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I-stainless steel stainless esetyenziswa ngokubanzi kunye neenguqulelo zayo ezisetyenzisiweyo zixhathisa ukubola kwiimeko eziphantsi ngenxa yomgangatho wokugqithisa owenziwe nge-chromium oxide. I-Corrosion kunye nokuguguleka kwensimbi ngokuqhelekileyo kuhambelana nokutshatyalaliswa kwezi zingqimba, kodwa kunqabile ngokubonakala kwe-inhomogeneities yomhlaba, kuxhomekeke kwinqanaba le-microscopic. Kulo msebenzi, i-nanoscale chemical surface heterogeneity, efunyenwe yi-spectroscopic microscopy kunye nohlalutyo lwe-chemometric, ilawula ngokungalindelekanga ukuphuka kunye nokubola kwe-cerium epholileyo epholileyo eguqulelwe i-super duplex stainless steel 2507 (SDSS) ngexesha lokuguqulwa kwayo okushushu. Nangona i-X-ray photoelectron microscopy ibonise ukugutyungelwa ngokulinganayo komgangatho we-Cr2O3 wendalo, ukusebenza kwe-passivation ye-SDSS epholileyo epholileyo yayimbi ngenxa yokusasazwa kwendawo ye-Fe3 + i-nanoislands ecebileyo kwi-Fe / Cr oxide layer. Olu lwazi lwesikali se-athomu lubonelela ngokuqonda okunzulu kwentsimbi ye-corrosion kwaye kulindeleke ukuba incede ukulwa nokubola kwesinyithi esifanayo se-alloy.
Ukusukela ekuvelisweni kwensimbi engenasici, i-anti-corrosion properties ze-ferrochrome ziye zabangelwa yi-chromium, eyenza i-oxides eyomeleleyo / i-oxyhydroxides kwaye ibonisa ukuziphatha okungahambiyo kwiindawo ezininzi. Xa kuthelekiswa nesiqhelo (i-austenitic kunye ne-ferritic) i-stainless steels 1, i-2, i-3, i-super duplex stainless steels (SDSS) inokumelana ne-corrosion engcono kunye neempawu ezibalaseleyo zoomatshini. Ukonyuka kwamandla omatshini kuvumela ukuba kube lula kunye noyilo oludibeneyo. Ngokwahlukileyo, i-SDSS yezoqoqosho inokumelana okuphezulu nokugrumba kunye ne-crevice corrosion, ekhokelela kubomi benkonzo obude, ngaloo ndlela yandisa isicelo sayo kulawulo longcoliseko, izikhongozeli zeekhemikhali, kunye ne-offshore oil and gas industry4. Nangona kunjalo, uluhlu olumxinwa lobushushu bonyango lobushushu kunye nokwakheka okungahambi kakuhle kuthintela ukusetyenziswa kwabo okubanzi. Ke ngoko, i-SDSS ilungisiwe ukuphucula ukusebenza okungentla. Ngokomzekelo, ukuguqulwa kweCe kwaqaliswa kwi-SDSS 2507 (Ce-2507) enomxholo ophezulu we-nitrogen6,7,8. I-elementi yomhlaba enqabileyo (Ce) ekugxininiseni okufanelekileyo kwe-0.08 wt.% inempembelelo enenzuzo kwiipropati zomatshini we-DSS, kuba iphucula ukucocwa kweenkozo kunye nokomelela komda weenkozo. Ukunxiba kunye nokuxhathisa umhlwa, amandla okuqina kunye nokomelela kwesivuno, kunye nokusebenza okushushu nako kuphuculwe9. Izixa ezikhulu zenitrogen zinokuthatha indawo yenickel ebizayo, nto leyo eyenza i-SDSS ingabizi kakhulu10.
Kutshanje, i-SDSS iye yakhubazeka ngokweplastiki kumaqondo obushushu ahlukeneyo (cryogenic, ebandayo kwaye eshushu) ukuphumeza iipropathi ezigqwesileyo zoomatshini6,7,8. Nangona kunjalo, ukuxhathisa okugqwesileyo kokugqwala kwe-SDSS ngenxa yobukho befilimu encinci ye-oxide kumphezulu ichatshazelwa zizinto ezininzi ezifana ne-heterogeneity yendalo ngenxa yobukho bezigaba ezingafaniyo ezinemida yeenkozo ezahlukeneyo, imvula engafunekiyo kunye nempendulo eyahlukileyo. ukuguqulwa kwezigaba ze-austenitic kunye ne-ferritic7. Ke ngoko, uphononongo lweepropathi zesizinda semicroscopic zezo filimu ukuya kuthi ga kwinqanaba lolwakhiwo lwe-elektroniki lubaluleka ekuqondeni ukubola kwe-SDSS kwaye kufuna iindlela ezinzima zokulinga. Ukuza kuthi ga ngoku, iindlela ezinobuzaza obuphezulu ezifana ne-Auger electron spectroscopy11 kunye ne-X-ray photoelectron spectroscopy12,13,14,15 kunye ne-X-ray enzima ye-photoemission microscopy (HAX-PEEM) 16 ngokubanzi aziphumelelanga ekuboneni ukungafani kweekhemikhali kwimigangatho yomhlaba. imichiza yeekhemikhali zento efanayo kwiindawo ezahlukeneyo zesithuba se-nanoscale. Izifundo ezininzi zakutsha nje ziye zanxibelelanisa i-oxidation yendawo yechromium kunye nokuziphatha okubonwayo kwe-austenitic stainless steels17, martensitic steels18 kunye ne-SDSS19,20. Nangona kunjalo, ezi zifundo zijolise ikakhulu kwimpembelelo ye-Cr heterogeneity (umzekelo, i-Cr3 + oxidation state) ekuxhathiseni ukubola. I-Lateral heterogeneity kwi-oxidation state yezinto inokubangelwa yiikhompawundi ezahlukeneyo ezineezakhi ezifanayo, ezifana ne-iron oxides. Ezi zixhobo, eziye zazuza ubungakanani obuncinci ngenxa yonyango lwe-thermomechanical, zisondelelene, kodwa zihluke ngokubunjwa kunye ne-oxidation state16,21. Ngoko ke, ukuze kubonwe ukuqhekeka kweefilimu ze-oxide kunye ne-pitting elandelayo, kuyimfuneko ukuqonda i-heterogeneity yomhlaba kwinqanaba le-microscopic. Ngaphandle kwezi mfuno, uqikelelo lobungakanani obufana ne-lateral heterogeneity kwi-oxidation, ngakumbi kwi-Fe kwi-nano- kunye ne-athomu yesikali, zisanqongophala, kwaye ukulungelelaniswa kwayo kunye nokumelana nokubola kuhlala kungahlolisiswanga. Kuze kube kutshanje, imeko yeekhemikhali zezinto ezahlukeneyo, ezifana ne-Fe kunye ne-Ca22, kwiisampuli zensimbi zibonakaliswe ngokobuninzi kusetyenziswa i-X-ray photoelectron microscopy (X-PEEM) kwizibonelelo ze-nanoscale synchrotron radiation. Idityaniswe ne-X-ray yekhemikhali yokufunxa i-spectroscopy (XAS), i-X-PEEM yenza imilinganiselo ye-XAS ibe nesisombululo esiphezulu sesithuba kunye ne-spectral, inika ulwazi lwekhemikhali malunga nokubunjwa kwezinto kunye nobume bemichiza kunye nesisombululo sesithuba ukuya kutsho kwisikali seenanometer ezingamashumi amabini anesithathu. . Olu qwalaselo lwe-spectromicroscopic lwesiqalo luququzelela ukuqwalaselwa kweekhemikhali zendawo kwaye lunokubonisa utshintsho lweekhemikhali kwindawo yomgangatho wentsimbi engazange iphandwe ngaphambili.
