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Intsimbi engagqwaliyo esetyenziswa kakhulu kunye neenguqulelo zayo ezenziweyo ziyamelana nokugqwala kwiimeko ezingqongileyo ngenxa yomaleko wokungashukumi oquka i-chromium oxide. Ukugqwala kunye nokukhukuliseka kwentsimbi ngokuqhelekileyo kunxulunyaniswa nokutshatyalaliswa kwezi layers, kodwa kunqabile kwinqanaba le-microscopic, kuxhomekeke kwimvelaphi yokungashukumi komphezulu. Kulo msebenzi, ukungafani kweekhemikhali zomphezulu we-nanoscale okufunyenwe yi-spectroscopic microscopy kunye nohlalutyo lwe-chemometric ngokungalindelekanga kulawula ukubola kunye nokugqwala kwe-cold rolled cerium modified super duplex stainless steel 2507 (SDSS) ngexesha lokuziphatha kwayo kokuguquguquka okushushu. kwelinye icala. Nangona i-X-ray photoelectron microscopy ibonise ukugubungela okufanayo komaleko wendalo we-Cr2O3, i-cold rolled SDSS ibonise iziphumo ezibi zokungashukumi ngenxa yokusasazwa kwendawo kwe-nanoislands ezityebileyo ze-Fe3+ kumaleko we-oxide we-Fe/Cr. Olu lwazi kwinqanaba le-athomu lubonelela ngokuqonda okunzulu kokugqwala kwentsimbi engagqwaliyo kwaye kulindeleke ukuba kuncede ekulweni nokugqwala kweentsimbi ezifanayo ezine-alloy ephezulu.
Ukususela oko kwaveliswa intsimbi engagqwaliyo, ukumelana nokugqwala kwee-alloys ze-ferrochromium kuye kwanxulunyaniswa ne-chromium, eyenza i-oxide/oxyhydroxide enamandla ebonisa ukuziphatha okungena kwi-passivating kwiindawo ezininzi. Xa kuthelekiswa neentsimbi ezingagqwaliyo zesiqhelo (i-austenitic kunye ne-ferritic), iintsimbi ezingagqwaliyo eziphezulu (SDSS) ezinokumelana nokugqwala okungcono zineempawu zoomatshini eziphezulu1,2,3. Amandla oomatshini akhulayo avumela uyilo olukhaphukhaphu noluncinci. Ngokwahlukileyo koko, i-SDSS enoqoqosho inokumelana okuphezulu nokugqwala kwemingxuma kunye ne-crevice, nto leyo ebangela ubomi benkonzo obude kunye nokusetyenziswa okubanzi kulawulo longcoliseko, izikhongozeli zeekhemikhali, kunye nomzi-mveliso weoyile negesi ongaselunxwemeni4. Nangona kunjalo, uluhlu oluncinci lwamaqondo obushushu onyango lobushushu kunye nokwenziwa kakubi kuyayithintela indlela esetyenziswa ngayo ngokubanzi. Ke ngoko, i-SDSS itshintshiwe ukuphucula ezi mpawu zingasentla. Umzekelo, ukuguqulwa kwe-Ce kunye nokongezwa okuphezulu kwe-N 6, 7, 8 kwaziswa kwi-2507 SDSS (Ce-2507). Uxinzelelo olufanelekileyo lwe-0.08 wt.% rare earth element (Ce) lunefuthe elihle kwiimpawu zoomatshini ze-DSS, njengoko luphucula ukucocwa kweenkozo kunye namandla omda weenkozo. Ukumelana nokuguguleka nokubola, amandla okutsalwa kunye namandla okuvelisa, kunye nokusebenza ngobushushu nazo ziphuculwe9. Inani elikhulu le-nitrogen lingathatha indawo yomxholo we-nickel obizayo, okwenza i-SDSS ibe nexabiso eliphantsi10.
Kutshanje, i-SDSS iguqulwe ngokweplastiki kubushushu obahlukeneyo (ubushushu obuphantsi, obubandayo nobushushu) ukuze kufezekiswe iipropati ezintle kakhulu zoomatshini6,7,8. Nangona kunjalo, ukumelana nokugqwala okugqwesileyo kwe-SDSS kungenxa yokubakho kwefilimu encinci ye-oxide kumphezulu, echaphazeleka zizinto ezininzi, ezinje ngokubakho kwezigaba ezininzi ezinemida eyahlukeneyo yeenkozo, iiprecipitates ezingafunekiyo kunye neempendulo ezahlukeneyo. isakhiwo sangaphakathi esingahambelaniyo sezigaba ezahlukeneyo ze-austenitic kunye ne-ferritic siguqulwe 7. Ke ngoko, uphononongo lweepropati ze-microdomain zeefilimu ezinjalo kwinqanaba lesakhiwo se-elektroniki lubaluleke kakhulu ekuqondeni ukugqwala kwe-SDSS kwaye lufuna iindlela ezintsonkothileyo zovavanyo. Okwangoku, iindlela ezinobuthathaka kumphezulu ezifana ne-Auger electron spectroscopy11 kunye ne-X-ray photoelectron spectroscopy12,13,14,15 kunye nenkqubo ye-X-ray photoelectron photoelectron eqinileyo ziyahlula, kodwa zihlala zisilela ukwahlula, iimeko zeekhemikhali zento enye kwiindawo ezahlukeneyo kwindawo kwi-nanoscale. Izifundo ezininzi zakutshanje zidibanise i-oxidation ye-chromium yendawo kunye nokuziphatha kokugqwala okubonweyo kwee-steels ze-austenitic ezingagqwali ezili-17, ii-steels ze-martensitic ezingagqwali ezili-18, kunye ne-SDSS 19, 20. Nangona kunjalo, ezi zifundo zigxile kakhulu kwisiphumo se-Cr heterogeneity (umz., imeko ye-oxidation ye-Cr3+) ekuchaseni ukugqwala. Ukungafani kwe-lateral kwiimeko ze-oxidation zezinto kunokubangelwa ziikhompawundi ezahlukeneyo ezinee-elements ezifanayo, njenge-iron oxides. Ezi khompawundi zizuza ubungakanani obuncinci obucutshungulwa ngokushisa obusondeleleneyo, kodwa zahlukile kwi-composition kunye ne-oxidation state16,21. Ke ngoko, ukutyhila ukutshatyalaliswa kweefilimu ze-oxide kunye ne-pitting kufuna ukuqonda ukungalingani komphezulu kwinqanaba le-microscopic. Ngaphandle kwezi mfuno, uvavanyo lobungakanani olufana nokungafani kwe-oxidation ecaleni, ingakumbi i-iron kwisikali se-nano/atomic, lusanqongophala kwaye ukubaluleka kwazo kokuchasana nokugqwala akukahlolwa. Kude kube kutshanje, imeko yeekhemikhali yezinto ezahlukeneyo, ezifana neFe kunye neCa, yayichazwa ngokwenani kwiisampuli zentsimbi kusetyenziswa i-soft X-ray photoelectron microscopy (X-PEEM) kwiindawo zokukhanya ze-synchrotron ze-nanoscale. Idityaniswe neendlela ze-X-ray absorption spectroscopy (XAS) ezibuthathaka kwiikhemikhali, i-X-PEEM ivumela ukulinganiswa kwe-XAS ngesisombululo esiphezulu sendawo kunye ne-spectral, inika ulwazi lweekhemikhali malunga nokwakheka kwezinto kunye nesimo sayo sekhemikhali ngesisombululo sendawo ukuya kuthi ga kwisikali se-nanometer 23. Olu qwalaselo lwe-spectroscopic lwendawo yokuqalisa phantsi kwe-microscope lunceda uvavanyo lweekhemikhali zasekuhlaleni kwaye lunokubonisa ngokwendawo utshintsho lweekhemikhali olungakhange luhlolwe ngaphambili kumaleko we-Fe.
