CoCrFeNi ndi ophunziridwa bwino nkhope-centered kiyubiki (fcc) mkulu-entropy aloyi (HEA) ndi ductility kwambiri koma mphamvu zochepa.Cholinga cha phunziroli ndikuwongolera mphamvu ndi ductility za HEA zoterezi powonjezera ma SiC osiyanasiyana pogwiritsa ntchito njira yosungunuka ya arc.Zatsimikiziridwa kuti kukhalapo kwa chromium m'munsi mwa HEA kumayambitsa kuwonongeka kwa SiC panthawi yosungunuka.Choncho, kuyanjana kwa carbon yaulere ndi chromium kumapangitsa kuti pakhale mapangidwe a chromium carbides, pamene silicon yaulere imakhalabe yankho muzitsulo za HEA ndi / kapena zimagwirizana ndi zinthu zomwe zimapanga maziko a HEA kupanga ma silicides.Pamene zinthu za SiC zikuwonjezeka, gawo la microstructure limasintha motsatira zotsatirazi: fcc → fcc + eutectic → fcc + chromium carbide flakes → fcc + chromium carbide flakes + silicide → fcc + chromium carbide flakes + silicide + graphite mipira / graphite flakes.Zomwe zimapangidwira zimawonetsa zinthu zambiri zamakina (mphamvu zokolola kuyambira 277 MPa pa 60% elongation mpaka 2522 MPa pa 6% elongation) poyerekeza ndi ma alloys ochiritsira ndi ma aloyi apamwamba a entropy.Zina mwazophatikiza zazikulu za entropy zomwe zidapangidwa zikuwonetsa kuphatikiza kwabwino kwamakina (kutulutsa mphamvu 1200 MPa, elongation 37%) ndikukhala madera omwe sanapezekepo pachithunzi chokulitsa kupsinjika kwa zokolola.Kuphatikiza pa kutalika kochititsa chidwi, kuuma ndi mphamvu zokolola zamagulu a HEA ndi ofanana ndi magalasi azitsulo ambiri.Chifukwa chake, akukhulupirira kuti kupanga mapangidwe apamwamba a entropy kumatha kuthandizira kuphatikizika kwazinthu zamakina pamakina apamwamba kwambiri.
Kukula kwa aloyi apamwamba a entropy ndi lingaliro latsopano lodalirika mu metallurgy1,2.High entropy alloys (HEA) awonetsa muzochitika zingapo kuphatikiza kwakukulu kwa thupi ndi makina, kuphatikiza kukhazikika kwamafuta3,4 superplastic elongation5,6 kutopa kukana7,8 kukana dzimbiri9,10,11, kukana kovala bwino12,13,14 ,15 ndi tribological properties15 ,16,17 ngakhale pa kutentha kwambiri18,19,20,21,22 ndi katundu makina pa kutentha otsika23,24,25.Kuphatikizika kwabwino kwamakina mu HEA nthawi zambiri kumabwera chifukwa cha zotsatira zinayi zazikuluzikulu, zomwe ndi mawonekedwe apamwamba a entropy26, kupotoza kolimba kwa lattice27, kufalikira kwapang'onopang'ono28 ndi cocktail effect29.Ma HEA nthawi zambiri amagawidwa ngati mitundu ya FCC, BCC ndi HCP.FCC HEA nthawi zambiri imakhala ndi zinthu zosinthira monga Co, Cr, Fe, Ni ndi Mn ndipo imawonetsa ductility kwambiri (ngakhale kutentha kotsika25) koma kutsika kwamphamvu.BCC HEA nthawi zambiri imakhala ndi zinthu zolimba kwambiri monga W, Mo, Nb, Ta, Ti ndi V ndipo zimakhala ndi mphamvu zambiri koma zimakhala zochepa komanso mphamvu zochepa kwambiri30.
