CoCrFeNi ƙwararren ƙwararriyar cubic (fcc) ce mai ƙarfi-entropy gami (HEA) wacce aka yi nazari sosai tare da ingantacciyar ductility amma iyakataccen ƙarfi.Mayar da hankali na wannan binciken shine inganta daidaituwar ƙarfi da ductility na irin waɗannan HEA ta hanyar ƙara nau'i daban-daban na SiC ta amfani da hanyar narkewa.An tabbatar da cewa kasancewar chromium a cikin tushe HEA yana haifar da bazuwar SiC yayin narkewa.Don haka, hulɗar carbon kyauta tare da chromium yana kaiwa zuwa ga samuwar chromium carbides, yayin da silicon kyauta ya kasance a cikin bayani a cikin tushe HEA da/ko yana hulɗa tare da abubuwan da suka zama tushen HEA don samar da silicides.Yayin da abun ciki na SiC ya karu, tsarin microstructure yana canzawa a cikin jeri mai zuwa: fcc → fcc + eutectic → fcc + chromium carbide flakes → fcc + chromium carbide flakes + silicide → fcc + chromium carbide flakes + silicide + graphite bukukuwa / flakes graphite.Abubuwan da aka samo asali suna nuna nau'in kayan aikin injiniya mai yawa (ƙararfin samar da wutar lantarki daga 277 MPa a kan 60% elongation zuwa 2522 MPa a 6% elongation) idan aka kwatanta da al'ada na al'ada da kuma manyan entropy alloys.Wasu daga cikin manyan abubuwan haɗin gwiwar entropy da aka haɓaka suna nuna kyakkyawan haɗin haɗin kayan aikin injiniya (ƙarfin samar da 1200 MPa, elongation 37%) kuma sun mamaye yankunan da ba a iya samun su a baya akan zane-zanen haɓakar damuwa-elongation.Baya ga tsayin daka na ban mamaki, tauri da ƙarfin samarwa na abubuwan haɗin HEA suna cikin kewayo ɗaya da manyan gilashin ƙarfe.Sabili da haka, an yi imanin cewa haɓakar haɓakar haɓakar haɓakar haɓakar haɓakar haɓakar haɓakar haɓakar haɓakar haɓakar haɓakar haɓakar haɓakar haɓakar haɓakar haɓakar haɓakar haɓakar haɓakar haɓakar haɓakar haɓakar haɓakar haɓakar haɓakar kayan aikin injiniya ce don aikace-aikacen tsarin ci gaba.
Haɓaka manyan allunan entropy shine sabon ra'ayi mai ban sha'awa a cikin ƙarfe1,2.High entropy Alloys (HEA) sun nuna a cikin lokuta da dama wani kyakkyawan haɗuwa da kayan aikin jiki da na inji, ciki har da babban kwanciyar hankali na thermal3,4 superplastic elongation5,6 juriya gajiya7,8 lalata juriya9,10,11, kyakkyawan juriya na lalacewa12,13,14 ,15 da tribological Properties15 ,16,17 ko da a high zafin jiki18,19,20,21,22 da inji Properties a low yanayin zafi23,24,25.Kyakkyawan hadewar kaddarorin inji a cikin HEA yawanci ana danganta su zuwa manyan tasirin guda huɗu, wato babban saitin entropy26, karkataccen lattice mai ƙarfi27, jinkirin watsawa28 da tasirin hadaddiyar giyar29.HEA yawanci ana rarraba su azaman FCC, BCC da nau'ikan HCP.FCC HEA yawanci ya ƙunshi abubuwan canzawa kamar Co, Cr, Fe, Ni da Mn kuma yana nuna kyakkyawan aiki (har ma a ƙananan zafin jiki25) amma ƙarancin ƙarfi.BCC HEA yawanci ya ƙunshi manyan abubuwa masu yawa kamar W, Mo, Nb, Ta, Ti da V kuma yana da ƙarfi sosai amma ƙarancin ductility da ƙarancin takamaiman ƙarfi30.