Olu phononongo lwandisa iingenelo ze-PEEM ekufumaneni umahluko kwiikhemikhali kwi-nanoscale kwaye lubonisa indlela yohlalutyo lomphezulu we-atomic eqondakalayo yokuqonda ukuziphatha kokugqwala kwe-Ce-2507. Isebenzisa i-K-means cluster chemometric data24 ukumakisha ulwakhiwo lweekhemikhali zehlabathi (ukungafani) kwezinto ezibandakanyekayo, kunye neemeko zazo zeekhemikhali eziboniswe kwisimo sezibalo. Ngokungafaniyo nemeko yendabuko yokugqwala okubangelwa kukuqhekeka kwefilimu ye-chromium oxide, ukungakwazi ukuhamba kakuhle kwangoku kunye nokuxhathisa ukugqwala okubi kubangelwa ziziqithi ze-nanoislands ze-Fe3+ ezityebileyo kufutshane nomaleko we-oxide we-Fe/Cr, onokuba ngumphumo wee-oxides ezikhuselayo. Endaweni yokuqhekeka, kwenziwa ifilimu ebangela ukugqwala.
Ukuziphatha okukonakalisayo kwe-SDSS 2507 ekhubazekileyo kwaqala kwavavanywa kusetyenziswa imilinganiselo ye-electrochemical. Kumfanekiso 1 ubonisa ii-curves ze-Nyquist kunye ne-Bode zeesampuli ezikhethiweyo kwizisombululo zamanzi ze-acidic (pH = 1) ze-FeCl3 kubushushu begumbi. I-electrolyte ekhethiweyo isebenza njenge-arhente enamandla ye-oxidizing, ebonisa ukuthambekela kwefilimu yokuchithakala. Nangona izinto azizange zidlule kwi-pitting yobushushu begumbi ezinzileyo, olu hlalutyo lubonelele ngeziganeko zokungaphumeleli ezinokubakho kunye neenkqubo zasemva kokubola. Isekethe elinganayo (Umfanekiso 1d) yasetyenziselwa ukulingana ne-spectra ye-electrochemical impedance spectroscopy (EIS), kwaye iziphumo zokulingana ezihambelanayo ziboniswe kwiTheyibhile 1. Izangqa ezipheleleyo zesiqingatha zavela xa kuvavanywa iisampulu eziphathweyo zesisombululo kunye nezishushu, ngelixa izangqa ezixineneyo zesiqingatha zaziqengqeleka ngokubandayo (Umfanekiso 1b). Kwi-spectrum ye-EIS, i-radius ye-semicircle ingathathwa njenge-polarization resistance (Rp)25,26. I-Rp yesisombululo se-SDSS esiphathwe kwiTheyibhile 1 imalunga ne-135 kΩ cm-2, nangona kunjalo kwi-SDSS eshushu necoliweyo eqhotsiweyo sinokubona amaxabiso aphantsi kakhulu angama-34.7 kunye nama-2.1 kΩ cm–2 ngokwahlukeneyo. Oku kuncipha okukhulu kwi-Rp kubonisa isiphumo esibi sokuguqulwa kweplastiki kwi-passivation kunye nokumelana nokugqwala, njengoko kubonisiwe kwiingxelo zangaphambili 27, 28, 29, 30.
i-Nyquist, b, c I-Bode impedance kunye ne-phase diagrams, kunye ne-equivalent circuit model ye-d, apho i-RS i-electrolyte resistance, i-Rp i-polarization resistance, kwaye i-QCPE yi-constant phase element oxide esetyenziselwa ukulinganisa i-non-ideal capacitance (n). Ukulinganiswa kwe-EIS kwenziwe nge-no-load potential.
Ii-constants zokuqala zomyalelo ziboniswe kwi-Bode diagram kwaye i-high frequency plateau imele ukumelana kwe-electrolyte RS26. Njengoko i-frequency iyancipha, i-impedance iyanda kwaye kufunyenwe i-negative phase angle, ebonisa ukuba i-capacitance dominance inamandla. I-phase angle iyanda, igcina ixabiso layo eliphezulu kuluhlu olubanzi lwee-frequency, ize inciphe (Umzobo 1c). Nangona kunjalo, kuzo zonke iimeko ezintathu eli xabiso liphezulu lisengaphantsi kwe-90°, libonisa ukuziphatha kwe-capacitive okungekuhle ngenxa yokusasazwa kwe-capacitive. Ke ngoko, i-QCPE constant phase element (CPE) isetyenziselwa ukumela ukusasazwa kwe-interfacial capacitance okuvela kwi-surface roughness okanye i-inhomogeneity, ngakumbi ngokwe-atomic scale, i-fractal geometry, i-electrode porosity, i-non-uniform potential, kunye nokusasazwa kwe-surface dependent current. I-Electrode geometry31,32. I-CPE impedance:
apho u-j linani elicingelwayo kwaye u-ω liyi-angular frequency. I-QCPE yi-frequency independent constant ehambelana nendawo evulekileyo esebenzayo ye-electrolyte. I-n linani lamandla elingenamlinganiselo elichaza ukuphambuka kwindlela efanelekileyo yokusebenza kwe-capacitor, oko kukuthi, xa u-n esondele ku-1, i-CPE isondele ku-capacitance emsulwa, kwaye ukuba u-n usondele ku-zero, yi-resistance. Ukuphambuka okuncinci kwe-n, kufutshane no-1, kubonisa indlela yokuziphatha engafanelekanga yomphezulu emva kovavanyo lwe-polarization. I-QCPE ye-cold rolled SDSS iphezulu kakhulu kuneemveliso ezifanayo, oko kuthetha ukuba umgangatho womphezulu awufani kangako.
Ngokuhambelana neempawu ezininzi zokuxhathisa ukugqwala kweentsimbi ezingenanto, umxholo ophezulu we-Cr we-SDSS ngokubanzi uphumela ekuchaseni okuphezulu kokugqwala kwe-SDSS ngenxa yokubakho kwefilimu ye-oxide ekhuselayo engashukumiyo kumphezulu17. Le filimu yokuthambisa idla ngokuba ne-Cr3+ oxides kunye/okanye ii-hydroxides, ikakhulu idibanisa ii-Fe2+, ii-Fe3+ oxides kunye/okanye ii-(oxy) hydroxides 33. Nangona umphezulu ofanayo ufana, umaleko we-oxide yokuthambisa, kwaye akukho kuqhekeka okubonakalayo kumphezulu, njengoko kumiselwe yimifanekiso emincinci,6,7 ukuziphatha kokugqwala kwe-SDSS esebenza ngobushushu kunye ne-cold-rolled kwahlukile kwaye ke ngoko kufuna uphando olunzulu lwe-deformation microstructure kunye neempawu zesakhiwo sentsimbi.
Ulwakhiwo lwe-microstructure yentsimbi engagqwaliyo eguquliweyo luphandwe ngobuninzi kusetyenziswa ii-X-rays zangaphakathi kunye nee-synchrotron ezinamandla aphezulu (Imifanekiso eyongezelelweyo 1, 2). Uhlalutyo oluneenkcukacha lubonelelwe kwiNkcukacha eyoNgezelelweyo. Nangona oku kuhambelana kakhulu nohlobo lwesigaba esiphambili, umahluko ufunyenwe kwiinxalenye zevolumu zezigaba, ezidweliswe kwiTheyibhile eyoNgezelelweyo 1. Umahluko ungabangelwa yi-heterogeneous phase fraction kumphezulu kunye ne-volume fraction (XRD) phantsi kobunzulu obahlukeneyo bokufunyanwa ngokusebenzisa i-X-ray diffraction kunye nemithombo eyahlukeneyo yamandla e-incident photons. Inani eliphezulu le-austenite kwiisampuli ezigoqiweyo ezibandayo, ezimiselwe yi-XRD evela kumthombo webhubhoratri, zibonisa ukudlula okungcono kunye nokumelana nokugqwala okungcono emva koko35, ngelixa iziphumo ezichanekileyo nezineenkcukacha zibonisa iindlela ezichaseneyo kumlinganiselo wesigaba. Ukongeza, ukumelana nokugqwala kwentsimbi kuxhomekeke kwinqanaba lokucocwa kwengqolowa, ukunciphisa ubungakanani bengqolowa, ukwanda kwe-microdeformations kunye noxinano lwe-dislocation olwenzeka ngexesha lonyango lwe-thermomechanical36,37,38. Iisampuli ezishushu zibonisa uhlobo olunezinti, olubonisa iinkozo ezinobukhulu be-micron, ngelixa iiringi ezigudileyo ezibonwe kwiisampuli ezigoqwe ngokubandayo (Umzobo Ongezelelweyo 3) zibonisa ukucocwa okubalulekileyo kweenkozo kwi-nanoscale kumsebenzi wangaphambili6, ekufuneka ifake isandla ekuphuhlisweni kwefilimu kunye nokwanda kokumelana nokugqwala. Uxinano oluphezulu lwe-dislocation ludla ngokunxulunyaniswa nokumelana okuphantsi kwi-pitting, okuhambelana kakuhle nomlinganiselo we-electrochemical.
