CoCrFeNi yog ib qho kev kawm zoo ntawm lub ntsej muag-centered cubic (fcc) high-enttropy alloy (HEA) nrog rau kev ua tau zoo heev tab sis tsis muaj zog. Lub hom phiaj ntawm txoj kev tshawb no yog txhawm rau txhim kho qhov sib npaug ntawm lub zog thiab kev ua haujlwm ntawm cov HEAs los ntawm kev ntxiv cov nyiaj sib txawv ntawm SiC siv txoj kev arc melting. Nws tau raug tsim los tias muaj chromium nyob rau hauv lub hauv paus HEA ua rau lub decomposition ntawm SiC thaum melting. Yog li, kev sib cuam tshuam ntawm cov pa roj carbon dawb nrog chromium ua rau hauv qhov chaw tsim ntawm chromium carbides, thaum dawb silicon tseem nyob hauv cov tshuaj hauv lub hauv paus HEA thiab / lossis cuam tshuam nrog cov ntsiab lus uas ua rau lub hauv paus HEA los tsim silicides. Raws li SiC cov ntsiab lus nce, cov theem microstructure hloov hauv cov kab ke hauv qab no: fcc → fcc + eutectic → fcc + chromium carbide flakes → fcc + chromium carbide flakes + silicide → fcc + chromium carbide flakes + silicide + graphite balls / graphite flakes. Cov khoom sib xyaw ua ke nthuav tawm ntau yam ntawm cov khoom siv kho tshuab (yield zog xws li 277 MPa ntawm ntau dua 60% elongation mus rau 2522 MPa ntawm 6% elongation) piv rau cov pa roj carbon monoxide thiab siab entropy alloys. Ib co ntawm cov high entropy composites tsim qhia ib tug zoo heev ua ke ntawm txhua yam khoom (yield zog 1200 MPa, elongation 37%) thiab nyob rau yav tas los unattainable cheeb tsam nyob rau hauv yield stress-elongation daim duab. Ntxiv nrog rau qhov zoo tshaj plaws elongation, lub hardness thiab yield zog ntawm HEA composites yog nyob rau hauv tib yam li bulk metallic iav. Yog li ntawd, nws ntseeg tau tias kev txhim kho ntawm high-entropy composites tuaj yeem pab ua tiav kev sib xyaw ua ke zoo heev ntawm cov cuab yeej siv rau kev siv cov txheej txheem siab heev.
Txoj kev loj hlob ntawm high entropy alloys yog ib tug cog lus tshiab lub tswv yim nyob rau hauv metallurgy1,2. High entropy alloys (HEA) tau pom nyob rau hauv ib tug xov tooj ntawm cov ntaub ntawv ib tug zoo heev ua ke ntawm lub cev thiab txhua yam khoom, nrog rau siab thermal stability3,4 superplastic elongation5,6 qaug zog resistance7,8 corrosion kuj9,10,11, zoo heev hnav tsis kam12,13,14 , 15 thiab tribological thaj chaw 15 ,16,17 txawm nyob rau ntawm qhov kub thiab txias 18,19,20,21,22 thiab txhua yam khoom ntawm qis kub 23,24,25. Kev sib xyaw ua ke zoo heev ntawm cov khoom siv kho tshuab hauv HEA feem ntau yog los ntawm plaub qhov teebmeem tseem ceeb, uas yog cov txheej txheem siab entropy26, muaj zog lattice distortion27, qeeb diffusion28 thiab cocktail effect29. HEAs feem ntau muab faib ua FCC, BCC thiab HCP hom. FCC HEA feem ntau muaj cov kev hloov pauv xws li Co, Cr, Fe, Ni thiab Mn thiab nthuav tawm cov ductility zoo heev (txawm tias qhov kub thiab txias 25) tab sis tsis muaj zog. BCC HEA feem ntau yog tsim los ntawm cov ntsiab lus siab xws li W, Mo, Nb, Ta, Ti thiab V thiab muaj lub zog siab heev tab sis tsis tshua muaj ductility thiab tsis tshua muaj zog 30.