Olu pho nonongo lwandisa iingenelo ze-PEEM ekufumaneni ukungafani kweekhemikhali kwi-nanoscale kwaye ibonise indlela yokuhlalutya umgangatho we-athomu ye-athomu yokuqonda indlela yokuziphatha kwe-corrosion ye-Ce-2507. Isebenzisa indlela edibeneyo ye-K-means24 yekhemimethrikhi ukwenza imephu yekhemikhali yelizwe jikelele (hetero)homogeneity yezinto ezibandakanyekayo, ezimo zekhemikhali zibonakaliswe kumboniso wobalo. Ngokwahlukileyo kwi-corrosion eqaliswe ngokutshatyalaliswa kwefilimu ye-chromium oxide kwimeko yendabuko, ukunyanzeliswa okuncinci kunye nokuchasana kwe-corrosion okwangoku kubangelwa iindawo ze-Fe3 + ezicebileyo ze-nanoislands kufuphi ne-Fe / Cr oxide layer, enokuba yimpahla yokukhusela. Ioksidi iyonakalisa ifilimu enamachaphaza kwaye ibangele umhlwa.
Indlela yokuziphatha eyonakalisayo ye-SDSS 2507 ekhubazekileyo yavavanywa okokuqala kusetyenziswa imilinganiselo ye-electrochemical. Kwikhiwane. Umzobo 1 ubonisa iNyquist kunye neBode curves kwiisampuli ezikhethiweyo kwi-acidic (pH = 1) isisombululo se-aqueous FeCl3 kwiqondo lokushisa. I-electrolyte ekhethiweyo isebenza njenge-agent eyomeleleyo ye-oxidizing, ebonisa ukuthambekela kwefilimu ye-passivation ukudiliza. Nangona izinto eziphathekayo azizange zibe ne-pitting ezinzile kwiqondo lokushisa, uhlalutyo lunikeze ingqiqo malunga neziganeko ezinokuthi zingaphumeleli kunye nokubola okulandelayo. Isiphaluka esilinganayo (umzobo we-1d) sasisetyenziselwa ukulinganisa i-electrochemical impedance spectrum (EIS), kunye neziphumo ezifanelekileyo ezifanelekileyo ziboniswa kwiThebhile 1. Ii-semicircles ezingaphelelanga zibonakala kwiisampuli eziphathwe ngesisombululo kunye nokushisa, ngelixa iisemicircles ezixinzelelweyo zibonakala kwii-cold-rolled counterparts (Fig. Kwi-spectroscopy ye-EIS, i-radius ye-semicircle ingathathwa njengokumelana ne-polarization (Rp) 25,26. I-Rp yomgaqo weenqwelo-moya onesisombululo kwiTheyibhile yoku-1 imalunga ne-135 kΩ cm–2, nangona kunjalo, amaxabiso omgaqo weenqwelo-moya osetyenziweyo oshushu kunye nebandayo asezantsi kakhulu, 34.7 kunye ne-2.1 kΩ cm–2, ngokulandelelanayo. Oku kuncitshiswa okuphawulekayo kwe-Rp kubonisa umphumo onobungozi we-deformation yeplastiki kwi-passivation kunye nokumelana nokubola, njengoko kuboniswe kwiingxelo zangaphambili27,28,29,30.
i-Nyquist, b, c I-impedance ye-Bode kunye nemizobo yesigaba, kunye ne-d ehambelanayo imodeli yesekethe ehambelanayo, apho i-RS yi-resistance ye-electrolyte, i-Rp yi-resistance polarization, kunye ne-QCPE yi-oxide yecandelo eliqhelekileyo elisetyenziselwa ukulinganisa i-non-ideal capacitance (n). Imilinganiselo ye-EIS yenziwa kwindawo evulekileyo yesekethe.
I-constants ngexesha elinye iboniswe kwi-Bode plot, kunye ne-plateau kwi-high frequency range emele i-electrolyte resistance RS26. Njengoko i-frequency iyancipha, i-impedance iyanda kwaye i-angle yesigaba esibi ifunyenwe, ebonisa ukubusa kwe-capacitance. I-angle yesigaba iyanda, igcina ubuninzi ngaphezu koluhlu olubanzi olubanzi, kwaye emva koko iyancipha (Umfanekiso 1c). Nangona kunjalo, kuzo zontathu iimeko, obu buninzi bungaphantsi kwe-90 °, ebonisa ukuziphatha okungahambi kakuhle kwe-capacitive ngenxa ye-capacitive dispersion. Ngaloo ndlela, i-QCPE yesigaba esisisigxina (CPE) isetyenziselwa ukumela ukuhanjiswa kwe-interfacial capacitance evela kwi-roughness okanye i-inhomogeneity, ngokukodwa kwi-atomic scale, i-geometry ye-fractal, i-electrode porosity, i-non-uniform potential, kunye nejometri enemilo ye-electrodes31,32. Ukuphazamiseka kweCPE:
apho u-j linani lentelekelelo kwaye ω yi-angular frequency. I-QCPE yindawo ezimeleyo ehlala rhoqo ehambelana nendawo evulekileyo ye-electrolyte. I-n yinombolo yamandla engenamda echaza ukutenxa kwe-capacitor ukusuka kumandla afanelekileyo, okt i-n ekufutshane ku-1, i-CPE isondele kakhulu kwi-capacitive, ngelixa ukuba i-n isondele ku-zero, ibonakala ixhathisa. Ukuphambuka okuncinci kwe-n, kufutshane ne-1, kubonisa ukuziphatha okungahambi kakuhle kwe-capacitive yomphezulu emva kovavanyo lwe-polarization. I-QCPE ye-SDSS epholileyo epholileyo iphezulu kakhulu kunabalingane bayo, oku kuthetha ukuba umgangatho womphezulu awufani.
Ngokuhambelana neempawu ezininzi zokuxhathisa ukubola kweentsimbi ezingenasici, umxholo we-Cr ophezulu we-SDSS ngokubanzi ukhokelela ekuxhathiseni ukugqwala okugqwesileyo kwe-SDSS ngenxa yobukho befilimu ekhuselayo ekhuselayo kumphezulu17. Iifilimu ezinjalo ezidlulayo zihlala zizityebi kwi-Cr3 + oxides kunye / okanye i-hydroxides, ngokukodwa ngokudibanisa ne-Fe2+, i-Fe3+ oxides kunye / okanye (i-oxy) i-hydroxides33. Ngaphandle kokufana komphezulu ofanayo, i-passivating oxide layer, kwaye kungabikho ukuqhekeka komphezulu ngokwemilinganiselo emincinci6,7, i-corrosion behavior ye-SDSS esebenza eshushu kunye ne-cold-rolled-rolled yahlukile, ngoko ke uphando olunzulu lweempawu ze-microstructural luyimfuneko kwi-deformation yensimbi.
I-microstructure ye-deformed steel stainless steel yafundwa ngokobungakanani kusetyenziswa i-intrinsic kunye ne-synchrotron i-X-rays yamandla aphezulu (iMizobo eyoNgezelelweyo ye-1, i-2). Uhlalutyo oluneenkcukacha lunikiwe kuLwazi oloNgezelelweyo. Nangona kukho ukuvumelana ngokubanzi malunga nohlobo lwesigaba esikhulu, ukungafani kwiinqununu zesigaba sobuninzi zifunyenwe, ezidweliswe kwi-Supplementary Table 1. Ezi zintlukwano zinokuthi zibangelwa yi-inhomogeneous phase fractions on the surface kunye nomthamo, ochaphazelekayo ngokwahlukana kwe-X-ray diffraction (XRD) yokufumanisa ubunzulu. ) ngemithombo eyahlukeneyo yamandla yesiganeko photons34. Ngokuthelekisa amaqhezu aphezulu e-austenite kwisampulu eqengqelekisiweyo ebandayo egqitywe yi-XRD evela kumthombo waselabhorethri abonisa ukunyanzelwa okungcono kunye nokunganyangeki kwe-corrosion35, ngelixa iziphumo ezichaneke ngakumbi kunye nezibalo zibonisa iintsingiselo ezichaseneyo kumaqhezu esigaba. Ukongezelela, ukuxhatshazwa kwe-corrosion yensimbi kuxhomekeke kwinqanaba lokucocwa kweenkozo, ukunciphisa ubungakanani beenkozo, ukunyuka kwe-microdeformations kunye nokuxinana kwe-dislocation okwenzeka ngexesha lonyango lwe-thermomechanical36,37,38. Iimpawu ezishushu ezisetyenzisiweyo zibonise ubume obuziinkozo, obubonisa i-grain-size grains, ngelixa iindandatho ezigudileyo ezibonwa kwiimpawu ezipholileyo (i-Supplementary Fig. 3) zibonisa ukulungiswa okuziinkozo okubalulekileyo kwi-nanosize kumsebenzi wangaphambili. Oku kufuneka kuthande ifilimu yokwenziwa. ukubunjwa kunye nokwanda kokumelana nomhlwa. Uxinaniso oluphezulu lwe-dislocation luhlala lunxulunyaniswa nokuchasana okuphantsi kwi-pitting, evumelana kakuhle nemilinganiselo ye-electrochemical.
