Txoj kev tshawb no tau ua tiav qhov kev npaj tswj tau ntawm L12 precipitates raws li theem daim duab suav. Ua ke nrog cov thermodynamic muaj peev xwm -pH daim duab ntawm corrosion thiab TEM kev soj ntsuam ntawm passive films, lub zog mechanism ntawm cov ntsiab lus ntawm nanoscale L12 theem ntawm corrosion ntawm high -entropy alloys tau soj ntsuam systematically. Nws tau qhia meej tias nag lossis daus ntawm nanoscale L12 theem pab txhawb Cr cov ntsiab lus hauv FCC matrix, yog li txhim kho kev ruaj ntseg ntawm cov yeeb yaj kiab tsis zoo thiab tiv thaiv kev loj hlob pitting. Ib lub tswv yim tshiab tau thov kom ua kom muaj peev xwm ua kom muaj zog ntawm siab -entropy alloys los ntawm precipitating nanoscale L12 theem.
Daim duab piav qhia
Daim duab qhia theem ntawm L12- siab entropy alloys muab cov kev taw qhia raug rau kev tswj tau ntawm nag lossis daus-lub zog siab entropy alloys. Raws li pom nyob rau hauv daim duab 1a, lub Co20Cr15Fe20Ni33Al6Ti6 alloy exhibits ib tug yooj yim FCC + L12 qauv nyob rau hauv ib tug dav kub ntau yam ntawm 800-1100 degree, zam lub tsim ntawm B2 thiab Sigma theem. Los ntawm kev sib txuas cov duab 1a thiab 1b, qhov loj ntawm L12 theem tuaj yeem tswj tau qhov tseeb thaum sib txawv nws cov ntsiab lus. Cov duab 1c thiab 1d kwv yees qhov kev hloov pauv hauv cov txheej txheem hauv FCC thiab L12 theem ua haujlwm ntawm qhov kub thiab txias, uas tej zaum yuav yog qhov laj thawj tseem ceeb rau kev hloov pauv ntawm cov hlau alloy qhov corrosion kuj.
Cov ntsiab lus tseem ceeb 2: Corrosion Behavior ntawm L12 Phase Reinforced High-Entropy Alloys. Daim duab 2a-b qhia tau hais tias raws li cov ntsiab lus ntawm L12 theem nce, pitting corrosion muaj peev xwm ntawm cov alloy ho nce, nce mus txog kwv yees li 600 mV SCE. Piv nrog rau lwm cov multiphase siab-entropy alloys lossis cov khoom siv ib txwm siv, cov hlau no nthuav tawm cov txiaj ntsig tseem ceeb ntawm nws txoj kev tiv thaiv corrosion tsis zoo thiab pitting corrosion (Daim duab 2c).
Point 3: Thermodynamic stability ntawm oxide ntawm ob-theem nto yog soj ntsuam los ntawm qhov muaj peev xwm -pH daim duab. Daim duab 3a-b raws li qhia tau hais tias qhov ntsuas kub zoo ntawm kev tsim oxide nyob rau ntawm qhov chaw ntawm FCC theem thiab L12 theem. Cov oxide tsim nyob rau saum npoo ntawm FCC theem yog feem ntau Cr2O3, thaum lub oxide tsim nyob rau saum npoo ntawm L12 theem yog Al2O3. Cr2O3 muaj zog tiv thaiv pitting corrosion, thaum Al2O3 yooj yim adsorbed thiab eroded los ntawm Cl- nyob rau hauv cov tshuaj chloride{18}}muaj cov tshuaj, yog li muaj ib tug tsis muaj zog tiv thaiv pitting corrosion. Yog li, nws tuaj yeem txiav txim siab tias L12 theem muaj kev cuam tshuam ntau dua rau corrosion piv rau FCC theem.
Point 4: TEM kev soj ntsuam ntawm cov yeeb yaj kiab passivation tau lees paub qhov kev twv ua ntej thermodynamic. Daim duab 4a-f qhia tias L12 theem tau zoo dua corroded thaum lub sij hawm corrosion, tab sis cov zaj duab xis passivation tau loj hlob sai raws li qhov qis FCC matrix, tsim ib qho nkhaus tab sis txuas mus ntxiv thiab cov yeeb yaj kiab passivation. Cov txiaj ntsig no tau ua raws li kev kwv yees ntawm qhov muaj peev xwm -pH daim duab. Ntxiv mus, qhov ruaj khov ntawm cov yeeb yaj kiab alloy passivation feem ntau cuam tshuam nrog cov khoom ntawm FCC matrix, thiab siab dua cov ntsiab lus Cr hauv FCC matrix, qhov ruaj khov dua cov yeeb yaj kiab passivation. Yog li ntawd, los ntawm kev nce cov ntsiab lus ntawm L12 theem thiab txhawb kev txhawb nqa ntawm Cr cov ntsiab lus hauv FCC matrix (Daim duab 1c), kev ruaj ntseg ntawm cov yeeb yaj kiab passivation tuaj yeem txhim kho tau zoo.
Cov ntsiab lus 5: Kev soj ntsuam kev loj hlob ruaj khov ntawm Pitting Corrosion Piv txwv tias L12 theem yog yaj tag, puas yuav cov sub- ruaj khov "qhov" seem tom qab kev tawg txuas ntxiv mus ntxiv lossis rov ua dua tshiab? Daim duab 5a qhia cov txheej txheem electrochemical tshwm sim nyob rau hauv sub-pitting corrosion pits ruaj khov. Ntawm no, seb lub pitting tuaj yeem loj hlob ruaj khov nyob ntawm kev sib tw ntawm kev sib cais kinetics thiab diffusion kinetics. Rau tib qhov me me sub- ruaj khov pitting corrosion pits, idiff, crit yuav tsum nyob tas li, raws li qhia los ntawm kab xiav hauv daim duab 5b, thaum FCC matrixes nrog cov ntsiab lus Cr sib txawv yuav ua rau muaj kev hloov pauv tseem ceeb hauv kev sib cais kinetics, raws li qhia los ntawm kab liab hauv daim duab 5b. Qhov siab dua cov ntsiab lus Cr hauv FCC matrix, qhov qis dua ntawm txoj kab nqes ntawm qhov tam sim no ceev piv rau qhov muaj peev xwm, yog li yuav tsum muaj qhov tseem ceeb dua rau kev loj hlob ruaj khov ntawm pitting corrosion, uas ua rau muaj kev tiv thaiv kom ruaj khov ntawm pitting corrosion.
Qhov no ua haujlwm tau zoo txhim kho qhov kev tiv thaiv corrosion ntawm nag lossis daus - ntxiv dag zog rau siab -enttropy alloy los ntawm kev tswj cov ntsiab lus ntawm L12 theem. Cov yam ntxwv kev faib tawm ntawm cov ntsiab lus thaum nag lossis daus ntawm L12 theem tau nkag siab, qhov cuam tshuam ntawm cov ntsiab lus ntawm cov theem nag lossis daus ntawm kev ua haujlwm corrosion ntawm high -entropy alloy tau qhia meej, thiab cov txheej txheem ntawm kev cuam tshuam ntawm L12 theem cov ntsiab lus ntawm kev ruaj ntseg ntawm cov zaj duab xis passivation thiab cov txheej txheem kev loj hlob ntawm pitting corrosion yog elucidated.