Kev hloov kho microstructural ntawm HEA raws li machining, thermomechanical ua thiab ntxiv cov ntsiab lus tau raug tshawb xyuas kom tau txais kev sib xyaw ua ke zoo tshaj plaws ntawm cov khoom siv tshuab. CoCrFeMnNi FCC HEA yog raug rau cov yas deformation loj heev los ntawm kev kub siab torsion, uas ua rau kom muaj zog hardness (520 HV) thiab lub zog (1950 MPa), tab sis txoj kev loj hlob ntawm ib tug nanocrystalline microstructure (~ 50 nm) ua rau cov hlau brittle31. . Nws tau pom tias kev koom ua ke ntawm twinning ductility (TWIP) thiab kev hloov pauv ntawm cov yas yas (TRIP) rau hauv CoCrFeMnNi HEAs muab kev ua haujlwm zoo hardenability uas ua rau siab tensile ductility, txawm tias ntawm tus nqi ntawm qhov tseeb tensile lub zog muaj nuj nqis. Hauv qab no (1124 MPa) 32. Kev tsim cov txheej txheej microstructure (muaj cov txheej txheem nyias nyias thiab cov tub ntxhais tsis muaj qhov tsis zoo) hauv CoCrFeMnNi HEA siv kev txhaj tshuaj peening ua rau muaj zog ntxiv, tab sis qhov kev txhim kho no tau txwv rau li 700 MPa33. Hauv kev tshawb nrhiav cov ntaub ntawv nrog kev sib xyaw ua ke zoo tshaj plaws ntawm lub zog thiab ductility, kev txhim kho ntawm multiphase HEAs thiab eutectic HEAs siv ntxiv ntawm cov ntsiab lus uas tsis yog isoatomic kuj tau tshawb xyuas 34,35,36,37,38,39,40,41. Qhov tseeb, nws tau pom tias qhov kev faib tawm zoo dua ntawm cov theem nyuaj thiab mos hauv eutectic high-entropy alloys tuaj yeem ua rau muaj kev sib xyaw ua ke zoo dua ntawm lub zog thiab ductility35,38,42,43.
CoCrFeNi system yog ib qho kev kawm dav dav ib theem FCC high-entropy alloy. Cov txheej txheem no nthuav tawm cov khoom ua haujlwm nrawm nrawm44 thiab zoo heev ductility45,46 ntawm ob qho tib si qis thiab kub. Ntau qhov kev sim tau ua los txhim kho nws lub zog tsis tshua muaj zog (~ 300 MPa) 47,48 suav nrog cov nplej refinement25, heterogeneous microstructure49, nag lossis daus 50,51,52 thiab transformation-induced plasticity (TRIP)53. Grain refinement ntawm cam khwb cia lub ntsej muag-centered cubic HEA CoCrFeNi los ntawm txias txias nyob rau hauv mob hnyav nce lub zog ntawm li 300 MPa47.48 mus rau 1.2 GPa25, tab sis txo qhov poob ntawm ductility los ntawm ntau tshaj 60% mus rau 12.6%. Qhov sib ntxiv ntawm Al rau HEA ntawm CoCrFeNi ua rau muaj kev tsim ntawm heterogeneous microstructure, uas nce nws cov txiaj ntsig muaj zog rau 786 MPa thiab nws cov txheeb ze elongation txog li 22% 49. CoCrFeNi HEA tau ntxiv nrog Ti thiab Al los ua precipitates, yog li tsim los nag kom muaj zog, ua rau nws lub zog tawm los rau 645 MPa thiab elongation mus rau 39% 51. Lub TRIP mechanism (lub ntsej muag-centered cubic → hexahedral martensitic transformation) thiab twinning nce lub tensile lub zog ntawm CoCrFeNi HEA rau 841 MPa thiab elongation ntawm tawg mus rau 76% 53.
Kev sim tau kuj tau ua los ntxiv cov khoom siv dag zog ntxiv rau HEA lub ntsej muag lub hauv paus cubic matrix los tsim cov khoom siv siab entropy uas tuaj yeem pom muaj kev sib xyaw ua ke zoo dua ntawm lub zog thiab ductility. Composites nrog siab entropy tau ua tiav los ntawm lub tshuab nqus tsev arc melting44, mechanical alloying45,46,47,48,52,53, spark plasma sintering46,51,52, nqus kub pressing45, kub isostatic pressing47,48 thiab kev loj hlob ntawm additive manufacturing processes43, 50. Carbides, oxides thiab nitrides xws li WC44, 45, 46, Al2O347, SiC48, TiC43, 49, TiN50 thiab Y2O351 tau siv los ua cov khoom siv dag zog hauv kev txhim kho HEA composites. Xaiv txoj cai HEA matrix thiab ceramic yog ib qho tseem ceeb tshwj xeeb tshaj yog thaum tsim thiab tsim kom muaj zog thiab ruaj khov HEA composite. Hauv txoj haujlwm no, CoCrFeNi raug xaiv los ua cov khoom siv matrix. Ntau yam ntawm SiC tau ntxiv rau CoCrFeNi HEA thiab lawv cov txiaj ntsig ntawm microstructure, theem muaj pes tsawg leeg, thiab cov khoom siv tshuab tau kawm.