Utshintsho kwimeko yekhemikhali ye-microdomains yezinto eziphambili zafundwa ngokucwangcisiweyo kusetyenziswa i-X-PEEM. Nangona kukho izinto ezininzi zokuhlanganisa, i-Cr, i-Fe, i-Ni kunye ne-Ce39 zikhethwa apha, ekubeni i-Cr yinto ephambili yokwenza ifilimu ye-passive, i-Fe yeyona nto iphambili yentsimbi, kunye ne-Ni yokwandisa i-passivation kunye nokulinganisa isigaba se-ferrite-austenitic. Ulwakhiwo kunye nohlengahlengiso yinjongo kaCe. Ngokulungisa i-synchrotron beam energy, i-XAS ibambe iimpawu eziphambili ze-Cr (i-L2.3 edge), i-Fe (L2.3 edge), i-Ni (i-L2.3 edge), kunye ne-Ce (M4.5 edge) ukusuka phezulu. -2507 SDSS. Uhlalutyo lwedatha olufanelekileyo lwenziwa ngokubandakanya ukulinganisa amandla kunye nedatha epapashiweyo (umzekelo, i-XAS kwi-Fe L2, i-3 ribs40,41).
Kwikhiwane. Umzobo we-2 ubonisa imifanekiso ye-X-PEEM ye-hot-worked (Umfanekiso 2a) kunye ne-cold-rolled (Fig. 2d) Ce-2507 SDSS kunye ne-XAS Cr kunye ne-Fe L2,3 imiphetho ehambelanayo kwiindawo eziphawulwe ngabanye. I-L2,3 XAS edge iphonononga i-3d state engasebenziyo yee-electron emva kwe-photoexcitation kwi-2p3 / 2 (i-L3 edge) kunye ne-2p1 / 2 (i-L2 edge) ye-spin-orbit yamanqanaba okuqhekeza. Ulwazi malunga nemeko ye-valence ye-Cr yafunyanwa kuhlalutyo lwe-X-ray ye-diffraction ye-L2,3 edge kwi-Fig. 2b, d. Uthelekiso lwekhonkco. I-42, i-43 ibonise ukuba iincopho ezine ze-A (578.3 eV), B (579.5 eV), C (580.4 eV), kunye ne-D (582.2 eV) zabonwa kufuphi nomda we-L3, ezibonisa i-octahedral Cr3 + ion, ehambelana ne-Cr2O3. I-spectra yovavanyo iyavumelana nezibalo zethiyori, njengoko kuboniswe kwiipaneli ze-b kunye ne-e, ezifunyenwe kwi-multiple crystal field calculations kwi-interface ye-Cr L2.3 usebenzisa i-crystal field ye-2.0 eV44. Yomibini imiphezulu ye-SDSS esetyenzisiweyo eshushu kwaye iqengqeleke ngokubanda igqunywe ngomgangatho ofanayo we-Cr2O3.
umfanekiso we-Thermal we-X-PEEM ye-SDSS eshushu ehambelana nomphetho b Cr L2.3 kunye nomphetho c Fe L2.3, d Umfanekiso we-Thermal X-PEEM ye-SDSS epholileyo edibeneyo ehambelana nomphetho e-Cr L2.3 kunye ne-f Fe L2.3 yecala (e) . Umboniso we-XAS ocetywe kwiindawo ezahlukeneyo zesithuba eziphawulwe kwimifanekiso eshushu (a, d) ngemigca echokoziweyo e-orenji ku-(b) kunye (e) imele imbonakalo ye-XAS efanisiweyo ye-Cr3+ enexabiso le-crystal field ye-2.0 eV. Kwimifanekiso ye-X-PEEM, i-palette ye-thermal isetyenziselwa ukuphucula ukufundeka komfanekiso, apho imibala esuka eluhlaza okwesibhakabhaka ukuya ebomvu ihambelana nokunyanzeliswa kwe-X-ray (ukusuka ephantsi ukuya phezulu).
Kungakhathaliseki ukuba imo yekhemikhali yale miba yesinyithi, imo yekhemikhali yokongezwa kwe-Ni kunye ne-Ce i-alloying element kuzo zombini iisampuli zahlala zifana. Umzobo owongezelelweyo. Kwikhiwane. I-5-9 ibonisa imifanekiso ye-X-PEEM kunye ne-spectra ye-XAS ehambelanayo ye-Ni kunye ne-Ce kwiindawo ezahlukeneyo kumphezulu we-hot-worked and cold-rolled samples. I-Ni XAS ibonisa imo ye-oxidation ye-Ni2+ phezu komhlaba wonke olinganisiweyo wemizekelo eshushu-esetyenziweyo kunye nebandayo (Ingxoxo eyoNgezelelweyo). Kuyaphawuleka ukuba kwimeko yeesampulu ezisetyenzisiweyo ezishushu, umqondiso we-XAS we-Ce awubonwa, ngelixa i-spectrum ye-Ce3 + yeesampuli ezipholileyo zibonwa ngexesha elinye. Uqwalaselo lwamabala e-Ce kwiisampuli eziqengqelekayo ezibandayo lubonise ukuba i-Ce ikhona ikakhulu ngokohlobo lwemvula.
Kwi-SDSS ye-thermal deformed, akukho tshintsho lwesakhiwo sendawo kwi-XAS yabonwa kumda we-Fe L2.3 (umzobo 2c). Nangona kunjalo, njengoko kubonisiwe kwifig. I-2f, i-matrix ye-Fe itshintsha nge-microscopically imeko yeekhemikhali kwiindawo ezisixhenxe ezikhethiweyo ezikhethiweyo kwi-SDSS eqengqelekayo ebandayo. Ukongezelela, ukuze ufumane ingcamango echanekileyo yokutshintsha kwimeko ye-Fe kwiindawo ezikhethiweyo kwi-Fig. 2f, izifundo zendawo zendawo zenziwa (umzobo we-3 kunye ne-Supplementary Fig. 10) apho imimandla encinci yeesetyhula yakhethwa. I-spectra ye-XAS ye-Fe L2, i-3 edge ye-α-Fe2O3 iinkqubo kunye ne-Fe2 + octahedral oxides zenziwe imodeli ngokusebenzisa i-multiplet crystal field calculations usebenzisa i-crystal fields ye-1.0 (Fe2 +) kunye ne-1.0 (Fe3 +)44. Siyaqaphela ukuba i-α-Fe2O3 kunye ne-γ-Fe2O3 zinee-symmetries ezahlukeneyo zendawo45,46, i-Fe3O4 indibaniselwano zombini i-Fe2 + & Fe3 +, 47, kunye ne-FeO45 njenge-divalent ngokusemthethweni i-Fe2 + oxide (3d6). Siyaqaphela ukuba i-α-Fe2O3 kunye ne-γ-Fe2O3 zinee-symmetries ezahlukeneyo zendawo45,46, i-Fe3O4 inokudibanisa zombini i-Fe2 + & Fe3 +, 47, kunye ne-FeO45 njenge-divalent ngokusemthethweni i-Fe2 + oxide (3d6).Qaphela ukuba i-α-Fe2O3 kunye ne-γ-Fe2O3 zinee-symmetries ezahlukeneyo zendawo45,46, i-Fe3O4 idibanisa zombini i-Fe2 + kunye ne-Fe3 +, i-47 kunye ne-FeO45 ngendlela ye-divalent oxide Fe2 + (3d6).Qaphela ukuba i-α-Fe2O3 kunye ne-γ-Fe2O3 zinee-symmetries ezahlukeneyo zendawo45,46, i-Fe3O4 ineendibaniselwano ze-Fe2 + kunye ne-Fe3 +, i-47 kunye ne-FeO45 isebenza njenge-divalent esemthethweni ye-Fe2 + oxide (3d6). Zonke i-Fe3+ ion kwi-α-Fe2O3 zinezithuba ze-Oh kuphela, ngelixa i-γ-Fe2O3 idla ngokuchazwa njenge-Fe3+ t2g [Fe3+5/3V1/3] umz. i-O4 spinel enezithuba umz. Ngoko ke, i-Fe3+ ion kwi-γ-Fe2O3 zineendawo zombini ze-Td kunye ne-Oh. Njengoko kukhankanyiwe kumsebenzi wangaphambili, nangona i-intensites ratios of the two is different, intensity ratio yabo umz / t2g yi ≈1, ngelixa kulo mzekelo umlinganiselo wokuqina oqatshelweyo umz / t2g malunga ne-1. Oku kulawula ukuba kunokwenzeka kuphela i-Fe3 + ekhoyo kule meko. Ukuqwalasela imeko ye-Fe3O4 kunye nokudibanisa kwe-Fe2 + kunye ne-Fe3 +, kwaziwa ukuba i-ebuthakathaka (eyomelele) ibonakaliso yokuqala kwi-L3 edge ye-Fe ibonisa ukungabikho komncinci (omkhulu) kwi-t2g state. Oku kusebenza kwi-Fe2 + (Fe3 +), ebonisa ukwanda kophawu lokuqala olubonisa ukwanda komxholo we-Fe2 + 47. Ezi ziphumo zibonisa ukuba i-Fe2 + kunye ne-γ-Fe2O3, i-α-Fe2O3 kunye / okanye i-Fe3O4 ibaluleke kakhulu kwiindawo ezibandayo ezidibeneyo.
