41, 48. Ainihin, an lura da nau'ikan ... A bisa ga abubuwan da aka gani a gani (Hoto na 4a), dukkan sassan Fe guda uku, wato Fe0, Fe2+, da Fe3+, suna nan a saman SDSS da aka yi nazari a kai. Rabon ƙarfin da aka ƙididdige L2/L3 shi ma ya nuna kasancewar dukkan sassan uku.
a Bayanan gwaji guda uku da aka lura daban-daban (layukan ƙarfi XAS-1, XAS-2 da XAS-3 sun yi daidai da 2-a, 2-b da E-3 a cikin Hoto na 2 da Hoto na 3) idan aka kwatanta da kwatancen XAS na kwatancen, octahedrons Fe2+, Fe3+, ƙimar filin lu'ulu'u na 1.0 eV da 1.5 eV, bi da bi, b–d Bayanan gwaji da aka auna (XAS-1, XAS-2, XAS-3) da bayanan LCF da aka inganta (layin baƙi mai ƙarfi), da kwatanta mizanin XAS-3 da Fe3O4 (yanayin gauraye na Fe) da Fe2O3 (tsarin Fe3+).
An yi amfani da haɗin layi (LCF) wanda ya dace da ma'auni uku40,41,48 don auna abun da ke cikin ƙarfe oxide. An aiwatar da LCF ga zaɓaɓɓun siffofi uku na Fe L-edge XAS waɗanda ke nuna mafi girman bambanci, wato XAS-1, XAS-2 da XAS-3, kamar yadda aka nuna a Hoto na 4b-d. Ga kayan haɗin LCF, an yi la'akari da 10% Fe0 a duk lokuta saboda ƙaramin gefen da muka lura a cikin duk bayanai da kuma gaskiyar cewa ƙarfe mai ƙarfe shine babban ɓangaren ƙarfe. Hakika, zurfin gwajin X-PEEM don Fe (~6 nm)49 ya fi girma fiye da kauri na Layer oxidation da aka kiyasta (dan kadan fiye da 4 nm), wanda ke ba da damar gano sigina daga matrix na ƙarfe (Fe0) a ƙarƙashin layin wucewa. Hakika, zurfin gwajin X-PEEM don Fe (~6 nm)49 ya fi girma fiye da kauri na Layer oxidation da aka kiyasta (dan kadan fiye da 4 nm), wanda ke ba da damar gano sigina daga matrix na ƙarfe (Fe0) a ƙarƙashin layin wucewa. Действительно, пробная глубина X-PEEM для Fe (~ 6 нм) 49 больше, чем предполагаемая толщина слоя окислоя окислоя позволяет обнаружить сигнал от железной матрицы (Fe0) под пассивирующим слоем. Hakika, zurfin binciken X-PEEM na Fe (~6 nm)49 ya fi kauri da ake tsammani na Layer oxidation (dan kadan fiye da 4 nm), wanda hakan ke sa ya yiwu a gano siginar daga matrix na ƙarfe (Fe0) a ƙarƙashin Layer passivation.A zahiri, X-PEEM yana gano Fe (~6 nm)49 zurfi fiye da kauri da ake tsammani na layin oxide (ƙasa da 4 nm), wanda ke ba da damar gano sigina daga matrix na ƙarfe (Fe0) a ƙarƙashin layin passivation. An yi haɗuwa iri-iri na Fe2+ da Fe3+ don nemo mafi kyawun mafita ga bayanan gwaji da aka lura. A