High-purity hlau Co, Cr, Fe, thiab Ni (99.95 wt %) thiab SiC hmoov (purity 99%, loj -400 mesh) nyob rau hauv daim ntawv ntawm cov ntsiab lus hais tau siv los ua raw khoom rau kev tsim HEA composites. Lub isoatomic muaj pes tsawg leeg ntawm CoCrFeNi HEA yog thawj zaug muab tso rau hauv ib lub hemispherical dej-txias tooj liab pwm, thiab ces lub chamber raug tshem tawm mus rau 3·10-5 mbar. High purity argon roj yog qhia kom ua tiav lub tshuab nqus tsev uas yuav tsum tau rau arc melting nrog cov tsis-consumable tungsten electrodes. Lub resulting ingots yog inverted thiab remelted tsib zaug kom ntseeg tau zoo homogeneity. High-entropy composites ntawm ntau yam compositions tau npaj los ntawm kev ntxiv ib tug npaum li cas ntawm SiC rau lub resulting equiatomic CoCrFeNi nyees khawm, uas yog re-homogenized los ntawm tsib-fold inversion thiab remelting nyob rau hauv txhua rooj plaub. Lub pob molded los ntawm cov txiaj ntsig tau raug txiav siv EDM rau kev sim ntxiv thiab kev ua tus cwj pwm. Cov qauv rau kev tshawb fawb microstructural tau npaj raws li cov txheej txheem metallographic. Ua ntej, cov qauv raug kuaj xyuas siv lub teeb pom kev zoo (Leica Microscope DM6M) nrog software Leica Image Analysis (LAS Phase Expert) rau kev txheeb xyuas ntau theem. Peb cov duab thaij nyob rau hauv qhov chaw sib txawv nrog thaj tsam tag nrho ntawm 27,000 µm2 raug xaiv rau kev txheeb xyuas theem. Cov kev tshawb fawb ntxiv txog cov txheej txheem microstructural, suav nrog tshuaj lom neeg muaj pes tsawg leeg thiab kev txheeb xyuas cov khoom faib, tau ua tiav ntawm lub tshuab ntsuas hluav taws xob (JEOL JSM-6490LA) nruab nrog lub zog dispersive spectroscopy (EDS). Tus cwj pwm ntawm cov qauv siv lead ua ntawm HEA composite tau ua los ntawm X-ray diffraction system (Bruker D2 theem shifter) siv CuKα qhov chaw nrog cov kauj ruam loj ntawm 0.04 °. Cov txiaj ntsig ntawm kev hloov pauv microstructural ntawm cov khoom siv kho tshuab ntawm HEA composites tau kawm siv Vickers microhardness tests thiab compression tests. Rau qhov kev sim hardness, load ntawm 500 N yog thov rau 15 s siv tsawg kawg yog 10 indentations rau ib tus qauv. Kev ntsuas compression ntawm HEA composites nyob rau hauv chav tsev kub tau ua nyob rau hauv cov duab plaub (7 mm × 3 mm × 3 mm) ntawm Shimadzu 50KN universal testing machine (UTM) ntawm tus nqi pib ntawm 0.001 / s.
High entropy composites, hauv qab no hu ua cov qauv S-1 rau S-6, tau npaj los ntawm kev ntxiv 3%, 6%, 9%, 12%, 15%, thiab 17% SiC (tag nrho los ntawm qhov hnyav%) rau CoCrFeNi matrix . raws. Cov qauv siv uas tsis muaj SiC ntxiv yog nyob rau hauv qab no hu ua qauv S-0. Optical micrographs ntawm cov tsim HEA composites muaj nyob rau hauv daim duab. 1, qhov twg, vim muaj ntau yam additives, ib-theem microstructure ntawm CoCrFeNi HEA tau hloov mus rau hauv microstructure uas muaj ntau theem nrog txawv morphology, qhov ntau thiab tsawg, thiab kev faib tawm. Tus nqi ntawm SiC hauv qhov muaj pes tsawg leeg. Tus nqi ntawm txhua theem tau txiav txim siab los ntawm cov duab tsom xam siv LAS Phase Expert software. Lub inset rau daim duab 1 (sab sauv sab xis) qhia qhov piv txwv cheeb tsam rau qhov kev tshuaj ntsuam no, nrog rau thaj tsam feem ntawm txhua theem.
