I-CoCrFeNi iyi-cubic (fcc) ephezulu ye-entropy alloy (HEA) efundwe kahle ene-ductility enhle kakhulu kodwa amandla alinganiselwe. Ukugxila kwalolu cwaningo kukuthuthukisa ibhalansi yamandla kanye ne-ductility yalawo ma-HEA ngokungeza amanani ahlukene e-SiC kusetshenziswa indlela yokuncibilika kwe-arc. Kuye kwatholakala ukuthi ukuba khona kwe-chromium ku-HEA eyisisekelo kubangela ukubola kwe-SiC ngesikhathi sokuncibilika. Ngakho-ke, ukusebenzisana kwekhabhoni yamahhala ne-chromium kuholela ekwakhekeni kwe-in situ kwe-chromium carbides, kuyilapho i-silicon yamahhala ihlala isixazululo kusisekelo se-HEA kanye/noma isebenzisana nezakhi ezenza isisekelo se-HEA ukuze zenze ama-silicides. Njengoba okuqukethwe kwe-SiC kukhula, isigaba se-microstructure sishintsha ngokulandelana okulandelayo: fcc → fcc + eutectic → fcc + chromium carbide flakes → fcc + chromium carbide flakes + silicide → fcc + chromium carbide flakes + silicide + graphite balls / graphite flakes. Izinhlanganisela eziwumphumela zibonisa uhla olubanzi kakhulu lwezakhiwo zemishini (amandla esivuno asukela ku-277 MPa ngaphezu kobude obungama-60% ukuya ku-2522 MPa ngobude obungu-6%) uma kuqhathaniswa nama-alloys avamile nama-entropy alloys aphezulu. Ezinye zezinhlanganisela eziphezulu ze-entropy ezithuthukisiwe zibonisa inhlanganisela enhle kakhulu yezakhiwo zemishini (isivuno samandla angu-1200 MPa, ubude obungama-37%) futhi zithatha izifunda ebezingafinyeleleki ngaphambilini kumdwebo wokukhulisa ukucindezeleka kwesivuno. Ngaphezu kobude obumangalisayo, ubulukhuni namandla esivuno sezinhlanganisela ze-HEA zikububanzi obufanayo nezingilazi zensimbi eziyinqwaba. Ngakho-ke, kukholakala ukuthi ukuthuthukiswa kwezinhlanganisela eziphezulu ze-entropy kungasiza ukuzuza inhlanganisela enhle kakhulu yezakhiwo zemishini yezinhlelo zokusebenza ezithuthukisiwe zesakhiwo.
Ukuthuthukiswa kwama-alloys aphezulu e-entropy kuwumqondo omusha othembisayo ku-metallurgy1,2. Ama-alloys aphezulu e-entropy (i-HEA) abonise ezimweni eziningi inhlanganisela enhle kakhulu yezakhiwo zomzimba nemishini, kuhlanganise nokuzinza okuphezulu kokushisa3,4 i-superplastic elongation5,6 ukumelana nokukhathala7,8 ukumelana nokugqwala9,10,11, ukumelana okuhle kakhulu kokugqoka12,13,14 ,15 kanye nezakhiwo ze-tribological15 ,16,17 ngisho emazingeni okushisa aphezulu18,19,20,21,22 kanye nemishini izakhiwo emazingeni okushisa aphansi23,24,25. Inhlanganisela enhle kakhulu yezakhiwo zemishini ku-HEA imvamisa kuthiwa ngenxa yemiphumela emine eyinhloko, okuyi-entropy26 ephezulu yokucushwa, i-lattice distortion eqinile27, i-slow diffusion28 kanye ne-cocktail effect29. Ama-HEA ngokuvamile ahlukaniswa njengezinhlobo ze-FCC, BCC kanye ne-HCP. I-FCC HEA ngokuvamile iqukethe izinto zoshintsho ezifana ne-Co, Cr, Fe, Ni ne-Mn futhi ibonisa i-ductility enhle kakhulu (ngisho nasezingeni eliphansi lokushisa elingu-25) kodwa amandla aphansi. I-BCC HEA ivamise ukwakhiwa ngezakhi zokuminyana okuphezulu njenge-W, Mo, Nb, Ta, Ti kanye no-V futhi inamandla amakhulu kakhulu kodwa i-ductility ephansi namandla athile aphansi30.