Kusintha kwa microstructural kwa HEA kutengera makina, makina opangira thermomechanical ndi kuwonjezera zinthu zafufuzidwa kuti apeze kuphatikiza kwabwino kwa makina.CoCrFeMnNi FCC HEA imakhudzidwa ndi kupindika kwakukulu kwa pulasitiki ndi kugwedezeka kwakukulu, zomwe zimabweretsa kuwonjezeka kwakukulu kwa kuuma (520 HV) ndi mphamvu (1950 MPa), koma kukula kwa nanocrystalline microstructure (~ 50 nm) kumapangitsa alloy brittle31 .Zapezeka kuti kuphatikizika kwa twinning ductility (TWIP) ndi kusintha kwa pulasitiki (TRIP) mu CoCrFeMnNi HEAs kumapereka kuuma kwa ntchito komwe kumapangitsa kuti pakhale kulimba kwamphamvu, ngakhale kuwononga mphamvu zenizeni zamphamvu.Pansipa (1124 MPa) 32. Mapangidwe a microstructure wosanjikiza (wokhala ndi wosanjikiza woonda wopunduka komanso wosasinthika pachimake) mu CoCrFeMnNi HEA pogwiritsa ntchito kuwombera kunayambitsa kuwonjezeka kwa mphamvu, koma kusintha kumeneku kunali kochepa pafupifupi 700 MPa33.Pofufuza zipangizo zokhala ndi mphamvu zowonjezereka komanso zowonongeka, chitukuko cha multiphase HEAs ndi eutectic HEAs pogwiritsa ntchito zowonjezera za zinthu zopanda isoatomic zafufuzidwanso34,35,36,37,38,39,40,41.Zoonadi, zapezeka kuti kugawa bwino kwa magawo olimba ndi ofewa mu eutectic high-entropy alloys kungayambitse kuphatikizika kwabwinoko kwa mphamvu ndi ductility35,38,42,43.
Dongosolo la CoCrFeNi ndi gawo limodzi lophunziridwa kwambiri la FCC high-entropy alloy.Dongosololi likuwonetsa zinthu zowumitsa ntchito mwachangu44 komanso ductility45,46 yabwino kwambiri pakutentha komanso kutentha kwambiri.Kuyesera kosiyanasiyana kwapangidwa kuti apititse patsogolo mphamvu zake zochepa (~ 300 MPa) 47,48 kuphatikizapo kukonzanso tirigu25, heterogeneous microstructure49, precipitation50,51,52 ndi pulasitiki yopangidwa ndi kusintha (TRIP)53.Kukongoletsedwa kwa ma kyubiki amtundu wa HEA CoCrFeNi kozizira kwambiri kumawonjezera mphamvu kuchokera pa 300 MPa47.48 mpaka 1.2 GPa25, koma kumachepetsa kutayika kwa ductility kuchokera ku 60% mpaka 12.6%.Kuphatikiza kwa Al ku HEA ya CoCrFeNi kudapangitsa kuti pakhale mawonekedwe osasinthika, omwe adakulitsa mphamvu zake zokolola mpaka 786 MPa komanso kutalika kwake pafupifupi 22% 49.CoCrFeNi HEA idawonjezedwa ndi Ti ndi Al kuti ipange madzi, potero kupanga kulimbitsa mvula, kukulitsa mphamvu zake zokolola mpaka 645 MPa ndikutalikira mpaka 39% 51.Makina a TRIP (mawonekedwe a nkhope-centered kiyubiki → hexahedral martensitic transformation) ndi mapasa adakulitsa mphamvu yolimba ya CoCrFeNi HEA mpaka 841 MPa ndikutalikitsa panthawi yopuma mpaka 76% 53.
Kuyesera kwapangidwanso kuti awonjezere kulimbitsa kwa ceramic ku HEA face centered cubic matrix kuti apange ma entropy composites omwe amatha kuwonetsa kuphatikiza kwamphamvu ndi ductility.Ma composite okhala ndi entropy yayikulu adasinthidwa ndi vacuum arc melting44, makina alloying45,46,47,48,52,53, spark plasma sintering46,51,52, vacuum hot pressing45, kutentha kwa isostatic press47,48 ndi chitukuko cha njira zowonjezera,43. 50.Carbides, oxides ndi nitrides monga WC44, 45, 46, Al2O347, SiC48, TiC43, 49, TiN50 ndi Y2O351 akhala akugwiritsidwa ntchito ngati kulimbikitsanso ceramic popanga zida za HEA.Kusankha matrix olondola a HEA ndi ceramic ndikofunikira kwambiri popanga ndikupanga gulu lamphamvu komanso lolimba la HEA.Mu ntchitoyi, CoCrFeNi idasankhidwa ngati matrix.Zosiyanasiyana za SiC zinawonjezeredwa ku CoCrFeNi HEA ndipo zotsatira zake pa microstructure, mawonekedwe a gawo, ndi makina amakina anaphunziridwa.