kan hoto na 4b yana nuna haɗin Fe2+ da Fe3+ a cikin bakan XAS-1, inda rabon Fe2+ da Fe3+ suke kusa, kusan 45%, wanda ke nuna yanayin iskar shaka na Fe. Yayin da ga bakan XAS-2, kashi na Fe2+ da Fe3+ ya zama ~30% da 60%, bi da bi. Abun da ke cikin Fe2+ ya yi ƙasa da na Fe3+. Rabon Fe2+ zuwa Fe3 na 1:2 yana nufin cewa ana iya samar da Fe3O4 a daidai rabon ions na Fe. Bugu da ƙari, ga bakan XAS-3, kashi-kashi na Fe2+ da Fe3+ sun canza zuwa ~10% da 80%, wanda ke nuna babban juyi na Fe2+ zuwa Fe3+. Kamar yadda aka ambata a sama, Fe3+ na iya fitowa daga α-Fe2O3, γ-Fe2O3 ko Fe3O4. Don fahimtar tushen Fe3+ mafi yuwuwar, an zana bakan XAS-3 tare da ma'auni daban-daban na Fe3+ a cikin Hoto na 4e wanda ke nuna kamanceceniya da dukkan ma'auni guda biyu lokacin da aka yi la'akari da Peak B. Duk da haka, ƙarfin kafada (A: daga Fe2+) da rabon ƙarfi B/A suna nuna cewa bakan XAS-3 yana kusa da amma ba iri ɗaya da na γ-Fe2O3 ba. Idan aka kwatanta da babban γ-Fe2O3, ƙarfin Fe 2p XAS na kololuwar A SDSS ya ɗan fi girma (Hoto na 4e), wanda ke nuna babban ƙarfin Fe2+. Duk da cewa bakan XAS-3 yayi kama da na γ-Fe2O3, inda Fe3+ yake a cikin matsayi na Oh da Td, gano yanayin valence daban-daban da daidaitawa kawai ta hanyar gefen L2,3 ko rabon ƙarfin L2/L3 har yanzu matsala ce. batu mai maimaitawa na tattaunawa saboda sarkakiyar abubuwan da ke cikin bakan ƙarshe41.
Baya ga bambancin yanayin sinadarai na yankunan da aka zaɓa da aka bayyana a sama, an tantance bambancin sinadarai na duniya na muhimman abubuwan Cr da Fe ta hanyar rarraba dukkan nau'ikan XAS da aka samu a saman samfurin ta amfani da hanyar haɗa abubuwa ta hanyar K. An saita bayanan gefen Cr L ta yadda za su samar da ƙungiyoyi biyu mafi kyau waɗanda aka rarraba a sarari a cikin samfuran da aka yi amfani da su da zafi da sanyi da aka nuna a cikin Hoto na 5. A bayyane yake cewa ba a lura da canje-canje a cikin tsarin gida ba, tunda centroids biyu na nau'ikan XAS Cr suna da kama sosai. Waɗannan siffofi na nau'ikan guda biyu kusan iri ɗaya ne da waɗanda suka yi daidai da Cr2O342, wanda ke nufin cewa layukan Cr2O3 suna rarrabawa daidai gwargwado akan SDSS.
tarin K-na nufin yankunan L-gefen Cr, b centroids masu dacewa da XAS. Sakamakon kwatancen K-na nufin X-PEEM na SDSS mai sanyi: c clusters na yankunan K-na nufin gefen Cr L2,3 da d masu dacewa da XAS.