Ifotoemission electron eyandisiweyo imifanekiso eshushu ye (a, c) kunye (b, d) XAS spectra ngapha komphetho we-Fe L2,3 kwiindawo ezahlukeneyo zesithuba phakathi kwemimandla ekhethiweyo ye-2 kunye no-E kumakhiwane. 2d.
Idatha yovavanyo efunyenweyo (umzobo we-4a kunye ne-Supplementary Fig. 11) yacwangciswa kwaye ithelekiswa nezo zixutywayo ezicocekileyo 40, 41, 48. Ngokwenene, iintlobo ezintathu ezahlukeneyo zovavanyo olujongwe ngovavanyo lwe-Fe L-edge XAS spectra (XAS-1, XAS-2 kunye ne-XAS-3: Umzobo 4a) wabonwa kwiindawo ezahlukeneyo zendawo. Ngokukodwa, i-spectrum efana ne-2-a (echazwe njenge-XAS-1) kwi-Fig. 3b yabonwa kuwo wonke ummandla womdla, ilandelwa yi-2-b spectrum (ebhalwe XAS-2), ngelixa i-spectrum efana ne-E-3 yabonwa kwifig. I-3d (ekubhekiswa kuyo njenge-XAS-3) iye yabonwa kwiindawo ezithile zendawo. Ngokuqhelekileyo, iiparamitha ezine zisetyenziselwa ukuchonga iindawo ze-valence ezikhoyo kwisampula yeprobe: (1) i-L3 kunye ne-L2 iimpawu ze-spectral, (2) izikhundla zamandla ze-L3 kunye ne-L2 iimpawu, (3) i-L3-L2 umahluko wamandla, (4) i-L2 intensity ratio / L3. Ngokwemibono ebonakalayo (umzobo 4a), zonke iinqununu ezintathu ze-Fe, ezizezi, Fe0, Fe2 +, kunye ne-Fe3 +, zikhona kumphezulu we-SDSS efundwayo. Umlinganiselo obaliweyo we-intensity ratio L2/L3 uphinde wabonisa ubukho bawo omathathu amacandelo.
a Kuqatshelwe iinkcukacha ezintathu zovavanyo ezahlukeneyo (imigca eqinileyo XAS-1, XAS-2 kunye XAS-3 ihambelana ne-2-a, 2-b kunye ne-E-3 kwi-Fig. 2 kunye ne-Fig. 3) xa kuthelekiswa ne-XAS efanisiweyo yokuthelekisa i-spectra, i-octahedrons Fe2+, i-Fe3+, ixabiso le-crystal field ye-1. idatha yovavanyo (XAS-1, XAS-2, XAS-3) kunye nedatha ehambelanayo ye-LCF (umgca omnyama oqinileyo), kunye nokuthelekisa i-XAS-3 spectra kunye ne-Fe3O4 (imeko edibeneyo ye-Fe) kunye nemigangatho ye-Fe2O3 (i-Fe3 + ecocekileyo).
Inhlanganisela yomgca (LCF) ehambelana nemigangatho emithathu ye-40,41,48 yayisetyenziselwa ukulinganisa ukubunjwa kwe-iron oxide. I-LCF yaphunyezwa kwii-spectra ezintathu ezikhethiweyo ze-Fe L-edge XAS ezibonisa owona mahluko aphezulu, angala, i-XAS-1, i-XAS-2 kunye ne-XAS-3, njengoko kubonisiwe kumfanekiso we-4b-d. Ukufakwa kwe-LCF, i-10% ye-Fe0 yaqwalaselwa kuzo zonke iimeko ngenxa ye-ledge encinci esiyibonile kuyo yonke idatha kunye nenyaniso yokuba isinyithi se-ferrous iyona nto iphambili yentsimbi. Enyanisweni, ubunzulu bokulingwa kwe-X-PEEM ye-Fe (~ 6 nm) 49 bukhulu kunoqikelelo oluqikelelweyo lwe-oxidation layer (kancinci> 4 nm), evumela ukufunyanwa kwesignali kwi-matrix yensimbi (Fe0) phantsi komgca we-passivation. Enyanisweni, ubunzulu bokulingwa kwe-X-PEEM ye-Fe (~ 6 nm) 49 bukhulu kunoqikelelo oluqikelelweyo lwe-oxidation layer (kancinci> 4 nm), evumela ukufunyanwa kwesignali kwi-matrix yensimbi (Fe0) phantsi komgca we-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, i-probe ye-X-PEEM ubunzulu be-Fe (~ 6 nm) i-49 inkulu kunobunzima obucatshangelwayo be-oxidation layer (kancinci> i-4 nm), okwenza kube lula ukufumanisa isignali kwi-matrix yensimbi (Fe0) phantsi komgca we-passivation.Enyanisweni, i-X-PEEM ibona i-Fe (~ 6 nm) i-49 enzulu kunobunzima obulindelekileyo be-oxide layer (ngaphezulu nje kwe-4 nm), ivumela ukufunyanwa kwezibonakaliso kwi-matrix yensimbi (Fe0) ngaphantsi kwe-passivation layer. Iindibaniso ezahlukeneyo ze-Fe2+ kunye ne-Fe3+ zenziwa ukufumana esona sisombululo sisesona sisesona sinokwenzeka kwidatha yovavanyo olujongweyo. Kwikhiwane. Umzobo we-4b ubonisa ukudibanisa kwe-Fe2 + kunye ne-Fe3 + kwi-spectrum ye-XAS-1, apho imilinganiselo ye-Fe2 + kunye ne-Fe3 + isondele, malunga ne-45%, ebonisa imeko ye-oxidation edibeneyo ye-Fe. Ngexa kwi-spectrum ye-XAS-2, ipesenti ye-Fe2+ kunye ne-Fe3+ iba yi-~30% kunye ne-60%, ngokulandelelanayo. Umxholo we-Fe2 + ungaphantsi kune-Fe3 +. Umlinganiselo we-Fe2 + ukuya kwi-Fe3 we-1: 2 uthetha ukuba i-Fe3O4 inokubunjwa kumlinganiselo ofanayo we-Fe ion. Ukongezelela, kwi-spectrum ye-XAS-3, iipesenti ze-Fe2 + kunye ne-Fe3 + zitshintshile zibe ~ ~ 10% kunye ne-80%, ebonisa ukuguqulwa okuphezulu kwe-Fe2 + kwi-Fe3 +. Njengoko kukhankanyiwe ngasentla, i-Fe3 + inokuvela kwi-α-Fe2O3, γ-Fe2O3 okanye i-Fe3O4. Ukuqonda owona mthombo we-Fe3 +, i-XAS-3 spectra icwangciswe kunye nemigangatho eyahlukeneyo ye-Fe3 + kwi-Fig. 4e ebonisa ukufana nayo yonke imigangatho emibini xa i-Peak B iqwalaselwa. Nangona kunjalo, ubukhulu begxalaba (A: ukusuka kwi-Fe2 +) kunye nomlinganiselo we-B / A ubonisa ukuba i-spectrum ye-XAS-3 isondele kodwa ayifani ne-γ-Fe2O3. Xa kuthelekiswa nobuninzi be-γ-Fe2O3, i-Fe 2p XAS intensity ye-A SDSS peak iphezulu kancinane (Fig. 4e), ebonisa ukuqina kwe-Fe2 + ephezulu. Nangona i-spectrum ye-XAS-3 ifana ne-γ-Fe2O3, apho i-Fe3 + ikhona kuzo zombini izikhundla ze-Oh kunye ne-Td, ukuchongwa kweendawo ezahlukeneyo ze-valence kunye nokulungelelaniswa kuphela nge-L2,3 edge okanye i-L2 / L3 intensity ratio kuseyingxaki. isihloko esiqhubekayo sengxoxo ngenxa yobunzima bezinto ezahlukeneyo ezibandakanyekayo kwi-spectrum yokugqibela41.