Zitsulo zoyera kwambiri Co, Cr, Fe, ndi Ni (99.95 wt %) ndi ufa wa SiC (chiyero 99%, kukula -400 mesh) mu mawonekedwe a particles oyambira adagwiritsidwa ntchito ngati zida zopangira zida za HEA.Kuphatikizika kwa isoatomic kwa CoCrFeNi HEA kunayikidwa koyamba mu nkhungu yamkuwa yoziziritsidwa ndi madzi, ndiyeno chipindacho chinasamutsidwa kupita ku 3 · 10-5 mbar.Mpweya woyeretsedwa kwambiri wa argon umayambitsidwa kuti akwaniritse vacuum yofunikira kuti arc asungunuke ndi ma elekitirodi a tungsten osagwiritsidwa ntchito.Zomwe zimapangidwira zimatembenuzidwa ndikusinthidwa kasanu kuti zitsimikizire kuti zimakhala bwino.Zophatikiza zapamwamba za entropy zamitundu yosiyanasiyana zidakonzedwa ndikuwonjezera kuchuluka kwa SiC ku mabatani a equiatomic a CoCrFeNi, omwe adasinthidwanso ndi kutembenuzidwa kasanu ndikubwezeretsanso pazochitika zilizonse.Bokosi lopangidwa kuchokera kumagulu opangidwawo linadulidwa pogwiritsa ntchito EDM kuti muyesedwe ndi kuzindikiritsa.Zitsanzo za maphunziro a microstructural zidakonzedwa molingana ndi njira zodziwika bwino za metallographic.Choyamba, zitsanzozo zinayesedwa pogwiritsa ntchito microscope yowala (Leica Microscope DM6M) ndi mapulogalamu a Leica Image Analysis (LAS Phase Expert) kuti afufuze kuchuluka kwa gawo.Zithunzi zitatu zojambulidwa m'malo osiyanasiyana okhala ndi pafupifupi 27,000 µm2 zidasankhidwa kuti ziwunikidwe.Kafukufuku winanso watsatanetsatane wa microstructural, kuphatikiza kusanthula kwa kapangidwe ka mankhwala ndi kusanthula kagawidwe kazinthu, adachitika pa makina oonera ma electron microscope (JEOL JSM-6490LA) okhala ndi njira yowunikira mphamvu ya dispersive spectroscopy (EDS).Mawonekedwe a mawonekedwe a kristalo a gulu la HEA adagwiritsidwa ntchito pogwiritsa ntchito X-ray diffraction system (Bruker D2 phase shifter) pogwiritsa ntchito gwero la CuKα ndi kukula kwa sitepe ya 0.04 °.Zotsatira za kusintha kwa microstructural pamakina a HEA composites adaphunziridwa pogwiritsa ntchito mayeso a Vickers microhardness ndi mayeso oponderezedwa.Poyesa kuuma, katundu wa 500 N amayikidwa kwa 15 s pogwiritsa ntchito osachepera 10 indentations pa chitsanzo.Mayesero oponderezedwa a ma composites a HEA pa kutentha kwa firiji anachitidwa pa zitsanzo zamakona anayi (7 mm × 3 mm × 3 mm) pa Shimadzu 50KN universal test machine (UTM) pa mlingo woyamba wa 0.001 / s.
Zophatikiza zapamwamba za entropy, zomwe zimatchedwanso zitsanzo za S-1 mpaka S-6, zidakonzedwa powonjezera 3%, 6%, 9%, 12%, 15%, ndi 17% SiC (zonse ndi kulemera kwake%) ku masanjidwe a CoCrFeNi. .motsatana.Zitsanzo zomwe sizinawonjezedwe SiC zimatchedwanso chitsanzo cha S-0.Ma micrographs owoneka bwino azinthu zopangidwa ndi HEA akuwonetsedwa muzithunzi.1, kumene, chifukwa cha kuwonjezereka kwa zowonjezera zosiyanasiyana, gawo limodzi la microstructure la CoCrFeNi HEA linasinthidwa kukhala microstructure yomwe ili ndi magawo ambiri omwe ali ndi morphology, kukula kwake, ndi kugawa.Kuchuluka kwa SiC mu kapangidwe.Kuchuluka kwa gawo lirilonse kunatsimikiziridwa kuchokera ku kusanthula zithunzi pogwiritsa ntchito pulogalamu ya LAS Phase Expert.Chithunzi cha 1 (chapamwamba kumanja) chikuwonetsa gawo lachitsanzo la kusanthula uku, komanso gawo la gawo la gawo lililonse.