An bincika gyare-gyaren microstructural na HEA dangane da machining, sarrafa thermomechanical da ƙari na abubuwa don samun mafi kyawun haɗin kayan aikin injiniya.CoCrFeMnNi FCC HEA yana fuskantar mummunar nakasar filastik ta hanyar matsananciyar matsa lamba, wanda ke haifar da karuwa mai yawa a cikin taurin (520 HV) da ƙarfi (1950 MPa), amma haɓakar microstructure na nanocrystalline (~ 50 nm) ya sa gami da raguwa31. .An gano cewa haɗa nau'ikan tagwayen ductility (TWIP) da canza canjin filastik (TRIP) zuwa CoCrFeMnNi HEAs yana ba da ƙarfin aiki mai kyau wanda ke haifar da haɓakar ƙwanƙwasa mai ƙarfi, kodayake a kashe ainihin ƙimar ƙarfin ƙarfi.Da ke ƙasa (1124 MPa) 32. Samar da ƙananan ƙananan ƙwayoyin cuta (wanda ya ƙunshi ƙananan nakasassu na bakin ciki da maras kyau) a cikin CoCrFeMnNi HEA ta yin amfani da harbin harbi ya haifar da karuwa da ƙarfi, amma wannan haɓakawa ya iyakance ga kimanin 700 MPa33.A cikin neman kayan aiki tare da mafi kyawun haɗin ƙarfi da ductility, ci gaban HEAs multiphase da eutectic HEAs ta amfani da ƙari na abubuwan da ba na isoatomic an kuma bincika34,35,36,37,38,39,40,41.Lalle ne, an gano cewa mafi kyawun rarraba sassa masu wuya da taushi a cikin eutectic high-entropy alloys na iya haifar da ingantacciyar haɗuwa da ƙarfi da ductility35,38,42,43.
Tsarin CoCrFeNi shine babban binciken FCC mai girma-entropy alloy mataki-daya.Wannan tsarin yana nuna kayan aiki mai ƙarfi na gaggawa44 da kyakkyawan ductility45,46 a duka ƙananan zafi da zafi.An yi yunƙuri iri-iri don inganta ƙarancin ƙarfinsa (~ 300 MPa) 47,48 gami da gyaran hatsi25, microstructure daban-daban49, hazo50,51,52 da filastik da aka haifar da canji (TRIP)53.Gyaran hatsi na simintin gyaran fuska mai siffar cubic HEA CoCrFeNi ta zanen sanyi a ƙarƙashin yanayi mai tsanani yana ƙara ƙarfi daga kusan 300 MPa47.48 zuwa 1.2 GPa25, amma yana rage asarar ductility daga fiye da 60% zuwa 12.6%.Bugu da ƙari na Al zuwa HEA na CoCrFeNi ya haifar da samuwar ƙananan ƙwayoyin cuta, wanda ya ƙaru ƙarfin yawan amfanin sa zuwa 786 MPa da haɓakar dangi zuwa kusan 22%49.An ƙara CoCrFeNi HEA tare da Ti da Al don samar da hazo, ta haka ne ke haɓaka haɓakar hazo, ƙara ƙarfin yawan amfanin sa zuwa 645 MPa da haɓaka zuwa 39%51.Tsarin TRIP (fuskar mai siffar cubic → hexahedral martensitic transformation) da tagwaye sun ƙara ƙarfin jujjuyawar CoCrFeNi HEA zuwa 841 MPa da haɓakawa a karya zuwa 76%53.