Ukongeza kucalucalulo olubonakalayo lweekhemikhali zemimandla yemimandla ekhethiweyo enomdla echazwe ngasentla, i-heterogeneity yeekhemikhali zehlabathi yezinto eziphambili ze-Cr kunye ne-Fe zavavanywa ngokuhlela yonke imbonakalo ye-XAS efunyenwe kumphezulu wesampulu kusetyenziswa indlela ye-K-ithetha ukuhlanganisana. Iiprofayili zomda we-Cr L zamiselwa ngendlela yokwenza amaqela amabini afanelekileyo asasazwa ngokwendawo kwiindawo ezishushu ezisetyenzisiweyo kunye nezibandayo eziboniswe kwiMifanekiso. 5. Kucacile ukuba akukho lutshintsho lwesakhiwo sendawo luye lwabonwa, kuba iisentimitha ezimbini ze-XAS Cr spectra zifana kakhulu. Ezi iimilo ezibonakalayo zamaqela amabini ziphantse zafana nezo zihambelana ne-Cr2O342, okuthetha ukuba iileya ze-Cr2O3 zisasazwe ngokufanayo phezu kwe-SDSS.
Iqela le-K-lithetha imimandla ye-L-edge Cr, b ehambelana neecentroids ze-XAS. Iziphumo ze-K-zithetha i-X-PEEM ukuthelekiswa kwe-SDSS epholileyo: iqoqo le-K-ithetha imimandla ye-Cr L2,3 kunye ne-d ehambelana ne-XAS centroids.
Ukubonisa imephu yomphetho entsonkothileyo ye-FeL, amaqela amane kunye namahlanu alungelelanisiweyo kunye neecentroids ezinxulumene nawo (usasazo lwe-spectral) zisetyenziselwa imizekelo eshushu kunye nebandayo eqengqelekayo, ngokulandelanayo. Ngoko ke, ipesenti (%) ye-Fe2 + kunye ne-Fe3 + inokufumaneka ngokulungelelanisa i-LCF eboniswe kwi-Fig.4. I-pseudoelectrode enokubakho i-Epseudo njengomsebenzi we-Fe0 yayisetyenziselwa ukuveza i-microchemical inhomogeneity yefilimu ye-oxide yomhlaba. I-Epseudo iqikelelwa ngokungqongqo ngumgaqo wokuxuba,
apho \(\rm{E}_{\rm{Fe}/\rm{Fe}^{2 + (3 + )}}\) ilingana \(\rm{Fe} + 2e^ – \to\rm { Fe}^{2 + (3 + )}\), eyi-0.440 kunye ne-0.036 V, ngokulandelelanayo. Iindawo ezinokuthi zincinci zinomxholo ophezulu we-Fe3 + compounds. Ukuhanjiswa okunokubakho kwisampulu ekhubazekileyo ye-thermal kunobumba obunqamlekileyo kunye noshintsho oluphezulu malunga ne-0.119 V (Umfanekiso 6a, b). Oku kusasazwa okunokwenzeka kuhambelana ngokusondeleyo kwi-topography yomhlaba (Umfanekiso 6a). Azikho ezinye iinguqu ezinxulumene nezikhundla eziye zabonwa kwi-lamellar yangaphakathi engaphantsi (umzobo 6b). Ngokuchasene noko, ukudibanisa i-oxides ehlukeneyo kunye nemixholo eyahlukeneyo ye-Fe2 + kunye ne-Fe3 + kwi-SDSS epholileyo, indalo engabonakaliyo ye-pseudopotential inokubonwa (Umfanekiso 6c, d). I-Fe3 + oxides kunye / okanye (i-oxy) i-hydroxides yizona nxalenye eziphambili ze-corrosion kwintsimbi kwaye zingena kwi-oxygen kunye namanzi50. Kule meko, kunokubonwa ukuba iziqithi ezizityebi kwi-Fe3 + zihanjiswa kwindawo kwaye zinokuthi zithathwe njengeendawo zokubola. Kule meko, i-gradient kwintsimi enokwenzeka, kunokuba ixabiso elipheleleyo lezinto ezinokubakho, linokuthi lithathelwe ingqalelo njengesalathisi sendawo yemimandla ye-corrosion esebenzayo51. Ukusabalalisa okungafaniyo kwe-Fe2 + kunye ne-Fe3 + kumphezulu we-SDSS epholileyo epholileyo kunokutshintsha iipropati zeekhemikhali zendawo kwaye zinikeze indawo esebenzayo ngakumbi kwifilimu ye-oxide yokuqhekeka kunye nokuphendula kwe-corrosion, ngaloo ndlela ivumela i-matrix yensimbi ephantsi ukuba iqhube ngokuqhubekayo, okubangela ukuba inhomogeneity yangaphakathi. kunye nokunciphisa iimpawu zokukhusela ze-passivating layer.
I-K-mean clusters ye-Fe L2,3 edge regions kunye ne-XAS centroids ehambelanayo ye-a–c esebenza ngokushushu i-X-PEEM kunye ne-d–f eqengqelekayo e-SDSS. a, d K-ithetha iploti yeqela eligqunywe kumfanekiso we X-PEEM. Uqikelelo lwezinto ezinokwenzeka zepseudoelectrode (epseudo) zikhankanyiwe kunye ne-K-ithetha imizobo yeqela. Ukukhanya komfanekiso we-X-PEEM njengombala kwi-Fig.