Kuwala kwa ma micrograph a magulu opangidwa apamwamba a entropy: (a) C-1, (b) C-2, (c) C-3, (d) C-4, (e) C-5 ndi (f) C- 6.Cholembacho chikuwonetsa chitsanzo cha zotsatira za kusanthula kwa gawo lazithunzi pogwiritsa ntchito pulogalamu ya LAS Phase Expert.
Monga momwe tawonetsera mkuyu.1a, eutectic microstructure yomwe inapangidwa pakati pa matrix a matrix a C-1, pomwe kuchuluka kwa matrix ndi magawo a eutectic akuti ndi 87.9 ± 0.47% ndi 12.1% ± 0.51%, motsatana.Muzophatikizika (C-2) zomwe zikuwonetsedwa mu Mkuyu 1b, palibe zizindikiro za eutectic reaction panthawi yolimba, ndipo microstructure yosiyana kwambiri ndi ya C-1 composite ikuwonetsedwa.Ma microstructure a C-2 composite ndi abwino kwambiri ndipo amakhala ndi mbale zoonda (carbides) zomwe zimagawidwa mofanana mu gawo la matrix (fcc).Magawo a matrix ndi carbide amawerengedwa kuti ndi 72 ± 1.69% ndi 28 ± 1.69%, motsatana.Kuwonjezera pa matrix ndi carbide, gawo latsopano (silicide) linapezedwa mu gulu la C-3, monga momwe tawonetsera mu Chithunzi 1c, pamene zigawo zamagulu a silicide, carbide, ndi matrix zimayesedwa pafupifupi 26.5% ± 0.41%, 25.9 ± 0.53, ndi 47.6 ± 0.34, motero.Gawo lina latsopano (graphite) linawonedwanso mu microstructure ya C-4 composite;magawo anayi onse adadziwika.Gawo la graphite liri ndi mawonekedwe a globular osiyana ndi kusiyana kwakuda muzithunzi zowoneka bwino ndipo amapezeka pang'ono chabe (gawo loyerekeza la voliyumu ndi pafupifupi 0.6 ± 0.30%).M'magulu a C-5 ndi C-6, magawo atatu okha ndi omwe adadziwika, ndipo gawo lamdima losiyana la graphite m'maguluwa limawoneka ngati mawonekedwe a flakes.Poyerekeza ndi ma graphite flakes mu Composite S-5, ma graphite flakes mu Composite S-6 ndi otambalala, afupi, komanso okhazikika.Kuwonjezeka kofananira kwa ma graphite kunawonedwanso kuchokera ku 14.9 ± 0.85% mu gulu la C-5 mpaka pafupifupi 17.4 ± 0.55% mu gulu la C-6.
Kuti mupitirize kufufuza mwatsatanetsatane za microstructure ndi mankhwala a gawo lirilonse mu gulu la HEA, zitsanzo zinayesedwa pogwiritsa ntchito SEM, ndi kusanthula mfundo za EMF ndi kupanga mapu a mankhwala kunachitikanso.Zotsatira za kompositi C-1 zikuwonetsedwa mkuyu.2, pomwe kukhalapo kwa zosakaniza za eutectic zolekanitsa madera a gawo lalikulu la matrix kumawoneka bwino.Mapu amankhwala a gulu la C-1 akuwonetsedwa mu Mkuyu 2c, pomwe zitha kuwoneka kuti Co, Fe, Ni, ndi Si zimagawidwa mofanana mu gawo la matrix.Komabe, kachulukidwe kakang'ono ka Cr kanapezeka mu gawo la matrix poyerekeza ndi zinthu zina za maziko a HEA, kutanthauza kuti Cr idatuluka mu matrix.Mapangidwe a gawo loyera la eutectic mu chithunzi cha SEM ali ndi chromium ndi carbon, kusonyeza kuti ndi chromium carbide.Kusapezeka kwa tinthu tating'ono ta SiC mu microstructure, kuphatikizidwa ndi kutsika kwa chromium mu masanjidwewo ndi kukhalapo kwa zosakaniza za eutectic zomwe zili ndi magawo olemera a chromium, zikuwonetsa kuwonongeka kwathunthu kwa SiC pakusungunuka.Chifukwa cha kuwonongeka kwa SiC, silicon imasungunuka mu gawo la matrix, ndipo mpweya waulere umalumikizana ndi chromium kupanga chromium carbides.Monga tikuonera, yekha carbon anali qualitatively anatsimikiza ndi EMF njira, ndipo gawo mapangidwe anatsimikiziridwa ndi chizindikiritso cha khalidwe carbide nsonga mu X-ray diffraction mapatani.