An kuma yi ƙoƙari don ƙara ƙarfafa yumbura zuwa ga HEA fuska mai siffar cubic matrix don haɓaka manyan abubuwan haɗin gwiwar entropy waɗanda zasu iya nuna ingantaccen haɗin ƙarfi da ductility.Abubuwan da aka haɗa tare da babban entropy an sarrafa su ta hanyar injin arc narkewa44, alloying na injiniya45,46,47,48,52,53, spark plasma sintering46,51,52, vacuum hot pressing45, zafi isostatic pressing47,48 da kuma ci gaban ƙarin masana'antu tafiyar matakai43, 50.Carbides, oxides da nitrides kamar WC44, 45, 46, Al2O347, SiC48, TiC43, 49, TiN50 da Y2O351 an yi amfani da su azaman ƙarfafa yumbu a cikin haɓakar abubuwan haɗin HEA.Zaɓin matrix HEA daidai da yumbu yana da mahimmanci musamman lokacin zayyanawa da haɓaka ƙaƙƙarfan haɗin HEA mai dorewa.A cikin wannan aikin, an zaɓi CoCrFeNi azaman kayan matrix.An ƙara adadin SiC iri-iri zuwa CoCrFeNi HEA kuma an yi nazarin tasirin su akan ƙayyadaddun ƙayyadaddun lokaci, da kaddarorin inji.
High-tsarki karafa Co, Cr, Fe, da Ni (99.95 wt%) da SiC foda (tsarki 99%, girman -400 raga) a cikin nau'i na farko barbashi da aka yi amfani da albarkatun kasa don ƙirƙirar HEA composites.Abun da ke tattare da isoatomic na CoCrFeNi HEA an fara sanya shi a cikin kwandon jan ƙarfe mai sanyaya ruwa mai sanyaya ruwa, sannan aka fitar da ɗakin zuwa 3 · 10-5 mbar.An gabatar da iskar gas mai ƙarfi na argon don cimma matsayar da ake buƙata don narkewar baka tare da na'urorin lantarki na tungsten mara amfani.Abubuwan da aka samu suna jujjuya su kuma a narke su sau biyar don tabbatar da kyakkyawan kamanni.An shirya manyan abubuwan da suka haɗa da manyan abubuwan haɗin gwiwa ta hanyar ƙara wani adadin SiC zuwa maɓallan CoCrFeNi da aka samo asali, waɗanda aka sake daidaita su ta hanyar jujjuyawar sau biyar da sake narkewa a kowane hali.Maɓallin da aka ƙera daga abin da aka samo asali an yanke ta amfani da EDM don ƙarin gwaji da halayyar.An shirya samfurori don nazarin ƙananan ƙananan abubuwa bisa ga daidaitattun hanyoyin ƙarfe.Da farko, an yi nazarin samfuran ta amfani da na'ura mai ma'ana (Leica Microscope DM6M) tare da software na Leica Hotuna Analysis (LAS Phase Expert) don nazarin lokaci mai ƙididdigewa.Hotuna uku da aka ɗauka a wurare daban-daban tare da jimlar yanki na kusan 27,000 µm2 an zaɓi don nazarin lokaci.An gudanar da ƙarin cikakkun bayanai kan nazarin ƙananan ƙananan ƙwayoyin cuta, gami da nazarin abubuwan da ke tattare da sinadarai da nazarin rarraba kashi, akan na'urar duba microscope na lantarki (JEOL JSM-6490LA) sanye take da tsarin bincike na tarwatsa makamashi (EDS).An yi fasalin tsarin kristal na haɗin HEA ta amfani da tsarin diffraction na X-ray (Bruker D2 lokaci shifter) ta amfani da tushen CuKα tare da girman mataki na 0.04 °.An yi nazarin tasirin sauye-sauye na microstructural akan kayan aikin injiniya na abubuwan haɗin HEA ta amfani da gwaje-gwajen microhardness na Vickers da gwajin matsawa.Don gwajin taurin, ana amfani da nauyin 500 N don s 15 ta amfani da aƙalla 10 indentations kowane samfurin.An gudanar da gwaje-gwajen matsawa na abubuwan haɗin HEA a cikin zafin jiki a kan samfurori na rectangular (7 mm × 3 mm × 3 mm) akan na'urar gwaji ta duniya ta Shimadzu 50KN (UTM) a matakin farko na 0.001/s.