Utshintsho kwiimeko zeekhemikhali ze-microdomains zezinto ezisisiseko luye lwafundwa ngokucwangcisiweyo kusetyenziswa i-X-PEEM. Nangona kukho ubuninzi bezinto ezidibanisayo, i-Cr, i-Fe, i-Ni, kunye ne-Ce39 zikhethwe apha kuba i-Cr yeyona nto iphambili ekwakhiweni kwefilimu yokudlulisa amandla, i-Fe yeyona nto iphambili kwintsimbi, kwaye i-Ni iphucula ukudlulisa amandla kwaye ilinganisela isakhiwo sesigaba se-ferrite-austenitic kunye nenjongo yokuguqula i-Ce. Ngokulungisa amandla emitha ye-synchrotron, i-RAS yagqunywa ukusuka kumphezulu ngeempawu eziphambili ze-Cr (umphetho L2.3), i-Fe (umphetho L2.3), i-Ni (umphetho L2.3) kunye ne-Ce (umphetho M4.5). ukwakheka okushushu kunye nokuqengqeleka okubandayo kwe-Ce-2507 SDSS. Uhlalutyo lwedatha olufanelekileyo lwenziwe ngokubandakanya ukulinganiswa kwamandla kunye nedatha epapashwe (umz. i-XAS 40, 41 kwi-Fe L2, imiphetho emi-3).
Kumfanekiso 2 ubonisa imifanekiso ye-X-PEEM ye-hot-worked (Umfanekiso 2a) kunye ne-cold-rolled (Umfanekiso 2d) Ce-2507 SDSS kunye nemiphetho ye-XAS ehambelanayo ye-Cr kunye ne-Fe L2,3 kwiindawo eziphawulwe ngokwahlukeneyo. Umphetho we-L2,3 we-XAS uphonononga i-3d states engabanjwanga emva kwe-electron photoexcitation kumanqanaba okwahlulahlula i-spin-orbit 2p3/2 (umphetho we-L3) kunye ne-2p1/2 (umphetho we-L2). Ulwazi malunga nemeko ye-valence ye-Cr lufunyenwe kwi-XAS kumphetho we-L2,3 kumfanekiso 2b, e. Uthelekiso neejaji. I-42,43 ibonise ukuba iincopho ezine zibonwe kufutshane nomphetho we-L3, ezibizwa ngokuba yi-A (578.3 eV), B (579.5 eV), C (580.4 eV) kunye ne-D (582.2 eV), zibonisa i-octahedral Cr3+, ehambelana ne-Cr2O3 ion. Iispectra zovavanyo ziyavumelana nezibalo zethiyori eziboniswe kwiiphaneli b kunye no-e, ezifunyenwe kwiibalo ezininzi zentsimi yekristale kwi-interface yeCr L2.3 kusetyenziswa intsimi yekristale ye-2.0 eV44. Zombini iindawo ze-SDSS ezisebenza ngobushushu kunye neziqengqelekayo ezibandayo zigqunywe ngomaleko ofanayo weCr2O3.
umfanekiso wobushushu we-X-PEEM we-SDSS eguqulwe ngobushushu ohambelana ne-b Cr L2.3 edge kunye ne-c Fe L2.3 edge, d Umfanekiso wobushushu we-X-PEEM we-SDSS eqengqelekayo ebandayo ohambelana ne-e Cr L2.3 edge kunye ne-f Fe L2 .3 edge side (f). Ii-XAS spectra zidwetshwe kwiindawo ezahlukeneyo zesithuba eziphawulwe kwimifanekiso yobushushu (a, d), imigca e-orenji enamachaphaza ku-(b) kunye no-(e) imele ii-XAS spectra ezilinganisiweyo ze-Cr3+ ezinexabiso le-crystal field le-2.0 eV. Kwimifanekiso ye-X-PEEM, sebenzisa i-palette yobushushu ukuphucula ukufundeka komfanekiso, apho imibala ukusuka kuluhlaza okwesibhakabhaka ukuya kubomvu ihambelana nobukhulu bokufunxwa kwe-X-ray (ukusuka ezantsi ukuya phezulu).
Nokuba imeko-bume yeekhemikhali zezi zinto zesinyithi injani na, imeko yeekhemikhali yokongezwa kwezinto ze-Ni kunye ne-Ce kwiisampulu zombini ayizange itshintshe. Umzobo owongezelelweyo. Imifanekiso 5-9 ibonisa imifanekiso ye-X-PEEM kunye nee-spectra ze-XAS ezihambelanayo ze-Ni kunye ne-Ce kwiindawo ezahlukeneyo kumphezulu weesampuli ezishushu neziqengqelekayo. I-Ni XAS ibonisa imeko ye-oxidation ye-Ni2+ phezu komphezulu wonke olinganisiweyo weesampuli ezishushu neziqengqelekayo (Ingxoxo Eyongezelelekileyo). Kufuneka kuqatshelwe ukuba, kwimeko yeesampuli ezishushu, isignali ye-XAS ye-Ce ayizange ibonwe, ngelixa kwimeko yeesampuli eziqengqelekayo ezibandayo, i-spectrum ye-Ce3+ yabonwa. Ukubonwa kwamabala e-Ce kwiisampulu eziqhaqhelekayo ezibandayo kubonise ukuba i-Ce ibonakala ikakhulu ngohlobo lwe-precipitates.
Kwi-SDSS eguqulwe bubushushu, akukho tshintsho lwesakhiwo sendawo kwi-XAS kumda we-Fe L2,3 olubonwe (Umzobo 2c). Nangona kunjalo, i-Fe matrix micro-regionally itshintsha imeko yayo yekhemikhali kwiindawo ezisixhenxe ezikhethwe ngokungacwangciswanga ze-SDSS eqhotsiweyo ebandayo, njengoko kubonisiwe kwi-Fig. 2f. Ukongeza, ukuze kufunyanwe umbono ochanekileyo wotshintsho kwimeko ye-Fe kwiindawo ezikhethiweyo kwi-Fig. 2f, kwenziwe izifundo zomphezulu wendawo (Umzobo 3 kunye nomzobo ongezelelweyo 10) apho kukhethwe khona iindawo ezincinci ezijikelezayo. Ii-XAS spectra zomda we-Fe L2,3 weenkqubo ze-α-Fe2O3 kunye ne-Fe2+ octahedral oxides zenziwe imodeli ngokubalwa kwe-crystal field ezininzi kusetyenziswa amasimi ekristale e-1.0 (Fe2+) kunye ne-1.0 (Fe3+)44. Siqaphela ukuba i-α-Fe2O3 kunye ne-γ-Fe2O3 zine-symmetries zasekuhlaleni ezahlukeneyo45,46, i-Fe3O4 inomdibaniso we-Fe2+ kunye ne-Fe3+,47, kunye ne-FeO45 njenge-Fe2+ oxide edityanisiweyo ngokusemthethweni (3d6). Siqaphela ukuba i-α-Fe2O3 kunye ne-γ-Fe2O3 zine-symmetries zasekuhlaleni ezahlukeneyo45,46, i-Fe3O4 inomdibaniso we-Fe2+ kunye ne-Fe3+,47, kunye ne-FeO45 njenge-Fe2+ oxide edityanisiweyo ngokusemthethweni (3d6).Qaphela ukuba i-α-Fe2O3 kunye ne-γ-Fe2O3 zine-symmetries zasekuhlaleni ezahlukeneyo45,46, i-Fe3O4 idibanisa zombini i-Fe2+ kunye ne-Fe3+,47 kunye ne-FeO45 ngendlela ye-oxide edivalent esemthethweni i-Fe2+ (3d6).Qaphela ukuba i-α-Fe2O3 kunye ne-γ-Fe2O3 zine-symmetries zasekuhlaleni ezahlukeneyo45,46, i-Fe3O4 inomdibaniso we-Fe2+ kunye ne-Fe3+,47 kwaye i-FeO45 isebenza njenge-oxide ye-Fe2+ esemthethweni (3d6). Zonke ii-ion ze-Fe3+ kwi-α-Fe2O3 zinezikhundla ze-Oh kuphela, ngelixa i-γ-Fe2O3 idla ngokumelwa yi-Fe3+ t2g [Fe3+5/3V1/3]eg O4 spinel enezithuba kwiindawo umz. Ke ngoko, ii-ion ze-Fe3+ kwi-γ-Fe2O3 zinezikhundla ze-Td kunye ne-Oh. Njengoko kukhankanyiwe kwiphepha elidlulileyo,45 nangona umlinganiselo wobunzulu bezi zimbini wahlukile, umlinganiselo wazo wobunzulu umz/t2g yi-≈1, ngelixa kule meko umlinganiselo wobunzulu obonweyo umz/t2g umalunga ne-1. Oku kususa ithuba lokuba kwimeko yangoku kuphela yi-Fe3+ ekhoyo. Xa sijonga imeko ye-Fe3O4 kunye ne-Fe2+ kunye ne-Fe3+, uphawu lokuqala, olwaziwa ngokuba nomphetho we-L3 obuthathaka (onamandla) kwi-Fe, lubonisa inani elincinci (elikhulu) le-t2g engenanto. Oku kusebenza kwi-Fe2+ (Fe3+), ebonisa ukuba uphawu lokuqala lokunyuka lubonisa ukwanda komxholo we-Fe2+47. Ezi ziphumo zibonisa ukuba ukuhlala kunye kwe-Fe2+ kunye ne-γ-Fe2O3, i-α-Fe2O3 kunye/okanye i-Fe3O4 kulawula kumphezulu obandayo we-composites.