Ukuguqulwa kwe-microstructural ye-HEA okusekelwe kumishini, ukucutshungulwa kwe-thermomechanical kanye nokwengezwa kwezinto kuye kwaphenywa ukuze kutholwe inhlanganisela engcono kakhulu yezakhiwo zemishini. I-CoCrFeMnNi i-FCC HEA ingaphansi kokuguqulwa okunzima kwepulasitiki nge-high-pressure torsion, okuholela ekwenyukeni okukhulu kokuqina (520 HV) namandla (1950 MPa), kodwa ukuthuthukiswa kwe-nanocrystalline microstructure (~50 nm) kwenza i-alloy brittle31 . Kutholwe ukuthi ukufakwa kwe-twinning ductility (TWIP) kanye ne-plasticity induced (TRIP) ibe yi-CoCrFeMnNi HEAs kunikeza ukuqina okuhle komsebenzi okuholela ekuqineni okuphezulu, nakuba ngenani lamanani wangempela wamandla aqinile. Ngezansi (1124 MPa) 32. Ukwakheka kwe-microstructure enezingqimba (ehlanganisa ungqimba oluncane olugogekile kanye nengqikithi engashintshile) ku-CoCrFeMnNi HEA kusetshenziswa i-shot peening kuholele ekwenyukeni kwamandla, kodwa lokhu kuthuthukiswa kukhawulelwe kuma-MPa33 angaba ngu-700. Ekufuneni izinto ezinokuhlanganiswa okuhle kakhulu kwamandla kanye ne-ductility, ukuthuthukiswa kwama-HEA e-multiphase kanye ne-eutectic HEAs kusetshenziswa izengezo zezinto ezingezona ze-isoatomic nakho kuye kwaphenywa34,35,36,37,38,39,40,41. Ngempela, kutholakale ukuthi ukusabalalisa kahle kwezigaba ezinzima nezithambile ku-eutectic high-entropy alloys kungaholela ekuhlanganiseni okungcono kakhulu kwamandla kanye ne-ductility35,38,42,43.
Uhlelo lwe-CoCrFeNi luyingxubevange yesigaba esisodwa se-FCC efundwa kabanzi. Lolu hlelo lubonisa izakhiwo eziqinisa umsebenzi osheshayo44 kanye ne-ductility enhle kakhulu45,46 kokubili emazingeni okushisa aphansi naphezulu. Imizamo eyahlukene yenziwe yokuthuthukisa amandla ayo aphansi uma kuqhathaniswa (~300 MPa)47,48 okuhlanganisa ukucolisiswa okusanhlamvu25, i-heterogeneous microstructure49, precipitation50,51,52 kanye ne-plasticity-induced plasticity (TRIP)53. Ukucolisiswa okusanhlamvu kwe-cubic HEA CoCrFeNi egxile kubuso obusanhlamvu ngokudweba okubandayo ngaphansi kwezimo ezinzima kukhulisa amandla ukusuka cishe ku-300 MPa47.48 kuya ku-1.2 GPa25, kodwa kunciphisa ukulahlekelwa kwe-ductility kusuka ngaphezu kuka-60% kuya ku-12.6%. Ukwengezwa kwe-Al ku-HEA ye-CoCrFeNi kuholele ekwakhekeni kwesakhiwo se-microstructure esihlukile, esikhulise amandla esivuno saso safika ku-786 MPa kanye nobude bayo obuhlobene bufinyelela cishe ku-22%49. I-CoCrFeNi HEA yengezwe ne-Ti kanye ne-Al ukuze yakhe imvula, ngaleyo ndlela yakhe ukuqina kwemvula, ikhulise amandla ayo okukhiqiza abe ngu-645 MPa kanye nokuphakama kube ngu-39%51. Indlela ye-TRIP (i-cubic egxile ebusweni → ukuguqulwa kwe-hexahedral martensitic) kanye ne-twinning kwenyusa amandla aqinile we-CoCrFeNi HEA kuya ku-841 MPa kanye nobude ngesikhathi sekhefu kwaba ngu-76%53.
Kuphinde kwenziwa imizamo yokwengeza i-ceramic reinforcement ku-HEA face centered cubic matrix ukuze kuthuthukiswe izinhlanganisela eziphezulu ze-entropy ezingabonisa inhlanganisela engcono yamandla kanye ne-ductility. Izinhlanganisela ezine-entropy ephezulu zicutshungulwe yi-vacuum arc melting44, i-alloying mechanical45,46,47,48,52,53, i-spark plasma sintering46,51,52, i-vacuum hot pressing45, i-hot isostatic pressing47,48 kanye nokuthuthukiswa kwezinqubo zokukhiqiza ezingeziwe43. 50. Ama-Carbides, ama-oxides nama-nitrides afana ne-WC44, 45, 46, Al2O347, SiC48, TiC43, 49, TiN50 kanye ne-Y2O351 asetshenziswe njengokuqinisa nge-ceramic ekuthuthukisweni kwezinhlanganisela ze-HEA. Ukukhetha i-matrix ye-HEA efanele kanye ne-ceramic kubaluleke kakhulu uma uklama futhi uthuthukisa inhlanganisela ye-HEA eqinile nehlala isikhathi eside. Kulo msebenzi, i-CoCrFeNi ikhethwe njenge-matrix material. Amanani ahlukahlukene e-SiC engezwe ku-CoCrFeNi HEA futhi umphumela wawo ku-microstructure, ukwakheka kwesigaba, kanye nezakhiwo zemishini kwafundwa.