Manyan entropy composites, daga baya ake magana a kai a matsayin samfuran S-1 zuwa S-6, an shirya su ta ƙara 3%, 6%, 9%, 12%, 15%, da 17% SiC (duk ta nauyi%) zuwa matrix CoCrFeNi .bi da bi.Samfurin tunani wanda ba a ƙara SiC ba daga baya ana kiransa samfurin S-0.Ana nuna micrographs na gani na abubuwan haɗin gwiwar HEA da aka haɓaka a cikin ɓangarorin.1, inda, saboda ƙari na ƙari daban-daban, ƙananan microstructure guda ɗaya na CoCrFeNi HEA an canza shi zuwa ƙananan ƙwayoyin cuta wanda ya ƙunshi matakai da yawa tare da nau'i-nau'i daban-daban, girma, da rarrabawa.Adadin SiC a cikin abun da ke ciki.An ƙayyade adadin kowane lokaci daga nazarin hoto ta amfani da software na ƙwararrun lokaci na LAS.Ƙaddamarwa zuwa Hoto 1 (babban dama) yana nuna misalin yanki don wannan bincike, da kuma ɓangaren yanki na kowane ɓangaren lokaci.
Micrographs na gani na ɓullo da manyan entropy composites: (a) C-1, (b) C-2, (c) C-3, (d) C-4, (e) C-5 da (f) C- 6.Wurin shigar yana nuna misali na sakamakon binciken yanayin hoto na tushen bambanci ta amfani da software na ƙwararrun Mataki na LAS.
Kamar yadda aka nuna a cikin fig.1a, eutectic microstructure kafa tsakanin matrix kundin na C-1 composite, inda aka kiyasta adadin matrix da eutectic matakai a matsayin 87.9 ± 0.47% da 12.1% ± 0.51%, bi da bi.A cikin hadaddiyar giyar (C-2) da aka nuna a cikin siffa 1b, babu alamun eutectic amsawa a lokacin ƙarfafawa, kuma ana lura da microstructure gaba ɗaya daga na C-1 composite.Ƙirƙirar ƙirar C-2 tana da kyau sosai kuma ta ƙunshi faranti na bakin ciki (carbides) waɗanda aka rarraba iri ɗaya a cikin tsarin matrix (fcc).An kiyasta ƙananan juzu'in matrix da carbide a 72 ± 1.69% da 28 ± 1.69%, bi da bi.Bugu da ƙari ga matrix da carbide, an samo sabon lokaci (silicide) a cikin C-3 composite, kamar yadda aka nuna a cikin 1c. 0.41%, 25.9 ± 0.53, da 47.6 ± 0.34, bi da bi.An kuma lura da wani sabon lokaci (graphite) a cikin microstructure na C-4 composite;An gano jimlar matakai huɗu.Tsarin graphite yana da nau'i na musamman na duniya tare da bambanci mai duhu a cikin hotuna masu gani kuma yana samuwa a cikin ƙananan adadi (ƙididdigar girman juzu'i kusan 0.6 ± 0.30%).A cikin haɗe-haɗen C-5 da C-6, matakai uku ne kawai aka gano, kuma yanayin bambance-bambancen graphite mai duhu a cikin waɗannan abubuwan haɗin gwiwar yana bayyana a cikin nau'in flakes.Idan aka kwatanta da flakes ɗin graphite a cikin Composite S-5, faifan graphite a cikin Composite S-6 sun fi fadi, gajarta, kuma mafi na yau da kullun.An kuma lura da haɓaka daidai da abun ciki na graphite daga 14.9 ± 0.85% a cikin haɗin C-5 zuwa kusan 17.4 ± 0.55% a cikin haɗin C-6.