Don kwatanta taswirar gefen FeL mai rikitarwa, ana amfani da ƙungiyoyi huɗu da biyar da aka inganta da kuma centroids ɗinsu masu alaƙa (rarraba spectral) don samfuran da aka yi amfani da su da zafi da kuma waɗanda aka yi sanyi, bi da bi. Saboda haka, ana iya samun kashi (%) na Fe2+ da Fe3+ ta hanyar daidaita LCF da aka nuna a Hoto na 4. An yi amfani da Epseudo mai yuwuwar pseudoelectrode a matsayin aikin Fe0 don bayyana rashin daidaituwar microchemical na fim ɗin oxide na saman. Ana kimanta Epseudo kusan ta hanyar ƙa'idar haɗakarwa,
inda \(\rm{E}_{\rm{Fe}/\rm{Fe}^{2 + (3 + )}}\) yayi daidai da \(\rm{Fe} + 2e^ – \to\rm {Fe}^{2 + (3 + )}\), wanda shine 0.440 da 0.036 V, bi da bi. Yankunan da ke da ƙarancin ƙarfin suna da mafi girman abun ciki na mahaɗan Fe3+. Rarraba mai yuwuwa a cikin samfurin da aka canza yanayin zafi yana da hali mai layi tare da matsakaicin canji na kusan 0.119 V (Hoto na 6a,b). Wannan rarraba mai yuwuwa yana da alaƙa da yanayin saman (Hoto na 6a). Ba a lura da wasu canje-canje masu alaƙa da matsayi a cikin ciki na lamellar ba (Hoto na 6b). Akasin haka, don haɗakar oxides daban-daban tare da abubuwan da ke ciki daban-daban na Fe2+ da Fe3+ a cikin SDSS mai sanyi, ana iya ganin yanayin da ba shi da daidaito na ƙarfin da ba daidai ba (Hoto na 6c, d). Fe3+ oxides da/ko (oxy) hydroxides sune manyan abubuwan da ke lalata ƙarfe kuma suna iya shiga cikin iskar oxygen da ruwa50. A wannan yanayin, ana iya ganin cewa tsibiran da ke da arzikin Fe3+ suna rarrabawa a cikin gida kuma ana iya ɗaukar su a matsayin yankunan tsatsa. A wannan yanayin, za a iya ɗaukar gradient a cikin filin yuwuwar, maimakon cikakken ƙimar yuwuwar, a matsayin alamar gano wuraren tsatsa masu aiki51. Wannan rarrabawar da ba ta dace ba ta Fe2+ da Fe3+ a saman SDSS mai sanyi na iya canza halayen sinadarai na gida da kuma samar da ingantaccen yanki a saman fim ɗin oxide da halayen tsatsa, ta haka yana barin matrix na ƙarfe na ƙasa ya ci gaba da lalacewa, yana haifar da rashin daidaituwa na ciki. da kuma rage halayen kariya na layin wucewa.
Ƙungiyoyin matsakaicin K na yankunan gefen Fe L2,3 da kuma centroids na XAS masu dacewa don a–c X-PEEM mai zafi da d–f SDSS mai sanyi. a, d K-na nufin taswirar rukuni da aka lulluɓe akan hoton X-PEEM. An ambaci ƙiyasin ƙarfin pseudoelectrode (epseudo) tare da zane-zanen rukuni na K. Hasken hoton X-PEEM kamar launi a Hoto na 2 yana daidai da ƙarfin sha X-ray.
Yanayin sinadarai daban-daban na Fe, wanda yake daidai da Cr, yana haifar da asalin fashewar fim ɗin oxide da kuma tsatsa a cikin Ce-2507 mai zafi da sanyi. Wannan siffa ta Ce-2507 mai sanyi an san ta sosai. Dangane da samuwar oxides da hydroxides na Fe a cikin iskar yanayi, waɗannan halayen an rufe su a cikin wannan aikin azaman halayen tsaka tsaki:
Dangane da ma'aunin X-PEEM, abin da ke sama ya faru a cikin waɗannan yanayi. Ƙaramin kafada da ya dace da Fe0 yana da alaƙa da ƙarfen ƙarfe da ke ƙarƙashinsa. Haɗakar ƙarfe Fe tare da muhalli yana haifar da samuwar Layer na Fe(OH)2 (daidaitawa (5)), wanda ke ƙara siginar Fe2+ a cikin XAS na gefen L na Fe. Tsawon lokacin da aka ɗauka ga iska zai haifar da samuwar Fe3O4 da/ko Fe2O3 oxides bayan Fe(OH)252,53. Nau'i biyu na Fe mai karko, Fe3O4 da Fe2O3, suma suna iya samuwa a cikin Layer mai karewa mai wadata na Cr3+, inda Fe3O4 ke fifita tsarin iri ɗaya da haɗin kai. Kasancewar duka biyun yana haifar da yanayin iskar shaka (bakan XAS-1). Bakan XAS-2 galibi yayi daidai da Fe3O4. Yayin da bakan XAS-3 da aka gani a wurare da yawa ya nuna cikakken juyawa zuwa γ-Fe2O3. Tunda hasken X-ray da ba a rufe ba yana da zurfin shiga na kimanin nm 50, siginar da ke fitowa daga ƙasan yana haifar da ƙarin ƙarfi na kololuwar A.