Imifanekiso yomfanekiso we-photoelectron thermal eyandisiweyo ye-XAS spectra (a, c) kunye (b, d) enqumla umda we-Fe L2,3 kwiindawo ezahlukeneyo zesithuba ngaphakathi kwemimandla ekhethiweyo yesi-2 kunye ne-E kwiMifanekiso yesi-2d.
Idatha yovavanyo efunyenweyo (Umzobo 4a kunye nomzobo ongezelelweyo 11) idwetshwe kwaye ithelekiswa nedatha yeekhompawundi ezicocekileyo 40, 41, 48. Iintlobo ezintathu ezahlukeneyo ze-Fe L-edge XAS spectra ebonwe ngovavanyo (XAS-1, XAS-2 kunye ne-XAS-3: Umzobo 4a). Ngokukodwa, i-spectrum 2-a (ebizwa ngokuba yi-XAS-1) kwi-Fig. 3b elandelwa yi-spectrum 2-b (ebhalwe yi-XAS-2) ibonwe kuyo yonke indawo yokufumanisa, ngelixa ii-spectra ezifana ne-E-3 zibonwe kumfanekiso 3d (ebhalwe yi-XAS-3) zibonwe kwiindawo ezithile. Njengomthetho, iiparameter ezine zisetyenzisiwe ukuchonga imeko ye-valence ekhoyo kwisampulu efundwayo: (1) iimpawu ze-spectral L3 kunye ne-L2, (2) izikhundla zamandla zeempawu ze-L3 kunye ne-L2, (3) umahluko wamandla L3-L2. , (4) umlinganiselo wobunzulu be-L2/L3. Ngokwezinto ezibonwayo (Umzobo 4a), zonke izinto ezintathu ze-Fe, ezizezi, i-Fe0, i-Fe2+, kunye ne-Fe3+, zikhona kumphezulu we-SDSS ophantsi kophando. Umlinganiselo wokubala intensity L2/L3 ukwabonise ukuba zikhona zonke izinto ezintathu.
i-spectra ye-XAS elinganisiweyo ye-Fe enedatha ezintathu ezahlukeneyo zovavanyo ezibonisiweyo (imigca eqinileyo i-XAS-1, i-XAS-2 kunye ne-XAS-3 ihambelana ne-2-a, i-2-b kunye ne-E-3 kwiFig. 2 kunye ne-3) Uthelekiso , ii-Octahedrons Fe2+, i-Fe3+ kunye namaxabiso e-crystal field ye-1.0 eV kunye ne-1.5 eV, ngokulandelelana, idatha yovavanyo elinganiswe nge-bd (XAS-1, XAS-2, XAS-3) kunye nedatha ye-LCF ehambelanayo (umgca omnyama oqinileyo), kwaye nakwimo ye-XAS-3 spectra ene-Fe3O4 (imeko exutyiweyo ye-Fe) kunye nemigangatho ye-Fe2O3 (i-Fe3+ ecocekileyo).
Ukulingana komxube othe ngqo (LCF) wemigangatho emithathu 40, 41, 48 kusetyenzisiwe ukulinganisa ukwakheka kwe-iron oxide. I-LCF yenziwe kwiispectra ezintathu ze-Fe L-edge XAS ezikhethiweyo ezibonisa umahluko ophezulu, oko kukuthi i-XAS-1, i-XAS-2 kunye ne-XAS-3, njengoko kubonisiwe kwiFig. 4b–d. Kwi-LCF fittings, i-10% Fe0 ithathelwe ingqalelo kuzo zonke iimeko ngenxa yokuba sibone i-ledge encinci kuyo yonke idatha, kwaye ngenxa yokuba i-metallic iron yeyona nto iphambili kwintsimbi. Enyanisweni, ubunzulu bovavanyo lwe-X-PEEM ye-Fe (~6 nm)49 bukhulu kunobukhulu obuqikelelweyo beleyara ye-oxidation (kancinci > 4 nm), okuvumela ukubonwa kwesiginali evela kwi-iron matrix (Fe0) phantsi kweleyara ye-passivation. Enyanisweni, ubunzulu bovavanyo lwe-X-PEEM ye-Fe (~6 nm)49 bukhulu kunobukhulu obuqikelelweyo beleyara ye-oxidation (kancinci > 4 nm), okuvumela ukubonwa kwesiginali evela kwi-iron matrix (Fe0) phantsi kweleyara ye-passivation. Действительно, пробная глубина X-PEEM для Fe (~ 6 нм)49 больше, чем предполагаемая толщина слоя окисления (немного > 4 iintsini), сигнал от железной матрицы (Fe0) под пассивирующим слоем. Enyanisweni, ubunzulu be-probe X-PEEM kwi-Fe (~6 nm)49 bukhulu kunobukhulu obuqikelelweyo beleyara ye-oxidation (kancinci >4 nm), nto leyo eyenza kube nokwenzeka ukubona isignali evela kwi-iron matrix (Fe0) phantsi kweleyara ye-passivation.事实上， X-PEEM 对Fe（~6 nm）49的检测深度大于估计的氧化层厚度（略> 4 nm），允许检测來自钝化层下方的铁基体（Fe0）的信号。事实上 , X-PEEM 对 Fe （~ 6 nm） 49 的 检测 深度 大于 的 氧化层 厚度 略 略> 4 nm） 允杀 4 nm） 允杀下方 铁基体 （fe0） 的。Фактически, глубина обнаружения Fe (~ 6 нм) 49 с помощью X-PEEM больше, чем предполагаемая толщина оксидного слоя (немного > 4 обнаруживать сигнал от железной матрицы (Fe0) ниже пассивирующего слоя. Enyanisweni, ubunzulu bokufunyanwa kwe-Fe (~6 nm) 49 yi-X-PEEM bukhulu kunobukhulu obulindelekileyo bomaleko we-oxide (kancinci > 4 nm), okuvumela ukufunyanwa kwesignali evela kwi-iron matrix (Fe0) ngaphantsi komaleko we-passivation. .Kwenziwe imidibaniso eyahlukeneyo yeFe2+ kunye neFe3+ ukuze kufunyanwe isisombululo esifanelekileyo sedatha yovavanyo ebonweyo. Kumfanekiso 4b ubonisa i-XAS-1 spectrum yokudibanisa iFe2+ kunye neFe3+, apho iinxalenye zeFe2+ kunye neFe3+ zazifana malunga ne-45%, zibonisa iimeko ezixutyiweyo ze-oxidation zeFe. Ngelixa kwi-XAS-2 spectrum, ipesenti yeFe2+ kunye neFe3+ iba yi ~30% kunye ne-60%, ngokulandelelana. IFe2+ ​​ingaphantsi kweFe3+. Umlinganiselo weFe2+ ukuya kwiFe3, olingana ne-1:2, uthetha ukuba iFe3O4 inokwakheka ngomlinganiselo ofanayo phakathi kwee-ion zeFe. Ukongeza, kwi-XAS-3 spectrum, ipesenti yeFe2+ kunye neFe3+ iba yi ~10% kunye ne-80%, nto leyo ebonisa ukuguqulwa okuphezulu kweFe2+ ukuya kwiFe3+. Njengoko kukhankanyiwe ngasentla, iFe3+ ingavela kwi-α-Fe2O3, γ-Fe2O3 okanye iFe3O4. Ukuze kuqondwe umthombo onokwenzeka weFe3+, i-XAS-3 spectrum idwetshwe ngemigangatho eyahlukeneyo yeFe3+ kuMfanekiso 4e, nto leyo ebonisa ukufana nemigangatho yomibini xa kujongwa incochoyi ye-B. Nangona kunjalo, ubunzulu beencochoyi zamagxa (A: ukusuka kwiFe2+) kunye nomlinganiselo wobunzulu be-B/A bubonisa ukuba i-spectrum ye-XAS-3 isondelelene, kodwa ayihambelani ne-spectrum ye-γ-Fe2O3. Xa kuthelekiswa ne-bulk γ-Fe2O3, incochoyi ye-Fe 2p XAS ye-A SDSS inobunzulu obuphezulu kancinci (Umzobo 4e), nto leyo ebonisa ubunzulu obuphezulu be-Fe2+. Nangona i-spectrum ye-XAS-3 ifana ne-γ-Fe2O3, apho i-Fe3+ ikhona kwiindawo ze-Oh kunye ne-Td, ukuchongwa kweemeko ezahlukeneyo ze-valence kunye nokulungelelaniswa kuphela ecaleni komda we-L2,3 okanye umlinganiselo wobunzulu be-L2/L3 kusaqhubeka kuyingxaki. Isihloko sengxoxo eqhubekayo ngenxa yobunzima bezinto ezahlukeneyo ezichaphazela i-spectrum yokugqibela41.