(a) Chithunzi cha SEM cha chitsanzo cha S-1, (b) chithunzi chokulitsidwa, (c) mapu a zinthu, (d) zotsatira za EMF pamalo osonyezedwa.
Kusanthula kwa kompositi C-2 kukuwonetsedwa mkuyu.3. Mofanana ndi maonekedwe a ma microscopy optical, kufufuza kwa SEM kunavumbulutsa kamangidwe kabwino kamene kamakhala ndi magawo awiri okha, ndi kukhalapo kwa gawo lochepa la lamellar lomwe limagawidwa mofanana mu dongosolo lonse.gawo la matrix, ndipo palibe gawo la eutectic.Kugawa kwazinthu ndi kusanthula kwa mfundo za EMF za gawo la lamellar kunavumbulutsa zambiri za Cr (chikasu) ndi C (zobiriwira) mu gawoli, zomwe zikuwonetsanso kuwonongeka kwa SiC pakusungunuka komanso kuyanjana kwa carbon yotulutsidwa ndi chromium effect. .Matrix a VEA amapanga gawo la lamellar carbide.Kugawidwa kwa zinthu ndi kusanthula mfundo za gawo la matrix kunawonetsa kuti ambiri mwa cobalt, chitsulo, nickel ndi silicon alipo mu gawo la matrix.
(a) Chithunzi cha SEM cha chitsanzo cha S-2, (b) chithunzi chokulitsidwa, (c) mapu a zinthu, (d) zotsatira za EMF pamalo osonyezedwa.
Kafukufuku wa SEM wamagulu a C-3 adawonetsa kukhalapo kwa magawo atsopano kuphatikiza magawo a carbide ndi matrix.Mapu oyambira (mkuyu 4c) ndi kusanthula mfundo za EMF (mkuyu 4d) zikuwonetsa kuti gawo latsopanoli lili ndi faifi tambala, cobalt, ndi silicon.
(a) Chithunzi cha SEM cha chitsanzo cha S-3, (b) chithunzi chokulitsidwa, (c) mapu a zinthu, (d) zotsatira za EMF pamalo osonyezedwa.
Zotsatira za kusanthula kwa SEM ndi EMF za gulu la C-4 zikuwonetsedwa muzithunzi.5. Kuphatikiza pa magawo atatu omwe amawonedwa mumagulu a C-3, kukhalapo kwa ma graphite nodule kunapezekanso.Gawo la voliyumu ya gawo lolemera la silicon ndilokweranso kuposa la C-3 composite.
(a) Chithunzi cha SEM cha chitsanzo cha S-4, (b) chithunzi chokulitsidwa, (c) mapu a zinthu, (d) zotsatira za EMF pamalo osonyezedwa.
Zotsatira za mawonekedwe a SEM ndi EMF a ma composite S-5 ndi S-6 akuwonetsedwa mu Zithunzi 1 ndi 2. 6 ndi 7, motsatira.Kuphatikiza pa magawo ochepa, kupezeka kwa ma graphite flakes kunawonedwanso.Onse chiwerengero cha graphite flakes ndi voliyumu gawo la silicon munali gawo mu gulu C-6 ndi zazikulu kuposa mu gulu C-5.
(a) Chithunzi cha SEM cha chitsanzo C-5, (b) mawonekedwe okulirapo, (c) mapu oyambira, (d) zotsatira za EMF pamalo osonyezedwa.
(a) Chithunzi cha SEM cha chitsanzo cha S-6, (b) chithunzi chokulirapo, (c) mapu a zinthu, (d) zotsatira za EMF pamalo osonyezedwa.