Bakan XRD ya nuna cewa bangaren Fe a cikin fim ɗin oxide yana da tsari mai layi, wanda aka haɗa shi da layin Cr oxide. Sabanin yanayin lalatawa na lalata saboda rashin daidaituwar gida na Cr2O317, duk da daidaitaccen Layer na Cr2O3 a cikin wannan binciken, an lura da ƙarancin juriyar tsatsa a wannan yanayin, musamman ga samfuran da aka naɗe da sanyi. Ana iya fahimtar halayen da aka lura a matsayin bambancin yanayin iskar shaka na sinadarai na saman Layer (Fe) wanda ke shafar aikin tsatsa. Saurin canja wurin ƙarfe ko ions na oxygen a cikin raga saboda irin wannan stoichiometry na saman (Fe oxide) da ƙananan Layer (Cr oxide)52,53 yana haifar da kyakkyawar hulɗa (mannewa) a tsakaninsu. Wannan, bi da bi, yana inganta juriyar tsatsa. Saboda haka, ci gaba da stoichiometry, watau yanayin iskar shaka ɗaya na Fe, ya fi dacewa da canje-canjen stoichiometric kwatsam. SDSS mai nakasa a yanayin zafi yana da saman da ya fi daidaito da kuma Layer mai kauri, wanda ke ba da juriyar tsatsa mafi kyau. Duk da haka, ga SDSS mai sanyi, kasancewar tsibiran Fe3+ masu arzikin Fe3+ a ƙarƙashin layin kariya yana lalata amincin saman kuma yana haifar da tsatsa ta galvanic na substrate da ke kusa, wanda ke haifar da raguwar Rp (Tebur 1) a cikin siginar EIS da juriyar tsatsa. Saboda haka, tsibiran da aka rarraba a cikin gida masu arzikin Fe3+ saboda lalacewar filastik galibi suna shafar aikin juriyar tsatsa, wanda shine babban ci gaba a cikin wannan aikin. Saboda haka, wannan binciken yana gabatar da siginar spectromicrographs na rage juriyar tsatsa saboda nakasar filastik na samfuran SDSS da aka yi nazari a kansu.
Bugu da ƙari, yayin da haɗakar ƙasa mai wuya a cikin ƙarfe mai matakai biyu ke aiki mafi kyau, hulɗar wannan ƙarin abu tare da matrix na ƙarfe ɗaya dangane da ɗabi'ar tsatsa ya kasance mai wahala bisa ga lura da na'urar hangen nesa ta spectroscopic. Siginar Ce (tare da gefen XAS M) tana bayyana ne kawai a wurare kaɗan yayin birgima mai sanyi, amma tana ɓacewa yayin lalacewar zafi na SDSS, yana nuna ajiyar Ce na gida a cikin matrix na ƙarfe maimakon haɗakarwa iri ɗaya. Kodayake ba a inganta halayen injiniya na SDSS6,7 ba, kasancewar REE yana rage girman abubuwan da aka haɗa kuma ana tsammanin yana hana rami a asalin54.
A ƙarshe, wannan aikin ya bayyana tasirin bambancin saman da ke tattare da tsatsa na 2507 SDSS da aka gyara da cerium ta hanyar ƙididdige sinadaran da ke cikin sassan nanoscale. Mun amsa tambayar dalilin da yasa bakin ƙarfe ke lalacewa ko da an shafa shi da wani Layer na oxide mai kariya ta hanyar yin nazarin tsarin microstructure, yanayin sinadarai na siffofin saman da sarrafa sigina ta amfani da clustering na K-means. An tabbatar da cewa tsibiran Fe3+ masu arziki, gami da haɗin kai na octahedral da tetrahedral a cikin tsarin gauraye na Fe2+/Fe3+, tushen lalata fim ɗin oxide ne kuma tushen tsatsa na SDSS mai sanyi. Tsibiran Nano da Fe3+ ke mamaye suna haifar da mummunan juriya na tsatsa ko da a gaban isasshen Layer na Cr2O3 mai wucewa. Baya ga ci gaban hanyoyin da aka samu wajen tantance tasirin bambancin sinadarai na nanoscale akan tsatsa, ana sa ran wannan aikin zai zaburar da hanyoyin injiniya don inganta juriya na tsatsa na bakin ƙarfe yayin yin ƙarfe.