Ukongeza kumahluko we-spectral kwimeko yekhemikhali yemimandla ekhethiweyo enomdla echazwe apha ngasentla, ukungafani kweekhemikhali zehlabathi jikelele kwezinto eziphambili i-Cr kunye ne-Fe kuhlolwe ngokuhlela zonke ii-spectra ze-XAS ezifunyenwe kumphezulu wesampuli kusetyenziswa indlela ye-K-means clustering. . Iiprofayili ze-Edge Cr L zimiselwe ukwenza amaqela amabini afanelekileyo asasazwe ngokwendawo kwiisampulu ezishushu nezibandayo eziboniswe kwiMifanekiso 5. Kuyacaca ukuba akukho tshintsho lwesakhiwo sendawo olubonwa lufana, kuba ii-centroid ezimbini ze-XAS Cr spectra ziyafana. Ezi mpawu ze-spectral zamaqela amabini ziphantse zifane nezo zihambelana ne-Cr2O342, oko kuthetha ukuba iileya ze-Cr2O3 zibekwe ngokulinganayo kwi-SDSS.
I-Cr L K-means edge region clusters, kwaye i-b yi-XAS centroids ehambelanayo. Iziphumo zothelekiso lwe-K-means X-PEEM lwe-SDSS eqhotsiweyo ebandayo: c I-Cr L2.3 edge region ye-K-means clusters kunye ne-d ehambelanayo ne-XAS centroids.
Ukubonisa iimaphu zomphetho we-FeL ezintsonkothileyo, amaqela amane nantlanu alungiselelweyo kunye nee-centroids zawo ezinxulumene nazo (iiprofayili ze-spectral) zisetyenzisiwe kwiisampuli ezishushu neziqengqelekayo, ngokulandelelana. Ke ngoko, ipesenti (%) ye-Fe2+ kunye ne-Fe3+ ingafunyanwa ngokufaka i-LCF eboniswe kwiFig.4. I-pseudo potential ye-Epseudo njengomsebenzi we-Fe0 isetyenzisiwe ukutyhila ukungalingani kwe-microchemical yefilimu ye-oxide yomphezulu. I-Epseudo iqikelelwa ngomgaqo wokuxuba,
apho \(\rm{E}_{\rm{Fe}/\rm{Fe}^{2 + (3 + )}}\) ilingana \(\rm{Fe} + 2e^ – \ ukuya ku \rm {Fe}^{2 + (3 + )}\), 0.440 kunye no-0.036 V, ngokwahlukeneyo. Iingingqi ezine-potential ephantsi zinomxholo ophezulu we-Fe3+ compound. Ukusasazwa kwe-potential kwiisampuli eziguqulwe ngobushushu kunophawu oluneeleya ezinotshintsho olukhulu olumalunga ne-0.119 V (Umzobo 6a, b). Olu sasazo lwe-potential lunxulumene ngokusondeleyo ne-surface topography (Umzobo 6a). Akukho tshintsho luxhomekeke kwisikhundla kwi-laminar yangaphakathi engaphantsi olubonwe (Umzobo 6b). Ngokuchaseneyo, ngokudityaniswa kwee-oxides ezahlukeneyo kunye nomxholo owahlukileyo we-Fe2+ kunye ne-Fe3+ kwi-SDSS eqhotsiweyo ebandayo, umntu unokubona uhlobo olungafaniyo lwe-pseudopotential (Umzobo 6c, d). Ii-Fe3+ oxides kunye/okanye ii-oxy hydroxides zezona zinto ziphambili zokugqwala kwintsimbi kwaye zingena kwioksijini namanzi50. Kule meko, iziqithi ezityebileyo kwiFe3+ zithathwa njengezisasazeke kwindawo kwaye zinokuthathwa njengeendawo ezigqwalileyo. Kwangaxeshanye, i-gradient kwintsimi enokubakho, endaweni yexabiso elipheleleyo le-potential, ingasetyenziswa njengesalathiso sendawo yeendawo ezigqwalileyo ezisebenzayo. Olu sasazo lungalinganiyo lweFe2+ kunye neFe3+ kumphezulu we-SDSS eqhotsiweyo ebandayo lunokutshintsha ikhemistri yendawo kwaye lubonelele ngendawo esebenzayo ngakumbi ekuqhekekeni kwefilimu ye-oxide kunye neempendulo zokugqwala, ngaloo ndlela luvumela ukugqwala okuqhubekayo kwe-matrix yesinyithi engaphantsi, okubangela ukugqwala kwangaphakathi. ukungafani kweempawu kunye nokuncipha kweempawu zokukhusela zomaleko odlulayo.
Ii-K-means clusters kunye nee-XAS centroids ezihambelanayo kummandla we-Fe L2.3 edge we-hot-deformed X-PEEM ac kunye ne-df ye-cold-rolled SDSS. a, d Ii-K-means cluster plots ezigqunywe kwimifanekiso ye-X-PEEM. I-pseudo potential ebaliweyo (i-Epseudo) ikhankanyiwe kunye ne-K-means cluster plot. Ukukhanya komfanekiso we-X-PEEM, njengombala okwiFig. 2 kuhambelana nobunzulu bokufunxwa kwe-X-ray.