Mawonekedwe a kristalo a ma composites a HEA adachitidwanso pogwiritsa ntchito miyeso ya XRD.Chotsatira chikuwonetsedwa mu Chithunzi 8. Mu ndondomeko ya diffraction ya maziko a WEA (S-0), nsonga zokhazo zogwirizana ndi gawo la fcc zikuwonekera.Ma X-ray diffraction of composites C-1, C-2, ndi C-3 adawonetsa kukhalapo kwa nsonga zowonjezera zofananira ndi chromium carbide (Cr7C3), ndipo kulimba kwake kunali kotsika kwa zitsanzo C-3 ndi C-4, zomwe zikuwonetsa. zomwe zilinso ndi data ya EMF ya zitsanzo izi.Nsonga zofananira ndi ma silicides a Co / Ni zinawonedwa pa zitsanzo za S-3 ndi S-4, zomwe zimagwirizananso ndi zotsatira za mapu a EDS zomwe zikuwonetsedwa mu Zithunzi 2 ndi 3. Monga momwe tawonetsera mu Chithunzi 3 ndi Chithunzi 4. 5 ndi S-6 nsonga zinawoneka. zogwirizana ndi graphite.
Makhalidwe onse a microstructural ndi crystallographic of composites opangidwa amawonetsa kuwonongeka kwa SiC yowonjezera.Izi ndichifukwa cha kupezeka kwa chromium mu matrix a VEA.Chromium imakhala ndi mgwirizano wamphamvu kwambiri wa kaboni 54.55 ndipo imakumana ndi kaboni waulere kupanga ma carbides, monga zikuwonetsedwa ndi kuchepa kwa chromium mu matrix.Si imadutsa mugawo la fcc chifukwa cha kugawanika kwa SiC56.Choncho, kuwonjezeka kwa kuwonjezera kwa SiC ku maziko a HEA kunapangitsa kuti chiwerengero cha carbide chiwonjezeke komanso kuchuluka kwa Si kwaulere mu microstructure.Zapezeka kuti Si yowonjezerayi imayikidwa mu matrix pamagulu otsika (mumagulu a S-1 ndi S-2), pamene pamagulu apamwamba (zophatikizira S-3 mpaka S-6) zimapangitsa kuti pakhale cobalt yowonjezera /.nickel silicide.Enthalpy yokhazikika ya mapangidwe a Co ndi Ni silicides, omwe amapezedwa ndi kaphatikizidwe mwachindunji kutentha kwa calorimetry, ndi -37.9 ± 2.0, -49.3 ± 1.3, -34.9 ± 1.1 kJ mol -1 kwa Co2Si, CoSi ndi CoSi2, motsatira, pamene izi makhalidwe ndi - 50.6 ± 1.7 ndi - 45.1 ± 1.4 kJ mol-157 kwa Ni2Si ndi Ni5Si2, motero.Izi ndizotsika kuposa kutentha kwa SiC, zomwe zikuwonetsa kuti kupatukana kwa SiC komwe kumatsogolera ku mapangidwe a Co/Ni silicides ndikothandiza kwambiri.M'magulu onse a S-5 ndi S-6, silicon yowonjezera yaulere inalipo, yomwe idatengedwa kupyola kupangidwa kwa silicide.Silicon yaulere iyi yapezeka kuti ikuthandizira graphitization yomwe imawonedwa muzitsulo wamba58.
Zomwe zimapangidwira zamapangidwe opangidwa ndi ceramic-reinforced composites zochokera ku HEA zimafufuzidwa ndi mayeso oponderezedwa ndi kuyesa kuuma.Mapiritsi a kupsinjika-kupsinjika kwa ma composites opangidwa akuwonetsedwa m'ma Fig.9a, ndi mkuyu 9b ikuwonetsa kufalikira pakati pa mphamvu zokolola zenizeni, mphamvu zokolola, kuuma, ndi kufalikira kwa zopangapanga zotukuka.
(a) Mapiritsi oponderezedwa ndi (b) ma scatterplots omwe amawonetsa kupsinjika kwa zokolola, mphamvu zokolola, kuuma ndi kutalika.Dziwani kuti ndi zitsanzo zokha za S-0 mpaka S-4 zomwe zikuwonetsedwa, chifukwa zitsanzo za S-5 ndi S-6 zili ndi zolakwika zazikulu.