Don shirya ingots na Ce-2507 SDSS da aka yi amfani da su a cikin wannan binciken, an narkar da abubuwan da aka haɗa, gami da ƙarfen Fe-Ce mai ƙarfi da aka rufe da bututun ƙarfe tsarkakakke, a cikin tanda mai matsakaicin mita 150 don samar da ƙarfe mai narkewa sannan a zuba su cikin ƙirar siminti. An jera abubuwan da aka auna (wt%) a cikin Tebur na Ƙarin Bayani na 2. Da farko ana yin ingot ɗin da zafi zuwa tubalan. Sannan an rufe ƙarfen a zafin 1050°C na mintuna 60 zuwa ga wani maganin da ya yi ƙarfi, sannan a kashe shi a cikin ruwa zuwa zafin ɗaki. An yi nazarin samfuran da aka yi nazari dalla-dalla ta amfani da TEM da DOE don nazarin matakai, girman hatsi da yanayin halittarsa. Ana iya samun ƙarin bayani game da samfura da tsarin samarwa a wasu tushe6,7.
An sarrafa samfuran silinda (φ10 mm × 15 mm) don matsi mai zafi tare da axis na silinda a layi ɗaya da alkiblar nakasassu na tubalin. An yi matsi mai zafi mai yawa a cikin ƙimar matsin lamba akai-akai a cikin kewayon 0.01-10 s-1 a yanayin zafi daban-daban a cikin kewayon 1000-1150°C ta amfani da na'urar kwaikwayo ta zafi ta Gleeble-3800. Kafin nakasassu, an dumama samfuran a zafin da aka zaɓa a cikin ƙimar 10 °C s-1 na tsawon mintuna 2 don kawar da ƙimar zafin jiki. Bayan cimma daidaiton zafin jiki, an canza samfuran zuwa ƙimar matsin lamba ta gaske ta 0.7. Bayan nakasassu, ana kashe su nan da nan da ruwa don kula da tsarin nakasassu. Sannan an yanke samfuran da aka taurare a layi ɗaya da alkiblar matsewa. Don wannan binciken na musamman, mun zaɓi samfurin da aka taurare a 1050°C, 10 s-1 saboda ƙarancin tauri fiye da sauran samfuran7.
An gwada samfuran ma'aunin Ce-2507 mai girma (80 × 10 × 17 mm3) akan injin LG-300 mai nakasa mai matakai uku, wanda ya samar da mafi kyawun halayen injiniya tsakanin duk sauran azuzuwan nakasa6. Rage yawan tazara da kauri sun kasance 0.2 m·s-1 da 5% ga kowane hanya, bi da bi.