Optical micrographs ntawm tsim high-entropy composites: (a) C-1, (b) C-2, (c) C-3, (d) C-4, (e) C-5 thiab (f) C- 6. Lub inset qhia ib qho piv txwv ntawm qhov sib piv-raws li cov duab theem tsom xam tau siv LAS Phase Expert software.
Raws li qhia hauv daim duab. 1a, eutectic microstructure tsim los ntawm cov matrix ntim ntawm C-1 composite, qhov twg tus nqi ntawm matrix thiab eutectic theem yog kwv yees li 87.9 ± 0.47% thiab 12.1% ± 0.51%, feem. Nyob rau hauv lub composite (C-2) qhia nyob rau hauv daim duab 1b, tsis muaj cov cim qhia ntawm ib tug eutectic tshuaj tiv thaiv thaum lub sij hawm solidification, thiab ib tug microstructure txawv kiag li ntawm cov C-1 composite yog pom. Lub microstructure ntawm C-2 composite yog qhov zoo thiab muaj cov phaj nyias (carbides) sib npaug faib rau hauv matrix theem (fcc). Qhov ntim feem ntawm cov matrix thiab carbide yog kwv yees li ntawm 72 ± 1.69% thiab 28 ± 1.69%, feem. Ntxiv nrog rau cov matrix thiab carbide, ib theem tshiab (silicide) tau pom nyob rau hauv C-3 composite, raws li qhia nyob rau hauv daim duab 1c, qhov twg lub ntim feem ntawm xws li silicide, carbide, thiab matrix theem yog kwv yees li ntawm 26.5% ± 0.41%, 25.9 ± 0.53, thiab 47.6 ± 0.34, feem. Lwm theem tshiab (graphite) kuj tau pom nyob rau hauv microstructure ntawm C-4 composite; tag nrho ntawm plaub theem tau txheeb xyuas. Cov theem graphite muaj qhov sib txawv globular zoo nrog qhov sib txawv tsaus nti hauv cov duab kho qhov muag thiab tsuas yog tam sim no nyob rau hauv me me (kwv yees ntim feem tsuas yog kwv yees li 0.6 ± 0.30%). Hauv kev sib xyaw C-5 thiab C-6, tsuas yog peb theem tau txheeb xyuas, thiab qhov tsaus ntuj sib txawv graphite theem hauv cov khoom sib xyaw no tshwm sim hauv daim ntawv ntawm flakes. Piv rau graphite flakes hauv Composite S-5, graphite flakes hauv Composite S-6 yog dav, luv dua, thiab ntau dua. Ib qho kev nce ntxiv hauv cov ntsiab lus graphite kuj tau pom los ntawm 14.9 ± 0.85% hauv C-5 sib xyaw mus txog 17.4 ± 0.55% hauv C-6 sib xyaw.
Txhawm rau tshawb xyuas ntxiv cov ncauj lus kom ntxaws microstructure thiab tshuaj lom neeg muaj pes tsawg leeg ntawm txhua theem hauv HEA cov khoom sib xyaw, cov qauv tau kuaj xyuas siv SEM, thiab EMF taw tes tsom xam thiab tshuaj ntsuam xyuas tshuaj. Cov txiaj ntsig rau kev sib xyaw C-1 tau qhia hauv daim duab. 2, qhov uas muaj eutectic sib tov sib cais cov cheeb tsam ntawm lub ntsiab matrix theem yog pom meej. Daim ntawv qhia tshuaj lom neeg ntawm kev sib xyaw C-1 muaj nyob rau hauv daim duab 2c, qhov twg nws tuaj yeem pom tau tias Co, Fe, Ni, thiab Si yog sib npaug ntawm cov theem matrix. Txawm li cas los xij, ib qho me me ntawm Cr tau pom nyob rau hauv theem matrix piv rau lwm cov ntsiab lus ntawm lub hauv paus HEA, qhia tias Cr diffused tawm ntawm matrix. Cov muaj pes tsawg leeg ntawm cov dawb eutectic theem nyob rau hauv daim duab SEM yog nplua nuj nyob rau hauv chromium thiab carbon, qhia tias nws yog chromium carbide. Qhov tsis muaj qhov sib cais SiC hauv microstructure, ua ke nrog cov ntsiab lus qis ntawm chromium hauv matrix thiab muaj cov eutectic sib tov uas muaj chromium-nplua nuj theem, qhia tias tag nrho decomposition ntawm SiC thaum melting. Raws li cov txiaj ntsig ntawm SiC decomposition, silicon yaj nyob rau hauv matrix theem, thiab cov pa roj carbon monoxide tsis muaj kev cuam tshuam nrog chromium los tsim chromium carbides. Raws li tuaj yeem pom, tsuas yog carbon tau txiav txim siab zoo los ntawm EMF txoj kev, thiab cov theem tsim tau lees paub los ntawm kev txheeb xyuas cov yam ntxwv carbide peaks hauv X-ray diffraction qauv.