Ngokulinganayo iyunifomu ye-Cr kodwa imo yeekhemikhali ezahlukeneyo ze-Fe ikhokelela kwimvelaphi eyahlukileyo yokuqhekeka kwefilimu ye-oxide kunye neepateni zokubola kwi-Ce-2507 eshushu kunye nebandayo. Le propathi ye-Ce-2507 epholileyo epholileyo iyaziwa. Ngokubhekiselele ekubunjweni kweeoksidi kunye neehydroxides ze-Fe emoyeni we-atmospheric, ezi mpendulo zilandelayo zivaliwe kulo msebenzi njengeempendulo ezingathathi hlangothi:
Ngokusekelwe kumlinganiselo we-X-PEEM, ukusabela okungentla kwenzeka kwezi meko zilandelayo. Igxalaba elincinci elihambelana ne-Fe0 lidibene nentsimbi ephantsi yensimbi. Ukusabela kwe-metallic Fe kunye nokusingqongileyo kukhokelela ekwenziweni kwe-Fe(OH)2 umaleko (inxaki (5)), ekhulisa umqondiso we-Fe2+ kwi-XAS yomgca we-L we-Fe. Ukutshatyalaliswa kwexesha elide emoyeni kuya kubangela ukubunjwa kwe-Fe3O4 kunye / okanye i-Fe2O3 oxides emva kwe-Fe (OH) 252,53. Iintlobo ezimbini ze-Fe, i-Fe3O4 kunye ne-Fe2O3, inokuphinda ifake kwi-Cr3 + ecebileyo yokukhusela, apho i-Fe3O4 ikhetha i-uniform kunye nesakhiwo esihlangeneyo. Ubukho beziphumo zombini kwimixube ye-oxidation states (XAS-1 spectrum). I-spectrum ye-XAS-2 ihambelana kakhulu ne-Fe3O4. Ngelixa umboniso we-XAS-3 ojongwe kwiindawo ezininzi ubonise uguqulo olupheleleyo kwi-γ-Fe2O3. Ekubeni ii-X-reyi ezingasongwanga zinobunzulu bokungena obumalunga ne-50 nm, umqondiso osuka kumaleko ongaphantsi uphumela kuxinzelelo oluphezulu lwencopho ye-A.
I-spectrum ye-XRD ibonisa ukuba i-Fe component kwifilimu ye-oxide inesakhiwo se-layer, esidibaniswe ne-Cr oxide layer. Ngokwahlukileyo kwi-passivation ye-corrosion ngenxa ye-inhomogeneity yendawo ye-Cr2O317, nangona umaleko ofanayo we-Cr2O3 kolu phononongo, ukuxhathisa okuphantsi kwe-corrosion kwabonwa kule meko, ngakumbi kwiisampuli eziqengqelekayo ezibandayo. Ukuziphatha okubonwayo kunokuqondwa njenge-heterogeneity yemeko ye-chemical oxidation yomgangatho ophezulu (Fe) ochaphazela ukusebenza kwe-corrosion. Ukuhanjiswa okucothayo kwesinyithi okanye i-oxygen ion kwi-lattice ngenxa ye-stoichiometry efanayo ephezulu (i-Fe oxide) kunye neengqimba ezisezantsi (i-Cr oxide) i-52,53 ikhokelela ekusebenzisaneni okungcono (ukubambelela) phakathi kwabo. Oku, kwakhona, kuphucula ukuxhathisa umhlwa. Ngoko ke, i-stoichiometry eqhubekayo, okt imo enye ye-oxidation ye-Fe, ikhethwa kwiinguqu ze-stoichiometric ngokukhawuleza. I-SDSS ekhubazeke ngokwe-Thermally inomphezulu ofanayo ngakumbi kunye nomgangatho okhuselweyo oxineneyo, obonelela ngokumelana nokukhula okungcono. Nangona kunjalo, kwi-SDSS epholileyo, ubukho beziqithi ze-Fe3 + ezizityebi phantsi komgangatho okhuselekileyo zonakalisa ingqibelelo yomhlaba kwaye zibangele i-galvanic corrosion ye-substrate esondeleyo, ekhokelela ekunciphiseni kwe-Rp (Itheyibhile 1) kwi-spectra ye-EIS kunye ne-corrosion yayo. ukuxhathisa. Ngoko ke, iziqithi ezisasazwa ekuhlaleni ezityebileyo kwi-Fe3 + ngenxa yokuguqulwa kweplastiki ikakhulu zinempembelelo ekusebenzeni kokumelana nokubola, okuyimpumelelo kulo msebenzi. Ke ngoko, olu phononongo lubonisa i-spectromicrographs yokunciphisa ukuxhathisa ukubola ngenxa yokuguqulwa kweplastiki yeesampulu ezifundiweyo ze-SDSS.
Ngaphaya koko, ngelixa umxube womhlaba onqabileyo kwizigaba ezimbini zentsimbi zisebenza ngcono, ukusebenzelana kwesi siqalelo esongeziweyo kunye ne-matrix yentsimbi yomntu ngamnye ngokwendlela yokuziphatha komhlwa kuhlala kunzima ngokusekwe kwi-spectroscopic microscopy. Umqondiso we-Ce (kunye ne-XAS M-edge) ubonakala kuphela kwizithuba ezimbalwa ngexesha lokuqengqeleka okubandayo, kodwa uyanyamalala ngexesha lokuguqulwa okushushu kwe-SDSS, ebonisa ukubekwa kwendawo ye-Ce kwimatrix yentsimbi endaweni ye-alloying ye-homogeneous. Nangona iimpawu zomatshini ze-SDSS zingaphuculwanga6,7, ubukho be-REE bunciphisa ubungakanani bokubandakanywa kwaye kucatshangelwa ukucinezela i-pitting kwimvelaphi54.
Ekugqibeleni, lo msebenzi ubonisa umphumo we-heterogeneity yomhlaba kwi-corrosion ye-2507 SDSS eguqulelwe nge-cerium ngokulinganisa umxholo wekhemikhali we-nanoscale components. Siphendule umbuzo wokuba kutheni i-corrodes yensimbi engenastainless naxa igqunywe ngumaleko we-oxide okhuselayo ngokufunda ngobungakanani be-microstructure, i-chemical state of surface features and signal processing usebenzisa i-K-means clustering. Kuye kwasekwa ukuba iziqithi ze-Fe3 + ezicebileyo, ezibandakanya ukulungelelaniswa kwe-octahedral kunye ne-tetrahedral kulo lonke isakhiwo somxube we-Fe2 +/Fe3 +, ngumthombo wokutshatyalaliswa kwefilimu ye-oxide kunye nomthombo wokugqwala kwe-SDSS epholileyo. I-Nanoislands elawulwa yi-Fe3 + ikhokelela ekuxhathiseni ukonakala kwe-corrosion naxa kukho i-stoichiometric eyaneleyo ye-Cr2O3 passivating layer. Ukongeza kwinkqubela phambili yemethodological eyenziwe ekumiseleni isiphumo se-nanoscale chemical heterogeneity kwi-corrosion, umsebenzi okhoyo ulindeleke ukuba ukhuthaze iinkqubo zobunjineli ukuphucula ukuxhathisa ukubola kweentsimbi ezingenasici ngexesha lentsimbi.
Ukulungiselela i-Ce-2507 SDSS ingots esetyenziswe kolu phando, amacandelo axubeneyo, kuquka i-Fe-Ce master alloy etywinwe ngeetyhubhu zentsimbi ecocekileyo, zanyibilika kwi-150 kg ye-medium frequency induction eziko ukuvelisa intsimbi etyhidiweyo kwaye igalelwe kwi-molding mold. Ukwakheka kweekhemikhali ezilinganisiweyo (wt%) zidweliswe kwiTheyibhuli eyoNgezelelweyo yesi-2. I-ingot iqala ibeshushu ibunjwe ibe ziibhloko. Emva koko insimbi yaxutywa kwi-1050 ° C imizuzu engama-60 kwisisombululo esiqinileyo, kwaye yacinywa emanzini kwiqondo lokushisa. Iisampulu ezifundiweyo zaphononongwa ngokweenkcukacha kusetyenziswa iTEM kunye ne-DOE ukufunda izigaba, ubungakanani beenkozo kunye nemorphology. Ulwazi oluthe vetshe malunga neesampuli kunye nenkqubo yokuvelisa inokufumaneka kweminye imithombo6,7.