An yi amfani da wurin aiki na lantarki na Autolab PGSTAT128N don auna SDSS ta hanyar lantarki bayan an yi birgima da sanyi zuwa raguwar kauri 90% (daidai gwargwado na gaske 1.0) da kuma matsi mai zafi zuwa nau'in gaskiya 0.7 a 1050 oC da 10 s-1. Wurin aiki yana da ƙwayar lantarki mai uku-electrode tare da cikakken electrode calomel a matsayin electrode na tunani, electrode na counter graphite, da samfurin SDSS a matsayin electrode mai aiki. An yanke samfuran zuwa silinda masu diamita na 11.3 mm, zuwa gefunan da aka haɗa wayoyin jan ƙarfe. Sannan an zuba samfurin da resin epoxy, yana barin yanki mai aiki na 1 cm2 a matsayin electrode mai aiki (ƙasa na saman samfurin silinda). Yi amfani da hankali yayin wargaza epoxy da kuma lokacin yin yashi da gogewa na gaba don guje wa fashewa. Ana lanƙwasa saman aiki kuma an goge shi da dakatarwar goge lu'u-lu'u mai girman micron 1, an tsaftace shi da ruwa mai narkewa da ethanol kuma an busar da shi a cikin iska mai sanyi. Kafin a auna sinadaran lantarki, an fallasa samfuran da aka goge a iska na tsawon kwanaki da dama don samar da fim ɗin oxide na halitta. An yi amfani da ruwan FeCl3 (6.0 wt.%), wanda aka daidaita da HCl zuwa pH = 1.0 ± 0.01, don hanzarta lalata ƙarfe mai kauri 55, tunda ana samunsa a cikin yanayi masu tsauri inda ions na chloride ke da ƙarfin oxidizing mai ƙarfi da ƙarancin pH kamar yadda ASTM ta ƙayyade. Ka'idojin da aka gabatar sune G48 da A923. An nutsar da samfuran a cikin maganin gwaji na tsawon awa 1 kafin a ɗauki kowane ma'auni don isa ga yanayin da ke kusa da tsayayye. Don samfuran da aka yi amfani da su da zafi da kuma waɗanda aka yi amfani da su da sanyi, kewayon mitar auna impedance shine 1 × 105 ~ 0.1 Hz, kuma ƙarfin buɗewa (OPS) shine 5 mV, wanda shine 0.39, 0.33, da 0.25 VSCE, bi da bi. Kowace gwajin lantarki na kowane samfurin an maimaita shi aƙalla sau uku a ƙarƙashin yanayi ɗaya don tabbatar da sake haifar da bayanai.
Don ma'aunin HE-SXRD, an auna tubalan ƙarfe mai siffar murabba'i mai tsawon ƙafa 1 × 1 × 1.5 mm3 a kan layin Brockhouse mai ƙarfi a CLS, Kanada don ƙididdige tsarin matakin56. An gudanar da tattara bayanai a zafin ɗaki a cikin tsarin Debye-Scherrer ko tsarin sufuri. Tsawon tsawon hasken X da aka daidaita zuwa ma'aunin LaB6 shine 0.212561 Å, wanda yayi daidai da 58 keV, wanda ya fi na Cu Kα (8 keV) wanda aka saba amfani da shi azaman tushen hasken X-ray na dakin gwaje-gwaje. Ana sanya samfurin a nesa na 740 mm daga na'urar ganowa. Girman gano kowane samfurin shine 0.2 × 0.3 × 1.5 mm3, wanda aka ƙayyade ta girman katako da kauri samfurin. An tattara kowanne daga cikin waɗannan bayanai ta amfani da na'urar gano yankin Perkin Elmer, na'urar gano X-ray mai faɗi, pixels 200 µm, 40 × 40 cm2, ta amfani da lokacin fallasa na daƙiƙa 0.3 da firam 120.