(a) SEM duab ntawm cov qauv S-1, (b) daim duab loj, (c) daim duab qhia chaw, (d) EMF cov txiaj ntsig ntawm qhov chaw qhia.
Kev tsom xam ntawm kev sib xyaw C-2 yog qhia hauv daim duab. 3. Zoo ib yam li cov tsos mob hauv optical microscopy, SEM kev ntsuam xyuas tau nthuav tawm cov qauv zoo tsim los ntawm ob theem xwb, nrog rau lub xub ntiag ntawm nyias lamellar theem sib npaug faib thoob plaws hauv cov qauv. matrix theem, thiab tsis muaj eutectic theem. Cov khoom faib thiab EMF taw tes tsom xam ntawm lub lamellar theem tau qhia txog cov ntsiab lus siab ntawm Cr (daj) thiab C (ntsuab) nyob rau theem no, uas rov qhia txog qhov decomposition ntawm SiC thaum lub sij hawm yaj thiab kev sib cuam tshuam ntawm cov pa roj carbon monoxide tso tawm nrog cov nyhuv chromium. . VEA matrix tsim ib theem lamellar carbide. Kev faib tawm ntawm cov ntsiab lus thiab kev tsom xam ntawm theem matrix pom tias feem ntau ntawm cobalt, hlau, npib tsib xee thiab silicon muaj nyob rau hauv matrix theem.
(a) SEM duab ntawm tus qauv S-2, (b) daim duab loj, (c) daim duab qhia chaw, (d) EMF cov txiaj ntsig ntawm qhov chaw qhia.
SEM cov kev tshawb fawb ntawm C-3 composites qhia pom muaj cov theem tshiab ntxiv rau carbide thiab matrix theem. Daim duab qhia chaw (Fig. 4c) thiab EMF taw tes tsom xam (Fig. 4d) qhia tias cov theem tshiab yog nplua nuj nyob rau hauv nickel, cobalt, thiab silicon.
(a) SEM duab ntawm cov qauv S-3, (b) daim duab loj, (c) daim duab qhia chaw, (d) EMF cov txiaj ntsig ntawm qhov chaw qhia.
Cov txiaj ntsig ntawm SEM thiab EMF tsom xam ntawm C-4 sib xyaw yog pom hauv daim duab. 5. Ntxiv nrog rau peb theem tau pom nyob rau hauv kev sib xyaw C-3, kuj pom muaj cov graphite nodules. Qhov ntim feem ntawm cov qib silicon-nplua nuj kuj siab dua li ntawm C-3 composite.
(a) SEM duab ntawm tus qauv S-4, (b) daim duab loj, (c) daim duab qhia chaw, (d) EMF cov txiaj ntsig ntawm qhov chaw qhia.
Cov txiaj ntsig ntawm SEM thiab EMF spectra ntawm composites S-5 thiab S-6 yog pom nyob rau hauv daim duab 1 thiab 2. 6 thiab 7, feem. Ntxiv nrog rau ib qho me me ntawm spheres, muaj cov graphite flakes kuj tau pom. Ob tus naj npawb ntawm graphite flakes thiab qhov ntim feem ntawm silicon-muaj theem nyob rau hauv C-6 composite yog ntau dua nyob rau hauv C-5 composite.
(a) SEM duab ntawm cov qauv C-5, (b) nthuav dav, (c) daim duab qhia chaw, (d) EMF cov txiaj ntsig ntawm qhov chaw qhia.
(a) SEM duab ntawm cov qauv S-6, (b) daim duab loj, (c) daim duab qhia chaw, (d) EMF cov txiaj ntsig ntawm qhov chaw qhia.