Iisampuli zenkqubo ye-cylindrical (φ10 mm × 15 mm) ngokucinezela okutshisayo kunye ne-axis ye-cylinder parallel ukuya kwi-deformation direction yebhloko. Uxinzelelo oluphezulu lweqondo lokushisa lwenziwa kwinqanaba loxinzelelo oluqhubekayo kwi-0.01-10 s-1 kumaqondo okushisa ahlukeneyo kwi-1000-1150 ° C usebenzisa i-Gleeble-3800 simulator ye-thermal. Ngaphambi kokuguqulwa, iisampulu zifudunyezwe kwiqondo lokushisa elikhethiweyo kwizinga le-10 ° C s-1 kwi-2 min ukuphelisa i-gradient yeqondo lokushisa. Emva kokufumana ukufana kweqondo lokushisa, iisampuli zakhubazeka kwixabiso lokwenyani loxinzelelo lwe-0.7. Emva kwe-deformation, icinywa ngokukhawuleza ngamanzi ukugcina isakhiwo esonakele. Emva koko iisampulu eziqinisiweyo zisikwe ngokuhambelana nolwalathiso loxinzelelo. Kolu phononongo luthile, sikhethe umfuziselo okhubazeke ngokwe thermally kwi-1050°C, 10 s-1 ngenxa yobulukhuni obuncinci obujongweyo obuphezulu kuneminye imizekelo7.
Ubuninzi (i-80 × 10 × 17 mm3) iisampulu ze-Ce-2507 isisombululo esiluqilima zavavanywa kwisigaba esithathu se-asynchronous two-roll deformation machine LG-300, eyabonelela ngeempawu ezingcono kakhulu zoomatshini phakathi kwazo zonke ezinye iiklasi ze-deformation6. Izinga loxinzelelo kunye nokunciphisa ubukhulu be-0.2 m·s-1 kunye ne-5% kwindlela nganye, ngokulandelanayo.
Indawo yokusebenzela ye-electrochemical ye-Autolab PGSTAT128N yasetyenziselwa ukulinganisa i-SDSS ngokwe-electrochemically emva kokuqengqeleka okubandayo ukuya kuma-90% okucutha ubukhulu (1.0 elingana noxinzelelo lokwenyani) kunye noxinzelelo olushushu ukuya ku-0.7 uhlobo lokwenyani kwi-1050 oC kunye ne-10 s-1. Indawo yokusebenzela ineseli ye-electrode emithathu ene-calomel electrode egcweleyo njenge-electrode yereferensi, i-graphite counter electrode, kunye nesampuli ye-SDSS njenge-electrode esebenzayo. Iisampuli zinqunywe kwiisilinda ezinobubanzi be-11.3 mm, ukuya emacaleni apho iingcingo zobhedu zathengiswa. Emva koko isampuli yagalelwa nge-epoxy resin, ishiya indawo evulekileyo yokusebenza ye-1 cm2 njenge-electrode esebenzayo (umphezulu ongezantsi wesampulu ye-cylindrical). Sebenzisa ukhathalelo ngexesha lokunyanga i-epoxy kunye nangexesha lesanti elandelayo kunye nokupolisha ukuphepha ukuqhekeka. Indawo esebenzayo igqitywe kwaye iphuculwe nge-diamond polishing suspension ene-particle ye-micron ye-1, ihlanjululwe ngamanzi adibeneyo kunye ne-ethanol kwaye yomiswe emoyeni obandayo. Ngaphambi kwemilinganiselo ye-electrochemical, iisampulu ezikhazimlisiweyo zavezwa emoyeni kangangeentsuku ezininzi ukwenza ifilimu yendalo ye-oxide. Isisombululo se-aqueous se-FeCl3 (6.0 wt.%), esizinzile nge-HCl ukuya kwi-pH = 1.0 ± 0.01, sisetyenziselwe ukukhawulezisa ukubola kwensimbi engenasici55, ekubeni ifunyenwe kwiindawo ezinobundlobongela apho i-ion chloride ikhona ngamandla oxidizing anamandla kunye ne-pH ephantsi njengoko kucacisiwe yi-ASTM. Imigangatho ecetywayo yi-G48 kunye ne-A923. Iisampulu zantywiliselwa kwisisombululo sovavanyo lweyure eli-1 ngaphambi kokuba kuthathwe nayiphi na imilinganiselo ukuze kufikeleleke kwindawo ekufutshane nendawo yokumisa. Ukufumana isisombululo esiqinileyo, i-specimens eshushu-esebenzayo kunye ne-cold-rolled, i-impedance measurement range frequency yi-1 × 105 ~ 0.1 Hz, kunye ne-open-circuit potential (OPS) yi-5 mV, eyayiyi-0.39, 0.33, kunye ne-0.25 VSCE, ngokulandelanayo. Uvavanyo ngalunye lwe-electrochemical lwalo naluphi na isampulu luphindwe ubuncinane kathathu phantsi kweemeko ezifanayo ukuze kuqinisekiswe ukuveliswa kwakhona kwedatha.
Kwimilinganiselo ye-HE-SXRD, i-1 × 1 × 1.5 mm3 iibhloko zensimbi ze-rectangular duplex zilinganiswe kumgca we-Brockhouse wiggler wamandla aphezulu kwi-CLS, eCanada ukulinganisa ukubunjwa kwesigaba56. Ukuqokelela idatha kuqhutywe kwiqondo lokushisa kwegumbi kwi-geometry ye-Debye-Scherrer okanye ijometri yokuthutha. Ubude bobude bee-X-reyi ezilungelelaniswe kwi-Calibrant ye-LaB6 yi-0.212561 Å, ehambelana ne-58 keV, ephezulu kakhulu kune-Cu Kα (8 keV) esetyenziswa ngokuqhelekileyo njengomthombo we-X-reyi elebhu. Isampuli ibekwe kumgama we-740 mm ukusuka kumtshini. Umthamo wokufumanisa isampuli nganye ngu-0.2 × 0.3 × 1.5 mm3, ochongwa ngubukhulu be-beam kunye nobukhulu besampulu. Nganye kwezi datha yaqokelelwa kusetyenziswa i-Perkin Elmer detector yendawo, i-flat panel X-ray detector, i-200 µm pixels, 40 × 40 cm2, kusetyenziswa ixesha lokubonisa i-0.3 imizuzwana kunye nefreyimu eyi-120.