An gudanar da ma'aunin X-PEEM na tsarin samfura guda biyu da aka zaɓa a tashar ƙarshen PEEM na layin Beamline MAXPEEM a cikin dakin gwaje-gwaje na MAX IV (Lund, Sweden). An shirya samfuran kamar yadda ake yi da ma'aunin lantarki. An ajiye samfuran da aka shirya a cikin iska na tsawon kwanaki da yawa kuma an cire gas ɗin a cikin ɗakin injin mai ƙarfi kafin a haskaka su da photons na synchrotron. Ana samun ƙudurin kuzarin hasken ta hanyar auna bakan fitarwa na ion daga N 1 s zuwa 1\(\pi _g^ \ast\) na yankin motsawa tare da hv = 401 eV a cikin N2 da dogaro da kuzarin photon akan E3/2.57. Daidaiton bakan ya ba ΔE (bakan layi) ~0.3 eV akan kewayon kuzarin da aka auna. Saboda haka, an kiyasta ƙudurin ƙarfin hasken rana shine E/∆E = 700 eV/0.3 eV > 2000 da kuma flux ≈1012 ph/s ta hanyar amfani da wani sinadari mai suna SX-700 wanda aka gyara tare da sinadari mai layi 1200 mm−1 na Si don gefen Fe 2p L2,3, Cr 2p L2,3, Ni 2p L2,3, da gefen Ce M4,5. Saboda haka, an kiyasta ƙudurin kuzarin beamline shine E/∆E = 700 eV/0.3 eV > 2000 da kuma flux ≈1012 ph/s ta hanyar amfani da wani ingantaccen SX-700 monochromator tare da Si 1200-line mm−1 grating don Fe 2p L2.3 edge, Cr 2p L2.3 edge, Ni 2p L2.3 edge, da Ce M4.5 edge. Таkym obrazom, эnergеtycheskoe razrешение knala chuchka bыlo otseneno kak E/∆E = 700 эВ/0,3 эВ> 2000 и 2000 и 2000 при использовании модифицированного монохроматора SX-700 с решеткой Si 1200 штрихов/мм для Fe кромать, L2,3, кромка Ni 2p L2,3 da кромка Ce M4,5. Saboda haka, an kiyasta ƙudurin kuzari na tashar hasken wutar lantarki kamar E/∆E = 700 eV/0.3 eV > 2000 da kuma kwararar iska ≈1012 f/s ta amfani da wani sinadari mai suna SX-700 da aka gyara tare da sinadari mai layi 1200/mm don gefen Fe 2p L2,3, gefen Cr 2p L2.3, gefen Ni 2p L2.3, da gefen Ce M4.5.因此，光束线能量分辨率估计为E/ΔE = 700 eV/0.3 eV > 2000 和通量≈1012 ph/s 通过使用0单色器和Si 1200 线mm−1 光栅用于 Fe 2p L2,3 边缘、Cr 2p L2,3 边缘、Ni 2p L2,3 边缘咘因此单色器 和 SI 1200 线 mm-1 光栅 于 Fe 2P 2P 2P L2.3 边缘、Cr 2p L2.3Saboda haka, lokacin amfani da na'urar monochromator ta SX-700 da aka gyara da kuma layin Si na 1200. 3, gefen Cr 2p L2.3, gefen Ni 2p L2.3 da gefen Ce M4.5.Faɗaɗa ƙarfin photon a cikin matakai 0.2 eV. A kowane kuzari, an yi rikodin hotunan PEEM ta amfani da na'urar gano TVIPS F-216 CMOS tare da haɗin fiber optic mai binning 2 x 2 wanda ke ba da pixels 1024 × 1024 a cikin filin gani na 20 µm. Lokacin fallasa hotunan shine daƙiƙa 0.2, matsakaicin firam 16. Ana zaɓar kuzarin hoton photoelectron ta yadda zai samar da matsakaicin siginar electron ta biyu. Ana yin duk ma'auni a daidai lokacin da hasken photon mai layi-layi ya nuna. Don ƙarin bayani game da ma'auni, duba wani bincike da ya gabata58. Bayan nazarin jimillar yawan amfanin electron (TEY)59 yanayin ganowa da aikace-aikacensa a cikin X-PEEM, an kiyasta zurfin gano wannan hanyar a ~4–5 nm don siginar Cr da ~6 nm don siginar Fe. Zurfin Cr yana kusa da kauri fim ɗin oxide (~4 nm)60,61 yayin da zurfin Fe ya fi kauri fim ɗin oxide girma. XAS da aka tara kusa da gefen Fe L cakuda ƙarfe oxide XAS da FeO ne daga matrix. A cikin yanayin farko, ƙarfin electrons da aka fitar ya faru ne saboda duk nau'ikan electrons da za su iya ba da gudummawa ga TEY. Duk da haka, siginar ƙarfe mai tsabta tana buƙatar ƙarin kuzarin motsi don electrons su ratsa ta cikin layin oxide, su isa saman, kuma mai nazarin ya tattara su. A wannan yanayin, siginar Fe0 galibi tana faruwa ne saboda LVV Auger electrons da electrons na biyu da suka fitar. Bugu da ƙari, ƙarfin TEY da waɗannan electrons suka bayar yana lalacewa a lokacin hanyar tserewa ta electron49 yana ƙara rage sa hannun Fe0 a cikin taswirar ƙarfe XAS.