Crystal qauv characterization ntawm HEA composites kuj tau ua los ntawm kev ntsuas XRD. Qhov tshwm sim yog pom nyob rau hauv daim duab 8. Nyob rau hauv lub diffraction qauv ntawm lub hauv paus WEA (S-0), tsuas yog cov peaks sib haum mus rau theem fcc yog pom. X-ray diffraction qauv ntawm composites C-1, C-2, thiab C-3 tau qhia tias muaj cov peaks ntxiv rau chromium carbide (Cr7C3), thiab lawv cov kev siv qis dua rau cov qauv C-3 thiab C-4, uas tau qhia. uas kuj nrog cov ntaub ntawv EMF rau cov qauv no. Peaks sib thooj rau Co/Ni silicides tau soj ntsuam rau cov qauv S-3 thiab S-4, rov ua raws li EDS daim duab qhia tau pom hauv daim duab 2 thiab 3. Raws li pom hauv daim duab 3 thiab daim duab 4. 5 thiab S-6 peaks tau pom. sib raug rau graphite.
Ob qho tib si microstructural thiab crystallographic yam ntxwv ntawm cov khoom tsim tau qhia tias decomposition ntawm SiC ntxiv. Qhov no yog vim muaj cov chromium hauv VEA matrix. Chromium muaj kev sib raug zoo heev rau cov pa roj carbon 54.55 thiab reacts nrog cov pa dawb los tsim carbides, raws li qhia los ntawm kev pom qhov txo qis hauv cov ntsiab lus chromium ntawm matrix. Si dhau mus rau theem fcc vim kev sib cais ntawm SiC56. Yog li, kev nce ntxiv ntawm SiC rau lub hauv paus HEA ua rau muaj kev nce ntxiv ntawm cov theem carbide thiab cov nyiaj Si dawb hauv microstructure. Nws tau pom tias qhov ntxiv Si no tso rau hauv matrix ntawm qhov qis qis (hauv cov khoom sib xyaw S-1 thiab S-2), thaum nyob rau hauv cov concentrations ntau dua (sib xyaw S-3 rau S-6) nws ua rau ntxiv cobalt deposition / . npib tsib xee silicide. Tus qauv enthalpy ntawm tsim ntawm Co thiab Ni silicides, tau los ntawm ncaj qha synthesis high-temperature calorimetry, yog -37.9 ± 2.0, -49.3 ± 1.3, -34.9 ± 1.1 kJ mol -1 rau Co2Si, CoSi thiab CoSi2, ntsig txog, tus nqi yog - 50.6 ± 1.7 thiab – 45.1 ± 1.4 kJ mol-157 rau Ni2Si thiab Ni5Si2, feem. Cov txiaj ntsig no qis dua qhov kub ntawm qhov tsim ntawm SiC, qhia tias kev sib cais ntawm SiC ua rau kev tsim cov Co/Ni silicides yog qhov muaj txiaj ntsig zoo. Nyob rau hauv ob qho tib si S-5 thiab S-6 composites, ntxiv silicon dawb tam sim no, uas tau absorbed tshaj qhov tsim ntawm silicide. Qhov no dawb silicon tau pom los pab txhawb rau graphitization pom nyob rau hauv cov pa steels58.
Cov cuab yeej cuab tam ntawm cov tsim ceramic-reinforced composites raws li HEA raug tshawb xyuas los ntawm kev ntsuam xyuas compression thiab hardness tests. Cov kev ntxhov siab-strain curves ntawm cov tsim composites yog qhia nyob rau hauv Fig. 9a, thiab nyob rau hauv daim duab 9b qhia ib tug scatterplot ntawm tej yield zog, yield zog, hardness, thiab elongation ntawm cov tsim composites.
(a) Compressive strain curves thiab (b) scatterplots qhia tshwj xeeb yield stress, yield zog, hardness thiab elongation. Nco ntsoov tias tsuas yog cov qauv S-0 txog S-4 tau pom, vim cov qauv S-5 thiab S-6 muaj qhov cuam tshuam loj heev.