Izinsimbi ezihlanzekile kakhulu i-Co, i-Cr, i-Fe, ne-Ni (99.95 wt %) kanye ne-SiC powder (ukuhlanzeka okungu-99%, usayizi -400 mesh) ngendlela yezinhlayiya eziyisisekelo zasetshenziswa njengezinto zokusetshenziswa ekudalweni kwezinhlanganisela ze-HEA. Ukwakhiwa kwe-isoatomic ye-CoCrFeNi HEA kwaqala ukufakwa kusikhunta sethusi esipholile emanzini esine-hemispherical, bese ikamelo likhishwe ku-3 · 10-5 mbar. Igesi ye-argon ehlanzekile kakhulu yethulwa ukuze kuzuzwe i-vacuum edingekayo ekuncibilikeni kwe-arc ngama-electrode e-tungsten angasebenziseki. Ama-ingots avelayo aguquliwe futhi ancibilikisiwe izikhathi ezinhlanu ukuze kuqinisekiswe ukufana okuhle. Izinhlanganisela eziphezulu ze-entropy zezingoma ezihlukahlukene zalungiselelwa ngokwengeza inani elithile le-SiC kuzinkinobho eziwumphumela ze-equiatomic CoCrFeNi, eziphinde zenziwa i-homogension ngokuguquguquka okuphindwe kahlanu nokuncibilika esimweni ngasinye. Inkinobho ebunjiwe evela ekwakhiweni okuwumphumela yasikwa kusetshenziswa i-EDM ukuze kuqhutshekwe nokuhlolwa nokuhlukaniswa kwezinhlamvu. Amasampula ocwaningo lwe-microstructural alungiswa ngokwezindlela ezijwayelekile ze-metallographic. Okokuqala, amasampula ahlolwe kusetshenziswa isibonakhulu esikhanyayo (i-Leica Microscope DM6M) ngesofthiwe ye-Leica Image Analysis (Isazi Sesigaba se-LAS) sokuhlaziywa kwesigaba sobuningi. Izithombe ezintathu ezithathwe ezindaweni ezihlukene ezinengqikithi yendawo engaba ngu-27,000 µm2 zikhethelwe ukuhlaziywa kwesigaba. Olunye ucwaningo oluningiliziwe lwe-microstructural, olufaka ukuhlaziya ukwakheka kwamakhemikhali nokuhlaziywa kokusabalalisa izakhi, lwenziwa kusibonakhulu se-electron yokuskena (JEOL JSM-6490LA) efakwe uhlelo lokuhlaziya i-energy dispersive spectroscopy (EDS). Ukubonakala kwesakhiwo sekristalu senhlanganisela ye-HEA kwenziwa kusetshenziswa i-X-ray diffraction system (i-Bruker D2 phase shifter) kusetshenziswa umthombo we-CuKα onosayizi wesinyathelo esingu-0.04 °. Umthelela wezinguquko ze-microstructural ezimpahleni zomshini zezinhlanganisela ze-HEA wacwaningwa kusetshenziswa izivivinyo ze-Vickers microhardness nezivivinyo zokuminyanisa. Ukuze kuhlolwe ubulukhuni, kufakwa umthwalo ongu-500 N kumasekhondi ayi-15 kusetshenziswa okungenani ama-indent ayi-10 ngesifanekiso ngasinye. Ukuhlolwa kokucindezelwa kwezinhlanganisela ze-HEA ezingeni lokushisa kwegumbi kwenziwa kuma-specimens angama-rectangular (7 mm × 3 mm × 3 mm) emshinini wokuhlola umhlaba wonke we-Shimadzu 50KN (UTM) ngesilinganiso sokuqala sobunzima esingu-0.001/s.
Izinhlanganisela eziphezulu ze-entropy, kamuva ezibizwa ngokuthi amasampuli S-1 kuya ku-S-6, zalungiswa ngokwengeza u-3%, 6%, 9%, 12%, 15%, no-17% SiC (konke ngesisindo%) ku-matrix ye-CoCrFeNi . ngokulandelana. Isampula yereferensi engazange yengezwe i-SiC ngemuva kwalokhu ibizwa ngokuthi isampula S-0. Ama-micrographs optical wezinhlanganisela ze-HEA ezithuthukisiwe aboniswa ku-Fig. 1, lapho, ngenxa yokwengezwa kwezithasiselo ezihlukahlukene, i-microstructure yesigaba esisodwa se-CoCrFeNi HEA yaguqulwa yaba i-microstructure ehlanganisa izigaba eziningi ezine-morphology ehlukene, ubukhulu, nokusabalalisa. Inani le-SiC ekwakhekeni. Inani lesigaba ngasinye lanqunywa ekuhlaziyweni kwesithombe kusetshenziswa isofthiwe ye-LAS Phase Expert. Isethi yomfanekiso 1 (phezulu kwesokudla) ibonisa indawo eyisibonelo yalokhu kuhlaziya, kanye nengxenye yendawo yengxenye ngayinye yesigaba.