Monga tawonera mkuyu.9, mphamvu zokolola zawonjezeka kuchokera ku 136 MPa kwa maziko a VES (C-0) mpaka 2522 MPa ya C-4 composite.Poyerekeza ndi zofunika WPP, gulu S-2 anasonyeza elongation zabwino kwambiri kulephera pafupifupi 37%, komanso anasonyeza apamwamba kwambiri zokolola mphamvu makhalidwe (1200 MPa).Kuphatikizika kwabwino kwa mphamvu ndi ductility ya kompositi iyi ndi chifukwa cha kusintha kwa microstructure yonse, kuphatikizapo kugawa yunifolomu ya fine carbide lamellae mu microstructure yonse, yomwe ikuyembekezeka kuletsa kusuntha kwa dislocation.Mphamvu zokolola za C-3 ndi C-4 zophatikiza ndi 1925 MPa ndi 2522 MPa, motsatana.Mphamvu zokolola zazikuluzi zitha kufotokozedwa ndi gawo lalikulu la magawo a simenti ya carbide ndi silicide.Komabe, kupezeka kwa magawowa kudapangitsanso kuti pakhale kufalikira kwa 7%.Mipiringidzo ya kupsinjika kwa ma composites oyambira CoCrFeNi HEA (S-0) ndi S-1 ndi convex, kuwonetsa kuyambitsa kwa mapasa kapena TRIP59,60.Poyerekeza ndi chitsanzo S-1, kupsinjika-kupsyinjika kwachitsanzo S-2 kumakhala ndi mawonekedwe a concave pazovuta za 10.20%, zomwe zikutanthauza kuti kutsetsereka kwabwinoko ndiko njira yayikulu yopunduka yachitsanzo mu gawo lopundukali60,61 .Komabe, kuuma kwachitsanzochi kumakhalabe kwakukulu pamtundu waukulu wa zovuta, ndipo pazovuta kwambiri kusintha kwa convexity kumawonekeranso (ngakhale sizinganenedwe kuti izi zimachitika chifukwa cha kulephera kwa katundu wokakamiza wothira mafuta).).Ma Composites C-3 ndi C-4 ali ndi mapulasitiki ochepa okha chifukwa cha kukhalapo kwa tizigawo tambiri ta carbides ndi silicides mu microstructure.psinjika mayesero a zitsanzo za nsanganizo C-5 ndi C-6 sizinachitike chifukwa kwambiri kuponyera zolakwika pa zitsanzo za nsanganizo (onani mkuyu. 10).
Ma stereomicrographs a zolakwika zoponya (zowonetsedwa ndi mivi yofiyira) mu zitsanzo zamagulu C-5 ndi C-6.
Zotsatira zoyezera kuuma kwa ma composites a VEA zikuwonetsedwa mu Fig.9b ndi.Pansi WEA ili ndi kuuma kwa 130 ± 5 HV, ndipo zitsanzo za S-1, S-2, S-3 ndi S-4 zimakhala ndi kuuma kwa 250±10 HV, 275±10 HV, 570±20 HV ndi 755±20 HV.Kuwonjezeka kwa kuuma kunali kogwirizana bwino ndi kusintha kwa mphamvu zokolola zomwe zinapezedwa kuchokera ku mayesero oponderezedwa ndipo zimagwirizanitsidwa ndi kuwonjezeka kwa kuchuluka kwa zolimba mumagulu.The masamu yeniyeni zokolola mphamvu zochokera chandamale zikuchokera aliyense chitsanzo amasonyezedwanso mkuyu.9b ndi.Kawirikawiri, kuphatikiza kwabwino kwambiri kwa mphamvu zokolola (1200 MPa), kuuma (275 ± 10 HV), ndi kutalika kwachibale mpaka kulephera (~ 37%) kumawonedwa kwa gulu la C-2.