I-Cr efanayo kodwa imeko yekhemikhali eyahlukileyo ye-Fe ikhokelela kumonakalo owahlukileyo wefilimu ye-oxide kunye neepatheni zokugqwala kwi-Ce-2507 esebenza ngobushushu kunye ne-cold-rolled. Le propati ye-cold rolled Ce-2507 ifundwe kakuhle. Ngokuphathelele ukwakheka kwee-oxide kunye nee-hydroxide ze-Fe emoyeni ongqongileyo kulo msebenzi phantse ungathathi cala, iimpendulo zezi zilandelayo:
Ezi mpendulo zingasentla zenzeka kwezi meko zilandelayo ngokusekelwe kuhlalutyo lwe-X-PEEM. Igxalaba elincinci elihambelana ne-Fe0 linxulunyaniswa nesinyithi sesinyithi esingaphantsi. Impendulo ye-Fe yesinyithi kunye nokusingqongileyo iphumela ekwakhiweni komaleko we-Fe(OH)2 (i-equation (5)), ephucula isignali ye-Fe2+ kwi-Fe L-edge XAS. Ukuvezwa emoyeni ixesha elide kunokubangela ukwakheka kwe-Fe3O4 kunye/okanye ii-Fe2O3 oxides emva kwe-Fe(OH)252,53. Iifom ezimbini ezizinzileyo ze-Fe, i-Fe3O4 kunye ne-Fe2O3, nazo zinokwenziwa komaleko okhuselayo we-Cr3+ otyebileyo, apho i-Fe3O4 ikhetha isakhiwo esifanayo nesinamathelayo. Ubukho bazo zombini buphumela kwiimeko ezixutyiweyo ze-oxidation (i-XAS-1 spectrum). I-XAS-2 spectrum ihambelana kakhulu ne-Fe3O4. Ngelixa ukubonwa kwe-XAS-3 spectra kwiindawo ezininzi kubonise ukuguqulwa okupheleleyo kwi-γ-Fe2O3. Ekubeni ubunzulu bokungena kwe-X-rays evulekileyo bumalunga ne-50 nm, isignali evela kumaleko asezantsi ibangela ubunzulu obuphezulu be-A peak.
I-XPA spectrum ibonisa ukuba i-Fe component kwifilimu ye-oxide inesakhiwo esineengqimba kunye ne-Cr oxide layer. Ngokungafaniyo neempawu zokungashukumi ngenxa yokungalingani kwendawo ye-Cr2O3 ngexesha lokugqwala, nangona i-Cr2O3 ifana nengqimba kulo msebenzi, ukumelana nokugqwala okuphantsi kuyabonwa kule meko, ngakumbi kwiisampuli eziqengqelekayo ezibandayo. Ukuziphatha okubonwayo kunokuqondwa njengokungafani kwemeko ye-chemical oxidation kwingqimba ephezulu (Fe), echaphazela ukusebenza kokugqwala. Ngenxa ye-stoichiometry efanayo yomaleko ophezulu (i-iron oxide) kunye nomaleko osezantsi (i-chromium oxide)52,53 ukusebenzisana okungcono (ukunamathela) phakathi kwazo kukhokelela ekuthuthweni okucothayo kwee-ion zesinyithi okanye ze-oxygen kwi-lattice, nto leyo, ekhokelela ekwandeni kokugqwala. Ke ngoko, umlinganiselo we-stoichiometric oqhubekayo, oko kukuthi imeko enye ye-oxidation ye-Fe, ikhethwa kunotshintsho olukhawulezileyo lwe-stoichiometric. I-SDSS eguquliweyo kubushushu inomphezulu ofanayo, umaleko okhuselayo oxineneyo, kunye nokuxhathisa okungcono kokugqwala. Ngelixa kwi-SDSS eqengqelekayo ebandayo, ukubakho kweziqithi ezityebileyo ze-Fe3+ phantsi komaleko okhuselayo kuyaphula ukuthembeka komphezulu kwaye kubangele ukugqwala kwe-galvanic kunye ne-substrate ekufutshane, okukhokelela ekwehleni okukhulu kwe-Rp (Itheyibhile 1). I-spectrum ye-EIS kunye nokumelana kwayo nokugqwala kunciphile. Kuyabonakala ukuba ukusasazwa kwendawo kweziqithi ezityebileyo ze-Fe3+ ngenxa yokugqwala kweplastiki kuchaphazela kakhulu ukuxhathisa ukugqwala, okuyimpumelelo kulo msebenzi. Ke ngoko, olu phononongo lubonisa imifanekiso ye-spectroscopic microscopic yokunciphisa ukuxhathisa ukugqwala kweesampulu ze-SDSS ezifundwe yindlela yokugqwala kweplastiki.
Ukongeza, nangona ukuxubana nezinto ezinqabileyo zomhlaba kwiintsimbi zesigaba ezibini kubonisa ukusebenza okungcono, ukusebenzisana kwale nto yokongeza kunye ne-matrix yentsimbi nganye ngokwendlela yokuziphatha kokugqwala ngokwedatha ye-spectroscopic microscopy akukacaci. Ukubonakala kwezibonakaliso zeCe (nge-XAS M-edges) kubonakala kuphela kwiindawo ezimbalwa ngexesha lokuqengqeleka okubandayo, kodwa kuyanyamalala ngexesha lokuguqulwa okushushu kwe-SDSS, okubonisa ukuna kweCe kwindawo ye-matrix yentsimbi, endaweni yokuxubana okufanayo. Nangona kungaphuculi kakhulu iipropati zoomatshini ze-SDSS6,7, ukubakho kwezinto ezinqabileyo zomhlaba kunciphisa ubungakanani bezinto ezifakiweyo kwaye kucingelwa ukuba kuthintela ukugoba kwindawo yokuqala54.
Ukuqukumbela, lo msebenzi utyhila isiphumo sokungafani komphezulu kwi-corrosion ye-2507 SDSS eguqulwe nge-cerium ngokulinganisa umxholo weekhemikhali zezinto ze-nanoscale. Siphendula umbuzo wokuba kutheni intsimbi engagqwaliyo idlaka naphantsi komaleko we-oxide okhuselayo ngokulinganisa isakhiwo sayo se-microstructure, i-surface chemistry, kunye nokucubungula imiqondiso kusetyenziswa i-K-means clustering. Kuye kwafunyaniswa ukuba iziqithi ezityebileyo kwi-Fe3+, kubandakanya ukulungelelaniswa kwazo kwe-octahedral kunye ne-tetrahedral kulo lonke uphawu lwe-mixed Fe2+/Fe3+, zingumthombo womonakalo kunye nokugqwala kwefilimu ye-oxide eqengqelekayo ebandayo ye-SDSS. Iziqithi ze-Nanoislands ezilawulwa yi-Fe3+ zikhokelela ekuchaseni okungalunganga kokugqwala naxa kukho umaleko owaneleyo we-stoichiometric Cr2O3 passivating. Ukongeza kwinkqubela phambili yendlela ekumiseleni isiphumo sokungafani kweekhemikhali ze-nanoscale kwi-corrosion, umsebenzi oqhubekayo kulindeleke ukuba ukhuthaze iinkqubo zobunjineli ukuphucula ukumelana nokugqwala kweentsimbi ezingagqwali ngexesha lokwenza intsimbi.
Ukulungiselela ingot ye-Ce-2507 SDSS esetyenzisiweyo kolu phononongo, umxube oxutyiweyo oquka i-Fe-Ce master alloy evalwe ngetyhubhu yesinyithi ecocekileyo wanyibilikiswa kwisithando somlilo esiphakathi esingama-150 kg ukuvelisa intsimbi enyibilikisiweyo waza wagalelwa kwisikhunta. Umxube weekhemikhali olinganisiweyo (wt%) udweliswe kwiTheyibhile eyoNgezelelweyo 2. Iingot ziqala zenziwe zishushu zibe ziibhloko. Emva koko zafakwa kwi-1050°C kangangemizuzu engama-60 ukuze kufunyanwe intsimbi kwimeko yesisombululo esiqinileyo, zaze zacinywa emanzini ukuya kubushushu begumbi. Iisampulu ezifundiweyo zafundwa ngokweenkcukacha kusetyenziswa i-TEM kunye ne-DOE ukufunda izigaba, ubungakanani bengqolowa kunye nemofoloji. Ulwazi oluthe kratya malunga neesampulu kunye nenkqubo yemveliso lunokufumaneka kweminye imithombo6,7.