Ama-micrographs okubonayo wezinhlanganisela eziphezulu ze-entropy ezithuthukisiwe: (a) C-1, (b) C-2, (c) C-3, (d) C-4, (e) C-5 kanye (f) C- 6. Isingeniso sibonisa isibonelo semiphumela yokuhlaziywa kwesigaba sesithombe esisekelwe ngokungafani kusetshenziswa isofthiwe ye-LAS Phase Expert.
Njengoba kuboniswe emkhiwaneni. I-1a, i-eutectic microstructure eyakhiwe phakathi kwevolumu ye-matrix yenhlanganisela ye-C-1, lapho inani lezigaba ze-matrix ne-eutectic lilinganiselwa ku-87.9 ± 0.47% kanye no-12.1% ± 0.51%, ngokulandelana. Ku-composite (C-2) eboniswe ku-Fig. 1b, azikho izimpawu zokusabela kwe-eutectic ngesikhathi sokuqina, futhi i-microstructure ehluke ngokuphelele kuleyo ye-C-1 eyinhlanganisela iyabonwa. I-microstructure yenhlanganisela ye-C-2 ilungile uma kuqhathaniswa futhi iqukethe amapuleti amancane (ama-carbides) asatshalaliswa ngokufanayo esigabeni se-matrix (fcc). Izingxenye zevolumu ze-matrix ne-carbide zilinganiselwa ku-72 ± 1.69% kanye ne-28 ± 1.69%, ngokulandelana. Ngaphezu kwe-matrix kanye ne-carbide, isigaba esisha (i-silicide) sitholwe ku-C-3 composite, njengoba kuboniswe ku-Fig. 0.41%, 25.9 ± 0.53, kanye 47.6 ± 0.34, ngokulandelana. Esinye isigaba esisha (i-graphite) siphinde sabonwa ku-microstructure ye-C-4 composite; kwahlonzwa izigaba ezine sezizonke. Isigaba se-graphite sinomumo we-globular ohlukile onokugqama okumnyama ezithombeni ezibonakalayo futhi sitholakala kuphela ngamanani amancane (ingxenye yevolumu elinganiselwe icishe ibe ngu-0.6 ± 0.30%). Ku-composites C-5 kanye ne-C-6, izigaba ezintathu kuphela ezihlonziwe, futhi isigaba se-graphite esimnyama esihlukile kulezi zinhlanganisela sibonakala ngendlela yama-flakes. Uma kuqhathaniswa nama-graphite flakes ku-Composite S-5, ama-graphite flakes ku-Composite S-6 abanzi, mafushane, futhi avamile. Ukwanda okuhambisanayo kokuqukethwe kwegraphite kuphinde kwabonwa kusukela ku-14.9 ± 0.85% kunhlanganisela ye-C-5 kuya cishe ku-17.4 ± 0.55% kunhlanganisela ye-C-6.
Ukuze kuqhutshekwe kuphenywe nge-microstructure enemininingwane kanye nokwakheka kwamakhemikhali kwesigaba ngasinye kusihlanganisi se-HEA, amasampula ahlolwa kusetshenziswa i-SEM, nokuhlaziywa kwamaphuzu e-EMF kanye nokwenza imephu yamakhemikhali nakho kwenziwa. Imiphumela yenhlanganisela ye-C-1 ikhonjiswe kumfanekiso. 2, lapho ubukhona bezingxube ze-eutectic ezihlukanisa izifunda zesigaba esikhulu se-matrix bubonakala ngokucacile. Imephu yamakhemikhali ye-C-1 eyinhlanganisela iboniswa ku-Fig. 2c, lapho kungabonakala khona ukuthi i-Co, Fe, Ni, ne-Si zisatshalaliswa ngokufanayo esigabeni se-matrix. Kodwa-ke, inani elincane le-Cr litholakale esigabeni se-matrix uma kuqhathaniswa nezinye izakhi ze-HEA eyisisekelo, okuphakamisa ukuthi i-Cr yahlakazeka ngaphandle kwe-matrix. Ukwakheka kwesigaba esimhlophe se-eutectic esithombeni se-SEM kucebile nge-chromium nekhabhoni, okubonisa ukuthi i-chromium carbide. Ukungabi bikho kwezinhlayiya ze-SiC ezihlukene kusakhiwo se-microstructure, kuhlanganiswe nokuqukethwe okuphansi okubonwayo kwe-chromium ku-matrix kanye nokuba khona kwezingxube ze-eutectic eziqukethe izigaba ezicebile nge-chromium, kukhombisa ukubola okuphelele kwe-SiC ngesikhathi sokuncibilika. Njengomphumela wokubola kwe-SiC, i-silicon incibilika esigabeni se-matrix, futhi ikhabhoni yamahhala ixhumana ne-chromium ukuze yakhe i-chromium carbides. Njengoba kungabonwa, i-carbon kuphela eyanqunywa ngendlela ye-EMF, futhi ukwakheka kwesigaba kwaqinisekiswa ukuhlonza iziqongo ze-carbide eziphawulekayo kumaphethini we-X-ray diffraction.