Kuyerekeza mphamvu zokolola ndi elongation wachibale wa kaphatikizidwe otukuka ndi zipangizo zosiyanasiyana makalasi akuwonetsedwa mkuyu 11a.Zophatikizika zochokera ku CoCrFeNi mu kafukufukuyu zidawonetsa kutalika kwakukulu pamlingo uliwonse wopsinjika62.Zitha kuwonekanso kuti katundu wamagulu a HEA opangidwa mu kafukufukuyu ali m'dera lomwe linali losagwiritsidwa ntchito kale la chiwembu cha mphamvu zokolola motsutsana ndi kutalika.Kuphatikiza apo, zopangira zomwe zidapangidwa zimakhala ndi mphamvu zambiri (277 MPa, 1200 MPa, 1925 MPa ndi 2522 MPa) ndi elongation (> 60%, 37%, 7.3% ndi 6.19%).Mphamvu zokolola ndizofunikiranso pakusankha zida zamaukadaulo apamwamba63,64.Pachifukwa ichi, zida za HEA zomwe zidapangidwa pano zikuwonetsa kuphatikiza kwamphamvu kwa zokolola komanso kutalika.Izi ndichifukwa choti kuwonjezera kwa SiC yotsika kwambiri kumabweretsa zophatikiza zokhala ndi mphamvu zokolola zambiri.Mphamvu yeniyeni ya zokolola ndi kutalika kwa zigawo za HEA zili mumtundu wofanana ndi HEA FCC ndi HEA refractory, monga momwe tawonetsera pa Chithunzi 11b.Kulimba ndi mphamvu zokolola zamagulu opangidwa ndizomwe zimakhala zofanana ndi magalasi akuluakulu azitsulo65 (mkuyu 11c).Magalasi akuluakulu azitsulo (BMS) amadziwika ndi kuuma kwakukulu komanso mphamvu zokolola, koma kutalika kwawo ndi kochepa 66,67.Komabe, kuuma ndi kutulutsa mphamvu zamagulu ena a HEA opangidwa mu kafukufukuyu adawonetsanso kutalika kwakukulu.Chifukwa chake, zidatsimikiziridwa kuti zophatikizika zopangidwa ndi VEA zimakhala ndi zida zapadera komanso zofunidwa zamakina pazogwiritsa ntchito zosiyanasiyana.Kuphatikizika kwapadera kumeneku kwamakina kumatha kufotokozedwa ndi kubalalitsidwa kofanana kwa ma carbides olimba omwe amapangidwa mu situ mu FCC HEA matrix.Komabe, monga gawo la cholinga chokwaniritsa kuphatikizika kwamphamvu kwamphamvu, kusintha kwapang'onopang'ono komwe kumabwera chifukwa chowonjezera magawo a ceramic kuyenera kuphunziridwa mosamala ndikuwongoleredwa kuti tipewe zolakwika zoponya, monga zomwe zimapezeka mumagulu a S-5 ndi S-6, ndi ductility.jenda.
Zotsatira za phunziroli zinafaniziridwa ndi zipangizo zosiyanasiyana zamapangidwe ndi HEAs: (a) elongation motsutsana ndi mphamvu zokolola62, (b) kupsinjika kwa zokolola zenizeni motsutsana ndi ductility63 ndi (c) kutulutsa mphamvu motsutsana ndi kuuma65.
Ma microstructure ndi makina amitundu yambiri ya HEA-ceramic composites yotengera HEA CoCrFeNi system ndi kuwonjezera kwa SiC aphunziridwa ndipo zotsatirazi zapangidwa:
Ma composites apamwamba a entropy alloy amatha kupangidwa bwino powonjezera SiC ku CoCrFeNi HEA pogwiritsa ntchito njira yosungunuka ya arc.
SiC imawonongeka panthawi ya kusungunuka kwa arc, zomwe zimapangitsa kuti pakhale magawo a carbide, silicide ndi graphite, kupezeka ndi gawo la voliyumu yomwe imadalira kuchuluka kwa SiC yowonjezeredwa ku HEA yoyambira.
Zophatikizira za HEA zimawonetsa zinthu zambiri zamakina, zokhala ndi zinthu zomwe zimagwera m'malo omwe simunagwirepo kale pamphamvu ya zokolola motsutsana ndi chiwembu cha elongation.Mphamvu zokolola za gulu la HEA lopangidwa pogwiritsa ntchito 6 wt% SiC inali yoposa kasanu ndi katatu kuposa ya HEA yoyambira pomwe ikusunga 37% ductility.
Kulimba ndi mphamvu zokolola zamagulu a HEA ali mumitundu yosiyanasiyana ya magalasi azitsulo (BMG).
Zomwe zapezazi zikuwonetsa kuti ma composites apamwamba a entropy alloy akuyimira njira yodalirika yokwaniritsira kuphatikiza kwazitsulo zamakina pamakina apamwamba kwambiri.
Nthawi yotumiza: Jul-12-2023