Imilinganiselo ye-X-PEEM yeenkqubo ezimbini zemodeli ezikhethiweyo zenziwa kwisikhululo sokugqibela se-PEEM somgca we-Beamline MAXPEEM kwi-laboratory ye-MAX IV (eLund, eSweden). Iisampulu zalungiswa ngendlela efanayo nemilinganiselo ye-electrochemical. Iisampulu ezilungisiweyo zigcinwe emoyeni iintsuku ezininzi kwaye zihlanjululwe kwigumbi le-vacuum ye-ultrahigh ngaphambi kokuba zihlanjululwe ngeefotoni ze-synchrotron. Isisombululo samandla sobhobhosi sifunyenwe ngokulinganisa i-ion output spectrum ukusuka kwi-N 1 s ukuya kwi-1 \ (\ pi _g ^ \st \) yendawo yokuvuselela kunye ne-hv = 401 eV kwi-N2 kunye nokuxhomekeka kwamandla e-photon kwi-E3 / 2.57. ISpectral fit inike ΔE (spectral linewidth) ~0.3 eV phezu koluhlu lwamandla olulinganisiweyo. Ngoko ke, isisombululo samandla e-beamline sasiqikelelwa ukuba yi-E / ∆E = 700 eV / 0.3 eV> 2000 kunye ne-flux ≈1012 ph / s ngokusebenzisa i-monochromator ye-SX-700 elungisiweyo kunye ne-Si 1200-line mm-1 grating ye-Fe 2p, i-L2p L2, i-Cr32pdge, i-Cr32, i-Cr32 edge L2,3 edge, kunye Ce M4,5 edge. Ngoko ke, isisombululo samandla e-beamline sasiqikelelwa ukuba yi-E / ∆E = 700 eV / 0.3 eV > 2000 kunye ne-flux ≈1012 ph / s ngokusebenzisa i-monochromator ye-SX-700 elungisiweyo kunye ne-Si 1200-line mm-1 grating ye-Fe 2p, i-L2.2pdge L2. L2.3 edge, kunye 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 Ngaloo ndlela, isisombululo samandla somzila we-beam siqikelelwe njenge-E / ∆E = 700 eV / 0.3 eV> 2000 kunye ne-flux ≈1012 f / s usebenzisa i-monochromator ye-SX-700 elungisiweyo kunye ne-Si grating ye-1200 imigca / mm ye-Fe edge 2p L2, 3p edge 2, 3p Cr2 edge. kunye neCe 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 1200 线mm−1 光栅用于Fe 2p L2,3 边缘、Cr 2p L2,3 边缘、Ni 2p L2,3 边缘和Ce M4,5 边缘.因此 , 光束线 能量 分辨率 为为為 δe = 700 EV/0.3 EV> 2000 kunye ≈1012 PH/S 通通逕 和改进00 SX 1200 线 mm-1 光栅 于 Fe 2P 2P 2P L2.3 边缘、Cr 2p L2.3 边缘、Ni 2p L2.3 边缘和Ce M4.5 边缘.Ngaloo ndlela, xa usebenzisa i-monochromator ye-SX-700 elungisiweyo kunye nomgca we-1200 we-Si grating. 3, Cr edge 2p L2.3, Ni edge 2p L2.3 kunye Ce edge M4.5.Yandisa amandla e-photon kumanyathelo e-0.2 eV. Kumandla ngamnye, imifanekiso ye-PEEM irekhodwe kusetyenziswa i-TVIPS F-216 CMOS detector ene-2 ​​x 2 binning fibre optic connection ebonelela nge-1024 × 1024 pixels kwi-20 µm field of view. Ixesha lokuvezwa kwemifanekiso yimizuzwana eyi-0.2, i-avareji ye-16 izakhelo. Amandla omfanekiso we-photoelectron akhethwe ngendlela yokubonelela ngowona mqondiso uphezulu we-electron yesibini. Yonke imilinganiselo yenziwa kwiziganeko eziqhelekileyo ze-linearly polarized photon beam. Ngolwazi oluthe vetshe ngemilinganiselo, jonga isifundo sangaphambili58. Emva kokufunda i-electron yield ye-electron (TEY) imodi yokufumanisa i-59 kunye nokusetyenziswa kwayo kwi-X-PEEM, ubunzulu bokubona le ndlela buqikelelwa kwi ~ 4-5 nm ye-Cr signal kunye ne-~ 6 nm ye-Fe signal. Ubunzulu be-Cr busondele kakhulu kubukhulu befilimu ye-oxide (~ 4 nm) 60,61 ngelixa ubunzulu be-Fe bukhulu kunobunzima befilimu ye-oxide. I-XAS eqokelelwe kufuphi ne-Fe L edge ngumxube we-iron oxide XAS kunye ne-FeO evela kwi-matrix. Kwimeko yokuqala, ukuqina kwee-electron ezikhutshwayo kungenxa yazo zonke iintlobo zee-electron ezinokuthi zibe negalelo kwi-TEY. Nangona kunjalo, isignali yentsimbi ecocekileyo ifuna amandla aphezulu e-kinetic ukuze ii-electron zidlule kuluhlu lwe-oxide, zifike kumphezulu, kwaye ziqokelelwe ngumhlalutyi. Kule meko, i-signal ye-Fe0 ibangelwa ikakhulu kwii-electron ze-LVV Auger kunye nee-electron zesibini ezikhutshwe ngabo. Ukongeza, ukuqina kwe-TEY okuba negalelo kwezi electron zibola ngexesha le-electron yokuphunyuka kwindlela49 yokunciphisa ngakumbi utyikityo lwe-Fe0 kwimephu ye-iron XAS.
Ukudibanisa i-data mining kwii-cubes zedatha (idatha ye-X-PEEM) yinyathelo eliphambili ekukhupheni ulwazi olufanelekileyo (iikhemikhali okanye iipropati ezibonakalayo) ngeendlela ezininzi. I-K-ithetha ukuhlanganisana isetyenziswa kakhulu kwiindawo ezininzi, kubandakanywa umbono womatshini, ukusetyenzwa kwemifanekiso, ukuqondwa kwepateni okungajongwanga, ubukrelekrele bokwenziwa, kunye nohlalutyo lokuhlela24. Ngokomzekelo, i-K-ithetha ukuhlanganisana isetyenziswe kakuhle ekuhlanganiseni idatha yomfanekiso we-hyperspectral62. Ngokomgaqo, kwidatha yezinto ezininzi, i-algorithm ye-K-ithetha iyakwazi ukuhlanganisana ngokulula ngokolwazi malunga neempawu zabo (iimpawu zamandla efoton). I-K-ithetha ukuhlanganisana yi-algorithm ephindaphindwayo yokwahlulahlula idatha kumaqela e-K angahambelaniyo (amaqela), apho ipixel nganye iyeyeqela elithile ngokuxhomekeke kulwabiwo lwesithuba lwemichiza yokungahoywanga kwimichiza kwimikrozo yentsimbi. I-algorithm ye-K inamanyathelo amabini: inyathelo lokuqala libala i-K centroids, kwaye inyathelo lesibini labela inqaku ngalinye kwi-cluster ene-centroids engabamelwane. Umbindi womxhuzulane weqela uchazwa njenge-arithmetic mean yamanqaku edatha (XAS spectra) yelo qela. Kukho imigama eyahlukeneyo yokuchaza iicentroids ezingabamelwane njengemigama ye-Euclidean. Kumfanekiso wegalelo we px,y (x kunye no y zisisombululo kwiipixels), CK ngumbindi womxhuzulane weqela; lo mfanekiso ungahlulwa (udityaniswe) ube ngamaqela e-K usebenzisa i-K-means63. Amanyathelo okugqibela e-K-indlela yokuhlanganisa algorithm ngala:
Inyathelo 2. Bala iqondo lobulungu bazo zonke pixels ngokwecentroid yangoku. Umzekelo, ibalwa ukusuka kumgama we-Euclidean d phakathi kombindi kunye nepikseli nganye:
Inyathelo lesi-3 Yabela ipikseli nganye kweyona centroid ikufutshane. Emva koko bala kwakhona izithuba ze-K centroid ngolu hlobo lulandelayo:
Inyathelo 4. Phinda inkqubo (i-equations (7) kunye (8)) de i-centroids ihlangane. Iziphumo zomgangatho weqela lokugqibela zinxulunyaniswa kakhulu nolona khetho lufanelekileyo lwe-centroids63 yokuqala. Kulwakhiwo lwedatha ye-PEEM yemifanekiso yentsimbi, ngokuqhelekileyo i-X (x × y × λ) yityhubhu yedatha ye-3D yoluhlu, ngelixa i-x kunye ne-y axes imele ulwazi lwesithuba (isisombululo se-pixel) kunye ne-λ axis ihambelana nemowudi ye-spectral yamandla yeefotoni. I-algorithm ye-K-means yayisetyenziselwa ukuphonononga imimandla enomdla kwidatha ye-X-PEEM ngokwahlula iipikseli (amaqela okanye iibhloko ezisezantsi) ngokweempawu zazo ze-spectral kunye nokukhupha eyona centroid (i-XAS spectral curve) kuhlalutyi ngalunye (iqela). Isetyenziselwa ukufunda ukuhanjiswa kwendawo, utshintsho lwembonakalo yendawo, ukuziphatha kwe-oxidation kunye nemeko yeekhemikhali. Ngokomzekelo, i-algorithm yokudibanisa i-K isetyenziselwa i-Fe L-edge kunye ne-Cr L-edge imimandla kwiindawo ezishushu ezisebenzayo kunye ne-X-PEEM ebandayo. Amanani ahlukeneyo eqela le-K (imimandla ye-microstructural) yavavanywa ukufumana awona maqela angcono kunye neecentroids. Xa igrafu ibonisiwe, ii-pixels zikwabelwa ngokutsha kwi-cluster centroids echanekileyo. Ukuhanjiswa kombala ngamnye kuhambelana nombindi weqela, ebonisa ukucwangciswa kwendawo yezinto zekhemikhali okanye ezibonakalayo. I-centroids ekhutshiweyo yindibaniselwano yomgca ye-spectra ecocekileyo.
Idatha exhasa iziphumo zolu phononongo iyafumaneka kumbhali weNtshona Koloni ngokwesicelo esinengqiqo.
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