(a) Isithombe se-SEM sesampula S-1, (b) isithombe esinwetshiwe, (c) isici semephu, (d) imiphumela ye-EMF ezindaweni ezibonisiwe.
Ukuhlaziywa kwenhlanganisela ye-C-2 kuboniswe kumfanekiso. 3. Ngokufana nokubukeka kwe-microscope ye-optical, ukuhlolwa kwe-SEM kwembula isakhiwo esihle esakhiwe izigaba ezimbili kuphela, nokuba khona kwesigaba esincane se-lamellar esatshalaliswa ngokulinganayo kulo lonke isakhiwo. isigaba se-matrix, futhi asikho isigaba se-eutectic. Ukusatshalaliswa kwe-elementi nokuhlaziywa kwephuzu le-EMF kwesigaba se-lamellar kwembule okuqukethwe okuphezulu kakhulu kwe-Cr (ophuzi) no-C (okuluhlaza) kulesi sigaba, okuphinda kukhombisa ukubola kwe-SiC ngesikhathi sokuncibilika kanye nokusebenzisana kwekhabhoni ekhishwe nomthelela we-chromium. . I-VEA matrix yenza isigaba se-lamellar carbide. Ukusatshalaliswa kwezakhi nokuhlaziywa kwamaphuzu kwesigaba se-matrix kubonise ukuthi iningi le-cobalt, insimbi, i-nickel ne-silicon likhona esigabeni se-matrix.
(a) Isithombe se-SEM sesampula S-2, (b) isithombe esinwetshiwe, (c) isici semephu, (d) imiphumela ye-EMF ezindaweni ezibonisiwe.
Izifundo ze-SEM zezinhlanganisela ze-C-3 zembula ukuba khona kwezigaba ezintsha ngaphezu kwezigaba ze-carbide ne-matrix. Imephu eyisisekelo (Fig. 4c) kanye nokuhlaziywa kwephuzu le-EMF (Fig. 4d) kubonisa ukuthi isigaba esisha sicebile ku-nickel, i-cobalt, ne-silicon.
(a) Isithombe se-SEM sesampula S-3, (b) isithombe esinwetshiwe, (c) isici semephu, (d) imiphumela ye-EMF ezindaweni ezibonisiwe.
Imiphumela yokuhlaziywa kwe-SEM ne-EMF yenhlanganisela ye-C-4 iboniswa ku-Fig. 5. Ngaphezu kwezigaba ezintathu ezibonwe ku-composite C-3, ukutholakala kwama-nodules e-graphite nakho kwatholakala. Ingxenye yevolumu yesigaba esicebile nge-silicon nayo iphakeme kunaleyo yenhlanganisela ye-C-3.
(a) Isithombe se-SEM sesampula S-4, (b) isithombe esinwetshiwe, (c) isici semephu, (d) imiphumela ye-EMF ezindaweni ezibonisiwe.
Imiphumela ye-spectra ye-SEM ne-EMF yezinhlanganisela S-5 kanye ne-S-6 iboniswa kuMfanekiso 1 no-2. 6 no-7, ngokulandelanayo. Ngaphezu kwenani elincane lama-sphere, ukuba khona kwama-graphite flakes nakho kwabonwa. Kokubili inani lama-graphite flakes kanye nengxenye yevolumu yesigaba esiqukethe i-silicon ekuhlanganiseni kwe-C-6 kukhulu kunenhlanganisela ye-C-5.
(a) Isithombe se-SEM sesampula C-5, (b) ukubuka okukhulisiwe, (c) imephu eyisisekelo, (d) imiphumela ye-EMF ezindaweni ezibonisiwe.
(a) Isithombe se-SEM sesampula S-6, (b) isithombe esinwetshiwe, (c) isici semephu, (d) imiphumela ye-EMF ezindaweni ezibonisiwe.