Iisampulu ze-cylindrical (φ10 mm×15 mm) zoxinzelelo olushushu zacutshungulwa ukuze i-axis yesilinda ihambelane necala lokuguquguquka kwebhloko. Uxinzelelo oluphezulu lobushushu lwenziwa kumaqondo obushushu ahlukeneyo kuluhlu lwe-1000-1150°C kusetyenziswa i-Gleeble-3800 thermal simulator kwisantya soxinzelelo oluqhubekayo kuluhlu lwe-0.01-10 s-1. Ngaphambi kokuguquguquka, iisampulu zafudunyezwa ngesantya se-10 °C s-1 imizuzu emi-2 kubushushu obukhethiweyo ukuze kususwe i-gradient yobushushu. Emva kokufikelela kufana kobushushu, isampuli yaguqulwa yaba lixabiso loxinzelelo lokwenyani le-0.7. Emva kokuguquguquka, iisampulu zacinywa ngokukhawuleza ngamanzi ukuze kugcinwe isakhiwo esikhubazekileyo. Isampuli eqinileyo emva koko isikwa ngokuhambelana necala loxinzelelo. Kolu phononongo luthile, sikhethe isampuli enemeko yoxinzelelo olushushu lwe-1050°C, 10 s-1 kuba ubunzima obubonwayo babuphezulu kunezinye iisampulu7.
Iisampulu ezinkulu (80 × 10 × 17 mm3) zesisombululo esiqinileyo seCe-2507 zisetyenziswe kwi-LG-300 enezigaba ezintathu ezingafaniyo ne-two-roll mill eneempawu ezilungileyo zoomatshini phakathi kwazo zonke ezinye izigaba zokuguquguquka6. Izinga loxinzelelo kunye nokunciphisa ubukhulu kwindlela nganye yi-0.2 m·s-1 kunye ne-5%, ngokulandelanayo.
I-Autolab PGSTAT128N electrochemical workstation yasetyenziswa kwimilinganiselo ye-SDSS electrochemical emva kokuqengqeleka okubandayo ukuya kutsho ekunciphiseni ubukhulu nge-90% (uxinzelelo olulinganayo lwe-1.0) kwaye emva kokucinezela ngobushushu kwi-1050°C nge-10 s-1 ukuya kuxinzelelo oluyinyani lwe-0.7. I-workstation ineseli ye-electrode ezintathu ene-electrode ye-calomel egcweleyo njenge-electrode yokubhekisa, i-graphite counter electrode, kunye nesampuli ye-SDSS njenge-electrode esebenzayo. Iisampuli zanqunyulwa zaba zii-cylinders ezinobubanzi be-11.3 mm, emacaleni apho iingcingo zobhedu zazithengiswa khona. Iisampuli zalungiswa nge-epoxy, zishiya indawo evulekileyo yokusebenza ye-1 cm2 njenge-electrode yokusebenza (icala elingaphantsi lesampuli ye-cylindrical). Lumka ngexesha lokulungiswa kwe-epoxy kunye nokusila kunye nokupolisha okulandelayo ukuze uphephe ukuqhekeka. Iindawo zokusebenza zagaywa zaza zapholishwa nge-diamond polishing suspension enobukhulu be-particle ye-1 μm, zahlanjwa ngamanzi acocekileyo kunye ne-ethanol, zaza zomiswa emoyeni obandayo. Ngaphambi kokulinganisa i-electrochemical, iisampuli ezipholisiweyo zazivezwa emoyeni kangangeentsuku ezininzi ukuze zenze ifilimu yendalo ye-oxide. Isisombululo samanzi se-FeCl3 (6.0 wt%), esizinzileyo ukuya kwi-pH = 1.0 ± 0.01 kunye ne-HCl ngokweengcebiso ze-ASTM, sisetyenziselwa ukukhawulezisa ukugqwala kwentsimbi engagqwali55 kuba iyagqwala xa kukho ii-ion ze-chloride ezinomthamo onamandla wokuxilisa kunye ne-pH ephantsi Imigangatho yeNdalo i-G48 kunye ne-A923. Faka isampuli kwisisombululo sovavanyo iyure e-1 ukuze ufikelele kwimeko ezinzileyo ngaphambi kokwenza naluphi na umlinganiselo. Kwiisampuli zesisombululo esiqinileyo, esenziwe ngobushushu, kunye ne-cold-rolled, umlinganiselo we-impedance wenziwe kwi-open circuit potentials (OPC) ye-0.39, 0.33, kunye ne-0.25 V, ngokulandelanayo, kuluhlu lwefrikhwensi ukusuka kwi-1 105 ukuya kwi-0.1 Hz kunye ne-amplitude ye-5 mV. Zonke iimvavanyo zeekhemikhali ziphindwe ubuncinane amaxesha ama-3 phantsi kweemeko ezifanayo ukuqinisekisa ukuphinda kwedatha.
Kwimilinganiselo ye-HE-SXRD, iibhloko zentsimbi eziziingxande eziphindwe kabini ezilinganisa i-1 × 1 × 1.5 mm3 zilinganisiwe ukuze kulinganiswe ukwakheka kwesigaba se-beam se-Brockhouse high-energy wiggler e-CLS, e-Canada56. Ukuqokelelwa kwedatha kwenziwe kwi-Debye-Scherrer geometry okanye i-transmission geometry kubushushu begumbi. Ubude be-X-ray obulinganiswe nge-LaB6 calibrator yi-0.212561 Å, ehambelana ne-58 keV, ephezulu kakhulu kuneye-Cu Kα (8 keV) esetyenziswa kakhulu njengomthombo we-X-ray webhubhoratri. Isampuli ibekwe kumgama we-740 mm ukusuka kwi-detector. Umthamo wokufumanisa wesampuli nganye yi-0.2 × 0.3 × 1.5 mm3, emiselwa bubungakanani be-beam kunye nobukhulu besampuli. Yonke idatha iqokelelwe kusetyenziswa isixhobo sokubona indawo iPerkin Elmer, isixhobo sokubona i-X-ray esinephaneli ethe tyaba, iiphikseli ezingama-200 µm, i-40×40 cm2 kusetyenziswa ixesha lokuvezwa lemizuzwana engama-0.3 kunye neefreyimu ezili-120.
Ukulinganiswa kwe-X-PEEM kweenkqubo ezimbini zeemodeli ezikhethiweyo kwenziwe kwisikhululo sokugqibela seBeamline MAXPEEM PEEM kwilebhu ye-MAX IV (eLund, eSweden). Iisampuli zalungiswa ngendlela efanayo nokulinganiswa kwe-electrochemical. Iisampuli ezilungisiweyo zagcinwa emoyeni iintsuku ezininzi zaza zakhutshwa igesi kwigumbi le-vacuum elinomoya ophezulu kakhulu ngaphambi kokuba zifakwe i-synchrotron photons. Isisombululo samandla somgca we-beam safunyanwa ngokulinganisa i-ion yield spectrum kummandla wokukhupha umoya ukusuka kwi-N 1 s ukuya kwi-1\(\pi _g^ \ast\) kufutshane ne-hv = 401 eV kwi-N2 kunye nokuxhomekeka kwamandla e-photon kwi-E3/2, 57. I-approximation spectra inike i-ΔE (ububanzi bomgca we-spectral) malunga ne-0.3 eV kuluhlu lwamandla olulinganisiweyo. Ngoko ke, isisombululo samandla e-beamline siqikelelwe ukuba yi-E/∆E = 700 eV/0.3 eV > 2000 kwaye i-flux ≈1012 ph/s ngokusebenzisa i-modified SX-700 monochromator ene-Si 1200-line mm−1 grating kwi-Fe 2p L2,3 edge, i-Cr 2p L2,3 edge, i-Ni 2p L2,3 edge, kunye ne-Ce M4,5 edge. Ngoko ke, isisombululo samandla e-beamline siqikelelwe ukuba yi-E/∆E = 700 eV/0.3 eV > 2000 kwaye i-flux ≈1012 ph/s ngokusebenzisa i-modified SX-700 monochromator ene-Si 1200-line mm−1 grating kwi-Fe 2p L2.3 edge, i-Cr 2p L2.3 edge, i-Ni 2p L2.3 edge, kunye ne-Ce M4.5 edge. Таким образом, энергетическое разрешение канала пучка было оценено как E/∆E = 700 эВ/0,3 эВ > 2000 и поток ≈1012 фсы модифицированного монохроматора SX-700 с решеткой Si 1200 штрихов/мм для Fe кромка 2p L2,3, кромка Cr 2p L2,3, кромка Ni 2p L2, 3, кромка Ni 2p L2, 3 Ngoko ke, isisombululo samandla setshaneli yemitha siqikelelwe njenge-E/∆E = 700 eV/0.3 eV > 2000 kwaye i-flux ≈1012 f/s kusetyenziswa i-modified SX-700 monochromator ene-Si grating ye-1200 lines/mm kwi-Fe edge 2p L2 ,3, Cr edge 2p L2.3, Ni edge 2p L2.3, kunye ne-Ce edge M4.5.