Raws li pom hauv daim duab. 9, lub zog tawm los ntawm 136 MPa rau lub hauv paus VES (C-0) rau 2522 MPa rau C-4 composite. Piv nrog rau WPP yooj yim, S-2 composite tau pom qhov elongation zoo heev rau kev ua tsis tiav ntawm li 37%, thiab tseem pom tau tias muaj zog ntau dua qhov txiaj ntsig (1200 MPa). Kev sib xyaw ua ke zoo heev ntawm lub zog thiab kev ua kom zoo ntawm cov khoom sib xyaw no yog vim kev txhim kho hauv tag nrho microstructure, nrog rau kev faib tawm ntawm cov nplua carbide lamellae thoob plaws hauv microstructure, uas xav tias yuav cuam tshuam kev txav mus los. Cov txiaj ntsig zoo ntawm C-3 thiab C-4 composites yog 1925 MPa thiab 2522 MPa, feem. Cov txiaj ntsig zoo no tuaj yeem piav qhia los ntawm cov khoom ntim siab ntawm cov cemented carbide thiab silicide theem. Txawm li cas los xij, lub xub ntiag ntawm cov theem no kuj ua rau elongation ntawm kev tawg tsuas yog 7%. Cov kev ntxhov siab-strain curves ntawm lub hauv paus composites CoCrFeNi HEA (S-0) thiab S-1 yog convex, qhia txog kev ua kom cov nyhuv twinning lossis TRIP59,60. Piv nrog rau cov qauv S-1, qhov kev ntxhov siab-txoj kev nkhaus ntawm cov qauv S-2 muaj qhov sib sib zog nqus ntawm qhov sib txawv ntawm li 10.20%, uas txhais tau hais tias qhov kev hloov pauv ib txwm yog lub ntsiab deformation hom ntawm cov qauv hauv lub xeev deformed 60,61. . Txawm li cas los xij, tus nqi hardening nyob rau hauv cov qauv no tseem siab dhau ntawm cov kab mob loj, thiab ntawm cov kab mob ntau dua kev hloov mus rau convexity kuj pom tau (txawm tias nws tsis tuaj yeem txiav txim siab tias qhov no yog vim tsis ua haujlwm ntawm lubricated compressive loads). ). Composites C-3 thiab C-4 tsuas yog txwv plasticity vim tias muaj ntau dua ntim feem ntawm carbides thiab silicides hauv microstructure. Kev ntsuas compression ntawm cov qauv ntawm cov khoom sib xyaw C-5 thiab C-6 tsis tau ua tiav vim muaj qhov cuam tshuam loj heev ntawm cov qauv ntawm cov khoom sib xyaw (saib daim duab 10).
Stereomicrographs ntawm casting defects (qhia los ntawm cov xub liab) nyob rau hauv cov qauv ntawm composites C-5 thiab C-6.
Cov txiaj ntsig ntawm kev ntsuas qhov hardness ntawm VEA composites tau pom hauv daim duab. 9 ib b. Lub hauv paus WEA muaj hardness ntawm 130 ± 5 HV, thiab cov qauv S-1, S-2, S-3 thiab S-4 muaj hardness tus nqi ntawm 250 ± 10 HV, 275 ± 10 HV, 570 ± 20 HV thiab 755 ± 20 HV. Qhov kev nce hauv hardness tau pom zoo nrog kev hloov pauv ntawm lub zog tawm los ntawm kev sim compression thiab tau cuam tshuam nrog kev nce ntawm cov khoom sib xyaw hauv cov khoom sib xyaw. Kev suav cov txiaj ntsig tshwj xeeb raws li lub hom phiaj muaj pes tsawg leeg ntawm txhua tus qauv kuj tau qhia hauv daim duab. 9 ib b. Feem ntau, kev sib xyaw ua ke zoo tshaj plaws ntawm cov khoom muaj zog (1200 MPa), hardness (275 ± 10 HV), thiab cov txheeb ze elongation rau qhov tsis ua hauj lwm (~ 37%) raug soj ntsuam rau kev sib xyaw C-2.