Ukulinganiswa kwesakhiwo se-Crystal kwezinhlanganisela ze-HEA nakho kwenziwa kusetshenziswa izilinganiso ze-XRD. Umphumela uboniswa kuMfanekiso 8. Kuphethini ye-diffraction yesisekelo se-WEA (S-0), kuphela iziqongo ezihambisana nesigaba se-fcc ezibonakalayo. Amaphethini okuphazamiseka kwe-X-ray wezinhlanganisela C-1, C-2, kanye ne-C-3 aveze ukuba khona kweziqongo ezengeziwe ezihambisana ne-chromium carbide (Cr7C3), futhi ukuqina kwazo kwakuphansi kumasampula C-3 kanye ne-C-4, abonisa lokho kanye ne-EMF yedatha yalawa masampuli. Iziqongo ezihambisana ne-Co/Ni silicides zaqashelwa kumasampuli S-3 kanye ne-S-4, futhi zihambisana nemiphumela yemephu ye-EDS eboniswe kuMfanekiso 2 no-3. Njengoba kuboniswe kuMfanekiso 3 nakuMfanekiso 4. 5 kanye neziqongo ze-S-6 zabonwa. elihambisana ne-graphite.
Kokubili izici ze-microstructural kanye ne-crystallographic zezinhlanganisela ezithuthukisiwe zibonise ukubola kwe-SiC eyengeziwe. Lokhu kungenxa yokuba khona kwe-chromium ku-matrix ye-VEA. I-Chromium inokuhlobana okunamandla kakhulu kwe-carbon 54.55 futhi ihlangana nekhabhoni yamahhala ukuze yakhe ama-carbides, njengoba kuboniswa ukwehla okuphawulwe kokuqukethwe kwe-chromium ku-matrix. U-Si udlulela esigabeni se-fcc ngenxa yokuhlakazeka kwe-SiC56. Ngakho-ke, ukwanda kokwengezwa kwe-SiC ku-HEA eyisisekelo kwaholela ekwandeni kwenani lesigaba se-carbide kanye nenani le-Si mahhala ku-microstructure. Kutholwe ukuthi le Si eyengeziwe ifakwe ku-matrix ekugxilweni okuphansi (ku-composites S-1 ne-S-2), kuyilapho ekugxilweni okuphezulu (inhlanganisela ye-S-3 kuya ku-S-6) iphumela ekufakweni okwengeziwe kwe-cobalt /. i-nickel silicide. I-enthalpy evamile yokwakheka kwe-Co kanye ne-Ni silicides, etholwe ngokuhlanganisa okuqondile kwe-calorimetry ephezulu yokushisa, ingu -37.9 ± 2.0, -49.3 ± 1.3, -34.9 ± 1.1 kJ mol -1 ye-Co2Si, i-CoSi ne-CoSi2, ngokulandelana, kuyilapho lezi amanani - 50.6 ± 1.7 kanye - 45.1 ± 1.4 kJ mol-157 ye-Ni2Si ne-Ni5Si2, ngokulandelanayo. Lawa manani aphansi kunokushisa kokwakheka kwe-SiC, okubonisa ukuthi ukuhlukaniswa kwe-SiC okuholela ekwakhekeni kwe-Co/Ni silicides kulungele ngamandla. Kuzo zombili izinhlanganisela ze-S-5 kanye ne-S-6, i-silicon yamahhala eyengeziwe yayikhona, eyamuncwa ngaphezu kokwakhiwa kwe-silicide. Le silicon yamahhala itholwe ifaka isandla ku-graphitization ebonwe kuma-steels ajwayelekile58.
Izakhiwo zemishini yezinhlanganisela ezithuthukisiwe eziqiniswe nge-ceramic ezisuselwe ku-HEA ziphenywa ngokuhlolwa kokucindezela kanye nokuhlolwa kokuqina. Amajika okucindezela kokucindezeleka kwezinhlanganisela ezithuthukisiwe aboniswa ku-Fig. 9a, nakuFig. 9b ikhombisa i-scatterplot phakathi kwamandla athile esivuno, amandla esivuno, ubulukhuni, kanye nokwelulwa kwezinhlanganisela ezithuthukisiwe.
(a) Amajika acindezelayo kanye (b) nama-scatterplots abonisa ingcindezi ethile yesivuno, amandla esivuno, ubulukhuni nobude. Qaphela ukuthi kuboniswa kuphela izifanekiso ze-S-0 kuye ku-S-4, njengoba izifanekiso ze-S-5 ne-S-6 ziqukethe ukonakala okukhulu kokulingisa.