Haɗa haƙar bayanai zuwa cikin ƙananan bayanai (bayanan X-PEEM) muhimmin mataki ne wajen fitar da bayanai masu dacewa (halayen sinadarai ko na zahiri) ta hanyar da yawa. Ana amfani da tarin bayanai na K sosai a fannoni da dama, ciki har da hangen nesa na na'ura, sarrafa hoto, gane tsari mara kulawa, basirar wucin gadi, da kuma nazarin rarrabuwa24. Misali, tarin bayanai na K yana da kyau wajen haɗa bayanai na hoton hyperspectral 62. A ƙa'ida, ga bayanai masu yawa, tsarin K-ma'ana zai iya haɗa su cikin sauƙi bisa ga bayanai game da halayensu (halayen makamashin photon). Tsarin K-ma'ana tsari ne na maimaitawa don raba bayanai zuwa ƙungiyoyin K marasa haɗuwa (ƙungiya), inda kowane pixel ya kasance cikin takamaiman rukuni dangane da rarrabawar sararin samaniya na rashin daidaituwar sinadarai a cikin tsarin ƙarfe. Tsarin K-ma'ana ya ƙunshi matakai biyu: mataki na farko yana ƙididdige centroids na K, kuma mataki na biyu yana sanya kowane batu ga rukuni tare da centroids maƙwabta. An bayyana tsakiyar nauyi na rukuni a matsayin ma'aunin lissafi na ma'aunin bayanai (XAS spectra) na wannan rukuni. Akwai nisan da za a ayyana centroids maƙwabta a matsayin nisan Euclidean. Don hoton shigarwa na px,y (x da y ƙuduri ne a cikin pixels), CK shine tsakiyar nauyi na rukuni; sannan za a iya raba wannan hoton (rukunin) zuwa ƙungiyoyin K ta amfani da K-means63. Matakan ƙarshe na tsarin tattarawa na K-means sune:
Mataki na 2. Lissafa matakin zama memba na dukkan pixels bisa ga centroid na yanzu. Misali, ana ƙididdige shi daga nisan Euclidean d tsakanin tsakiya da kowane pixel:
Mataki na 3 Sanya kowane pixel zuwa ga centroid mafi kusa. Sannan sake lissafin matsayin centroid na K kamar haka:
Mataki na 4. Maimaita tsarin (daidaitawa (7) da (8)) har sai centroids sun haɗu. Sakamakon ingancin rukuni na ƙarshe yana da alaƙa sosai da zaɓin centroids na farko63. Don tsarin bayanan PEEM na hotunan ƙarfe, yawanci X (x × y × λ) kubi ne na bayanan jeri na 3D, yayin da axes na x da y suna wakiltar bayanan sarari (ƙudurin pixel) kuma axis na λ ya dace da yanayin kuzarin spectral na photons. An yi amfani da algorithm na ma'anar K don bincika yankuna masu sha'awa a cikin bayanan X-PEEM ta hanyar raba pixels (clusters ko ƙananan tubalan) bisa ga halayen spectral ɗinsu da kuma cire mafi kyawun centroid (XAS spectral lanƙwasa) ga kowane mai nazari (cluster). Ana amfani da shi don nazarin rarraba sarari, canje-canjen spectral na gida, halayen oxidation da yanayin sinadarai. Misali, an yi amfani da algorithm na clustering na ma'anar K don yankunan Fe L-gefen da Cr L-gefen a cikin X-PEEM mai zafi da sanyi. An gwada adadi daban-daban na rukunin K (yankunan microstructural) don nemo mafi kyawun rukuni da centroids. Lokacin da aka nuna jadawalin, ana sake sanya pixels zuwa ga centroids ɗin cluster daidai. Kowace rarraba launi tana daidai da tsakiyar cluster, tana nuna tsarin sarari na abubuwa masu sinadarai ko na zahiri. centroids ɗin da aka cire haɗin layi ne na tsararren spectra.
Ana samun bayanai masu goyon bayan sakamakon wannan binciken daga marubucin WC bisa ga buƙata mai ma'ana.
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