Kev sib piv ntawm lub zog tawm los thiab cov txheeb ze elongation ntawm cov khoom sib xyaw nrog cov khoom sib txawv yog qhia hauv daim duab 11a. Composites raws li CoCrFeNi nyob rau hauv txoj kev tshawb no qhia tau hais tias siab elongation ntawm ib qho kev nyuaj siab theem 62. Nws tseem tuaj yeem pom tau tias cov khoom ntawm HEA cov khoom sib xyaw tsim nyob rau hauv txoj kev tshawb no yog nyob rau hauv thaj tsam yav dhau los uas tsis tau ua haujlwm ntawm cov phiaj xwm ntawm cov khoom muaj zog tiv thaiv elongation. Tsis tas li ntawd, cov khoom sib xyaw tsim muaj ntau qhov sib xyaw ua ke ntawm lub zog (277 MPa, 1200 MPa, 1925 MPa thiab 2522 MPa) thiab elongation (> 60%, 37%, 7.3% thiab 6.19%). Lub zog tawm los kuj yog qhov tseem ceeb hauv kev xaiv cov khoom siv rau kev siv engineering siab heev63,64. Nyob rau hauv no hais txog, HEA composites ntawm lub invention tam sim no muaj kev sib xyaw ua ke zoo heev ntawm cov khoom muaj zog thiab elongation. Qhov no yog vim qhov sib ntxiv ntawm qhov tsis tshua muaj SiC ua rau cov khoom sib xyaw nrog cov khoom muaj zog tshwj xeeb. Qhov tshwj xeeb yield zog thiab elongation ntawm HEA composites yog nyob rau tib yam li HEA FCC thiab refractory HEA, raws li qhia nyob rau hauv daim duab 11b. Lub hardness thiab yield zog ntawm cov tsim composites yog nyob rau hauv tib yam li rau loj loj hlau tsom iav65 (Fig. 11c). Cov tsom iav loj loj (BMS) yog cov yam ntxwv ntawm qhov tawv tawv thiab lub zog tawm los, tab sis lawv qhov elongation yog txwv 66,67. Txawm li cas los xij, qhov hardness thiab yield zog ntawm ib co ntawm cov HEA composites tsim nyob rau hauv txoj kev tshawb no kuj qhia elongation tseem ceeb. Yog li, nws tau txiav txim siab tias cov khoom sib xyaw tsim los ntawm VEA muaj qhov tshwj xeeb thiab nrhiav-tom qab ua ke ntawm cov khoom siv kho tshuab rau ntau yam kev siv cov qauv. Qhov kev sib xyaw tshwj xeeb ntawm cov khoom siv kho tshuab tuaj yeem piav qhia los ntawm cov khoom sib txawv ntawm cov carbides nyuaj tsim hauv situ hauv FCC HEA matrix. Txawm li cas los xij, raws li ib feem ntawm lub hom phiaj ntawm kev ua tiav kev sib xyaw ua ke ntawm lub zog zoo dua, cov kev hloov pauv microstructural uas tshwm sim los ntawm kev sib ntxiv ntawm cov txheej txheem ceramic yuav tsum tau ua tib zoo kawm thiab tswj kom tsis txhob muaj qhov tsis xws luag, xws li cov pom hauv S-5 thiab S-6 composites, thiab ductility. poj niam txiv neej.
Cov txiaj ntsig ntawm txoj kev tshawb fawb no tau muab piv nrog ntau yam khoom siv thiab HEAs: (a) elongation piv rau cov txiaj ntsig muaj zog 62, (b) cov txiaj ntsig tshwj xeeb kev ntxhov siab piv rau ductility63 thiab (c) yield zog piv rau hardness65.
Lub microstructure thiab mechanical zog ntawm ib tug series ntawm HEA-ceramic composites raws li HEA CoCrFeNi system nrog ntxiv ntawm SiC tau kawm thiab cov lus xaus nram qab no tau raug kos:
High entropy alloy composites tuaj yeem ua tiav los ntawm kev ntxiv SiC rau CoCrFeNi HEA siv txoj kev arc melting.
SiC decomposes thaum lub sij hawm arc melting, ua rau tsim nyob rau hauv situ ntawm carbide, silicide thiab graphite theem, muaj thiab ntim feem ntawm uas nyob ntawm seb tus nqi ntawm SiC ntxiv rau lub hauv paus HEA.
HEA composites nthuav tawm ntau yam khoom siv zoo heev, nrog rau cov khoom uas poob rau hauv cov cheeb tsam yav dhau los uas tsis muaj nyob rau ntawm lub zog tawm los piv rau cov phiaj xwm elongation. Lub zog tawm los ntawm HEA composite ua siv 6 wt% SiC yog ntau tshaj yim npaug ntawm lub hauv paus HEA thaum tuav 37% ductility.
Lub hardness thiab yield zog ntawm HEA composites yog nyob rau hauv ntau yam ntawm bulk metallic iav (BMG).
Cov kev tshawb pom qhia tias high-entropy alloy composites sawv cev rau txoj hauv kev cog lus kom ua tiav kev sib xyaw ua ke zoo heev ntawm cov khoom siv hlau-tshuab rau kev siv cov txheej txheem siab heev.
Post lub sij hawm: Lub Xya hli ntuj-12-2023