Njengoba kubonakala emkhiwaneni. 9, amandla okukhiqiza akhuphuke esuka ku-136 MPa yesisekelo se-VES (C-0) kuya ku-2522 MPa yenhlanganisela ye-C-4. Uma kuqhathaniswa ne-WPP eyisisekelo, inhlanganisela ye-S-2 ibonise ukuphakama okuhle kakhulu ekuhlulekeni okungaba ngu-37%, futhi ibonise amanani aphezulu kakhulu wamandla esivuno (1200 MPa). Inhlanganisela enhle kakhulu yamandla kanye ne-ductility yale nhlanganisela kungenxa yokuthuthukiswa kwe-microstructure jikelele, kuhlanganise nokusabalalisa okufanayo kwe-carbide lamellae enhle kuyo yonke i-microstructure, okulindeleke ukuthi ivimbele ukunyakaza kokukhipha. Amandla esivuno senhlanganisela ye-C-3 ne-C-4 yi-1925 MPa kanye ne-2522 MPa, ngokulandelanayo. Lawa mandla esivuno esiphezulu angachazwa ngengxenye yevolumu ephezulu yezigaba ze-carbide zikasimende kanye ne-silicide. Kodwa-ke, ukuba khona kwalezi zigaba nakho kuholele ekwandiseni ngesikhathi sekhefu ngo-7% kuphela. Amajika e-stress-strain of the base composite CoCrFeNi HEA (S-0) kanye ne-S-1 ayi-convex, ekhombisa ukwenziwa kusebenze komthelela we-twinning noma i-TRIP59,60. Uma kuqhathaniswa nesampula ye-S-1, ijika le-stress-strain lesampula S-2 linomumo we-concave ochungechungeni olungaba ngu-10.20%, okusho ukuthi isiliphu esivamile sokugudluka siyindlela eyinhloko yokuguquguquka yesampula kulesi simo esikhubazekile60,61 . Kodwa-ke, izinga lokuqina kulesi sifanekiso lihlala liphezulu phezu kobubanzi obukhulu, futhi ezinkingeni eziphakeme ukushintshela ku-convexity nakho kuyabonakala (nakuba kungenakukhishwa ngaphandle kokuthi lokhu kungenxa yokwehluleka kwemithwalo ecindezelayo egcotshiwe). ). Ama-Composites C-3 kanye ne-C-4 ane-plasticity elinganiselwe kuphela ngenxa yokuba khona kwezingxenyana zevolumu ephezulu ye-carbides nama-silicides ku-microstructure. Ukuhlolwa kokucindezelwa kwamasampuli enhlanganisela C-5 kanye ne-C-6 akwenziwanga ngenxa yokukhubazeka okuphawulekayo kokusakazwa kulawa masampula wezinhlanganisela (bona u-Fig. 10).
Ama-stereomicrographs wokulimala kokusakazwa (akhonjiswa ngemicibisholo ebomvu) kumasampuli enhlanganisela C-5 kanye ne-C-6.
Imiphumela yokulinganisa ubulukhuni bezinhlanganisela ze-VEA ikhonjisiwe ku-Fig. 9b. Isisekelo se-WEA sinobulukhuni be-130±5 HV, futhi amasampula S-1, S-2, S-3 kanye ne-S-4 anamanani obunzima obungu-250±10 HV, 275±10 HV, 570±20 HV kanye 755±20 HV. Ukwanda kokuqina kwakuvumelana kahle noshintsho lwamandla esivuno atholwe ekuhlolweni kokucindezelwa futhi kwakuhlotshaniswa nokwanda kwenani lezinto eziqinile kunhlanganisela. Amandla esivuno esibaliwe asekelwe ekwakhekeni okuqondiwe kwesampula ngayinye nawo aboniswa kufig. 9b. Ngokuvamile, inhlanganisela engcono kakhulu yamandla esivuno (1200 MPa), ubulukhuni (275 ± 10 HV), kanye nokwelulwa okuhlobene nokwehluleka (~37%) kuqashelwa ku-C-2 eyinhlanganisela.