因此，光束线能量分辨率估计為E/ΔE = 700 eV/0.3 eV > 2000 和通量≈1012 ph/s，通过使用带有1Si 120mm光栅的改进的SX-700 单色器用于Fe 2p L2,3 边缘、Cr 2p L2,3 边缘、Ni 2p L2,3 边缘和Ce M4,5 边缘.因此 , 光束线 能量 分辨率 为为为 δe = 700 EV/0.3 EV> 2000 kunye ≈1012 PH/S , 使用带有 带有 12 mm .改进 的 SX-700 单色器 于 于 用 用 用用Fe 2p L2.3 边缘、Cr 2p L2.3 边缘、Ni 2p L2.3 边缘和Ce M4.Ngoko ke, xa usebenzisa i-monochromator ye-SX-700 eguquliweyo ene-1200 line Si grating. 3, i-Cr edge 2p L2.3, i-Ni edge 2p L2.3 kunye ne-Ce edge M4.5.Ukuskena amandla e-photon ngamanyathelo e-0.2 eV. Kwi-energy nganye, imifanekiso ye-PEEM yarekhodwa kusetyenziswa i-TVIPS F-216 CMOS detector edityaniswe nefayibha ene-2 ​​x 2 bins, enika isisombululo se-1024 x 1024 pixels kwindawo yokujonga ye-20 µm. Ixesha lokuvezwa kwemifanekiso yayiyi-0.2 s, umyinge weefreyimu ezili-16. Amandla omfanekiso we-photoelectron akhethwa ngendlela yokubonelela ngesignali ye-electron yesibini ephezulu. Zonke izilinganiso zenziwe ngexesha eliqhelekileyo kusetyenziswa i-photon beam e-linearly polarized. Ulwazi oluthe kratya malunga nezilinganiso lunokufumaneka kwisifundo sangaphambili. Emva kokufunda imo yokufumanisa i-total electron yield (TEY) kunye nokusetyenziswa kwayo kwi-X-PEEM49, ubunzulu bovavanyo lwale ndlela buqikelelwa ukuba bumalunga ne-4-5 nm kwisignali ye-Cr kwaye malunga ne-6 nm kwi-Fe. Ubunzulu be-Cr busondele kakhulu kubukhulu befilimu ye-oxide (~4 nm)60,61 ngelixa ubunzulu be-Fe bukhulu kunobukhulu. I-XRD eqokelelwe kumphetho we-Fe L ngumxube we-XRD yee-iron oxides kunye ne-Fe0 evela kwi-matrix. Kwimeko yokuqala, amandla ee-electron ezikhutshiweyo avela kuzo zonke iintlobo zee-electron ezinokubakho ezifaka isandla kwi-TEY. Nangona kunjalo, isignali yesinyithi esicocekileyo ifuna amandla aphezulu e-kinetic ukuze ii-electron zidlule kumaleko we-oxide ziye kumphezulu kwaye ziqokelelwe yi-analyzer. Kwimeko enjalo, isignali ye-Fe0 ibangelwa kakhulu zii-electron ze-LVV Auger, kunye nee-electron zesibini ezikhutshiweyo zizo. Ukongeza, amandla e-TEY anegalelo kwezi electron abola ngexesha lendlela yokuphuma kwe-electron, nto leyo enciphisa ngakumbi impendulo ye-Fe0 spectral kwimephu yesinyithi ye-XAS.
Ukudibanisa idatha kwi-data cube (idatha ye-X-PEEM) linyathelo elibalulekileyo ekufumaneni ulwazi olufanelekileyo (iikhemikhali okanye iipropati zomzimba) ngendlela enemilinganiselo emininzi. Ukudibanisa i-K-means kusetyenziswa kakhulu kwiindawo ezahlukeneyo, kubandakanya umbono womatshini, ukucutshungulwa komfanekiso, ukuqatshelwa kwepateni engalawulwayo, ubukrelekrele bokwenziwa, kunye nohlalutyo lokwahlulahlula. Umzekelo, ukuhlanganisa i-K-means kusebenze kakuhle ekuhlanganiseni idatha yomfanekiso we-hyperspectral. Ngokomgaqo, kwidatha yeempawu ezininzi, i-K-means algorithm inokuyidibanisa ngokulula ngokusekelwe kulwazi malunga neempawu zayo (iipropati zamandla e-photon). Ukuhlanganisa i-K-means yi-algorithm ephindaphindayo yokwahlula idatha kumaqela e-K angagqubaniyo (ii-clusters), apho i-pixel nganye ikwiqela elithile ngokuxhomekeke kukusasazwa kwendawo yokungalingani kweekhemikhali kwisakhiwo se-microstructural sentsimbi. I-K-means algorithm ibandakanya izigaba ezibini: kwinqanaba lokuqala, ii-K centroids ziyabalwa, kwaye kwinqanaba lesibini, inqaku ngalinye linikwa iqela elinee-centroids ezikufutshane. Iziko lobunzima bomxhuzulane weqela lichazwa njenge-arithmetic mean yedatha points (XAS spectrum) yelo qela. Kukho imigama eyahlukeneyo yokuchaza ii-centroids ezikufutshane njengomgama we-Euclidean. Kumfanekiso wokufaka we-px,y (apho u-x no-y zisisombululo kwii-pixels), i-CK liziko lobunzima bomxhuzulane weqela; lo mfanekiso ungahlulwahlulwa (uhlanganiswe) ube zii-kluster ze-K kusetyenziswa i-K-means63. Amanyathelo okugqibela e-K-means clustering algorithm ngala:
Inyathelo lesi-2. Bala ubulungu bazo zonke ii-pixels ngokwe-centroid yangoku. Umzekelo, ibalwa ukusuka kumgama we-Euclidean d phakathi kweziko kunye ne-pixel nganye:
Inyathelo lesi-3 Yabela iphikseli nganye kwi-centroid ekufutshane. Emva koko bala kwakhona izikhundla ze-K centroid ngolu hlobo lulandelayo:
Inyathelo lesi-4. Phinda le nkqubo (ii-equations (7) kunye (8)) ide i-centroids idibane. Iziphumo zokugqibela zomgangatho wokudibanisa zihambelana kakhulu nokhetho olufanelekileyo lwee-centroids zokuqala. Kwisakhiwo sedatha ye-PEEM yemifanekiso yentsimbi, ngokuqhelekileyo i-X (x × y × λ) yityhubhu yedatha ye-array ye-3D, ngelixa ii-axes ze-x kunye ne-y zimele ulwazi lwesithuba (isisombululo se-pixel) kwaye i-axis ye-λ ihambelana nomfanekiso we-photon. energy spectral. I-algorithm ye-K-means isetyenziselwa ukuphonononga iindawo ezinomdla kwidatha ye-X-PEEM ngokwahlula ii-pixels (ii-clusters okanye ii-sub-blocks) ngokweempawu zazo ze-spectral kunye nokukhupha ii-centroids ezilungileyo (iiprofayili ze-XAS spectral) kwi-analyte nganye. cluster). Isetyenziselwa ukufunda usasazo lwesithuba, utshintsho lwe-spectral yendawo, ukuziphatha kwe-oxidation, kunye neemeko zeekhemikhali. Umzekelo, i-algorithm ye-K-means clustering yasetyenziselwa iindawo ze-Fe L-edge kunye ne-Cr L-edge kwiindawo ze-X-PEEM ezishushu nezibandayo. Amanani ahlukeneyo ee-K clusters (imimandla ye-microstructure) avavanyiwe ukuze kufunyanwe ii-clusters kunye nee-centroids ezifanelekileyo. Xa la manani eboniswa, ii-pixels zibuyiselwa kwii-cluster centroids ezifanelekileyo. Ukusasazwa kombala ngamnye kuhambelana nombindi we-cluster, okubonisa ulungelelwaniso lwendawo yezinto zeekhemikhali okanye zezinto ezibonakalayo. Ii-centroids ezikhutshiweyo ziindibaniselwano ezithe ngqo ze-spectra ecocekileyo.
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