Ukuqhathaniswa kwamandla esivuno kanye nokwelulwa okuhlobene kwenhlanganisela ethuthukisiwe nezinto ezisetshenziswayo zamakilasi ahlukene kuboniswe ku-Fig. 11a. Izinhlanganisela ezisuselwe ku-CoCrFeNi kulolu cwaningo zibonise ukuphakama okuphezulu kunoma yiliphi izinga elinikeziwe lokucindezeleka62. Kungabonakala futhi ukuthi izakhiwo zezinhlanganisela ze-HEA ezithuthukiswe kulolu cwaningo zisendaweni ebingahlali muntu ngaphambilini yesiqephu samandla esivuno uma kuqhathaniswa nobude. Ngaphezu kwalokho, izinhlanganisela ezithuthukisiwe zinezinhlobonhlobo eziningi zamandla (277 MPa, 1200 MPa, 1925 MPa kanye 2522 MPa) kanye nokwelula (> 60%, 37%, 7.3% no-6.19%). Amandla esivuno nawo ayisici esibalulekile ekukhethweni kwezinto zokusebenza zezinhlelo zokusebenza zobunjiniyela ezithuthukile63,64. Mayelana nalokhu, izinhlanganisela ze-HEA zokusungulwa kwamanje zibonisa inhlanganisela enhle kakhulu yamandla esivuno kanye nobude. Lokhu kungenxa yokuthi ukungezwa kokuminyana okuphansi kwe-SiC kubangela izinhlanganisela ezinamandla aphezulu athile esivuno. Amandla athile esivuno kanye nokwelulwa kwezinhlanganisela ze-HEA kububanzi obufanayo ne-HEA FCC kanye ne-HEA ephikisayo, njengoba kuboniswe ku-Fig. 11b. Ukuqina namandla okuvunwa kwezinhlanganisela ezithuthukisiwe akubanga elifanayo nezingilazi ezinkulu zensimbi65 (Fig. 11c). Izingilazi ezinkulu zensimbi (BMS) zibonakala ngobulukhuni obuphezulu namandla akhiqizayo, kodwa ubude bazo bunomkhawulo wama-66,67. Kodwa-ke, ubulukhuni namandla okukhiqiza kwezinye zezinhlanganisela ze-HEA ezithuthukiswe kulolu cwaningo nakho kubonise ukunwetshwa okubalulekile. Ngakho-ke, kwaphethwa ngokuthi izinhlanganisela ezithuthukiswe yi-VEA zinenhlanganisela eyingqayizivele nefunwayo yezakhiwo zemishini zokusetshenziswa kwesakhiwo okuhlukahlukene. Le nhlanganisela eyingqayizivele yezakhiwo zemishini ingachazwa ngokuhlakazeka okufanayo kwama-carbides aqinile okwakhiwa ku-situ ku-matrix ye-FCC HEA. Kodwa-ke, njengengxenye yomgomo wokufeza inhlanganisela engcono yamandla, izinguquko ze-microstructural ezibangelwa ukwengezwa kwezigaba ze-ceramic kumele zicutshungulwe ngokucophelela futhi zilawulwe ukuze kugwenywe ukukhubazeka kokuphonsa, njengalezo ezitholakala kuzinhlanganisela ze-S-5 kanye ne-S-6, futhi i-ductility. ubulili.
Imiphumela yalolu cwaningo iqhathaniswe nezinto ezihlukahlukene zesakhiwo kanye nama-HEA: (a) ubude ngokumelene namandla esivuno62, (b) ukucindezeleka kwesivuno esithile ngokumelene ne-ductility63 kanye (c) nokukhiqiza amandla ngokumelene nobunzima65.
I-microstructure kanye nezakhiwo zemishini zochungechunge lwezinhlanganisela ze-HEA-ceramic ezisekelwe ohlelweni lwe-HEA CoCrFeNi ngokungezwa kwe-SiC zihlolisisiwe futhi iziphetho ezilandelayo zenziwe:
Izinhlanganisela eziphezulu ze-entropy alloy zingathuthukiswa ngempumelelo ngokungeza i-SiC ku-CoCrFeNi HEA kusetshenziswa indlela yokuncibilika kwe-arc.
I-SiC ibola ngesikhathi sokuncibilika kwe-arc, okuholela ekwakhekeni kwe-situ yezigaba ze-carbide, i-silicide ne-graphite, ubukhona kanye nengxenye yevolumu encike enanini le-SiC elingezwe ku-HEA eyisisekelo.
Izinhlanganisela ze-HEA zibonisa izakhiwo eziningi ezinhle kakhulu zemishini, ezinezakhiwo eziwela ezindaweni ebezingahlali muntu kumandla esivuno uma kuqhathaniswa nesakhiwo sokwelula. Amandla esivuno senhlanganisela ye-HEA eyenziwe kusetshenziswa i-6 wt% SiC yayingaphezu kokuphindwe kasishiyagalombili kwe-HEA eyisisekelo kuyilapho igcina i-ductility engu-37%.
Ukuqina namandla okukhiqiza ezinhlanganisela ze-HEA akububanzi bezingilazi zensimbi eziyinqwaba (BMG).
Okutholakele kusikisela ukuthi izinhlanganisela zengxubevange ephezulu ye-entropy zimelela indlela ethembisayo yokufeza inhlanganisela enhle kakhulu yezakhiwo zensimbi zomshini wokusetshenziswa kwesakhiwo esithuthukisiwe.
Isikhathi sokuthumela: Jul-12-2023