Don ci gaba da bincika cikakkun bayanai na microstructure da sinadarai na kowane lokaci a cikin haɗin gwiwar HEA, an bincika samfurori ta amfani da SEM, kuma an yi nazarin ma'anar EMF da taswirar sinadarai.Ana nuna sakamako don haɗakar C-1 a cikin fig.2, inda aka gani a fili gaban eutectic gaurayawan raba yankuna na babban matrix lokaci.An nuna taswirar sinadarai na C-1 a cikin siffa 2c, inda za a iya ganin Co, Fe, Ni, da Si an rarraba su daidai a cikin matrix lokaci.Koyaya, an sami ƙaramin adadin Cr a cikin matrix lokacin idan aka kwatanta da sauran abubuwan tushen HEA, yana ba da shawarar cewa Cr ya bazu daga cikin matrix.Abubuwan da ke tattare da farin eutectic lokaci a cikin hoton SEM yana da wadata a cikin chromium da carbon, yana nuna cewa chromium carbide ne.Rashin ɓangarorin SiC masu hankali a cikin microstructure, haɗe tare da ƙarancin abun ciki na chromium da aka lura a cikin matrix da kasancewar abubuwan haɗin eutectic waɗanda ke ɗauke da matakan chromium-arziƙi, yana nuna cikakkiyar bazuwar SiC yayin narkewa.Sakamakon rugujewar SiC, silicon yana narkewa a cikin matrix lokaci, kuma carbon kyauta yana hulɗa tare da chromium don samar da chromium carbides.Kamar yadda ake iya gani, kawai carbon ne kawai aka ƙaddara ta hanyar EMF, kuma an tabbatar da samuwar lokaci ta hanyar gano kololuwar carbide na halayen halayen X-ray diffraction.
(a) Hoton SEM na samfurin S-1, (b) girman hoto, (c) taswirar abubuwa, (d) sakamakon EMF a wuraren da aka nuna.
Ana nuna nazarin hadadden C-2 a cikin fig.3. Hakazalika da bayyanar a cikin ƙananan ƙwayoyin cuta, jarrabawar SEM ta nuna wani tsari mai kyau wanda ya ƙunshi nau'i biyu kawai, tare da kasancewar wani lokaci mai laushi mai laushi wanda aka rarraba a ko'ina cikin tsarin.matrix lokaci, kuma babu wani lokaci eutectic.Rarraba kashi da kuma nazarin maki na EMF na lokacin lamellar ya bayyana babban abun ciki na Cr (rawaya) da C (kore) a cikin wannan lokaci, wanda kuma yana nuna bazuwar SiC yayin narkewa da hulɗar carbon da aka saki tare da tasirin chromium. .Matrix na VEA yana samar da lokaci na carbide lamellar.Rarraba abubuwa da nazarin ma'ana na lokaci na matrix ya nuna cewa yawancin cobalt, baƙin ƙarfe, nickel da silicon suna cikin lokacin matrix.
(a) Hoton SEM na samfurin S-2, (b) girman hoto, (c) taswirar abubuwa, (d) sakamakon EMF a wuraren da aka nuna.
Nazarin SEM na abubuwan haɗin C-3 sun nuna kasancewar sabbin matakai ban da matakan carbide da matrix.Taswirar farko (Fig. 4c) da EMF maki bincike (Fig. 4d) sun nuna cewa sabon lokaci yana da wadata a nickel, cobalt, da silicon.
(a) Hoton SEM na samfurin S-3, (b) girman hoto, (c) taswirar abubuwa, (d) sakamakon EMF a wuraren da aka nuna.
Sakamakon binciken SEM da EMF na haɗin C-4 an nuna su a cikin Fig.5. Baya ga matakai uku da aka lura a cikin C-3 mai hade, an kuma sami kasancewar nodules na graphite.Har ila yau, juzu'in juzu'i na siliki-arzikin lokaci ya fi na C-3 composite.
(a) Hoton SEM na samfurin S-4, (b) girman hoto, (c) taswirar abubuwa, (d) sakamakon EMF a wuraren da aka nuna.
Sakamakon SEM da EMF na abubuwan da suka hada da S-5 da S-6 an nuna su a cikin Figures 1 da 2. 6 da 7, bi da bi.Bugu da ƙari, ƙananan ƙananan sassa, an kuma lura da kasancewar flakes na graphite.Dukansu adadin flakes na graphite da juzu'in juzu'i na siliki-dauke da lokaci a cikin rukunin C-6 sun fi girma fiye da haɗin C-5.
(a) Hoton SEM na samfurin C-5, (b) hangen nesa mai girma, (c) taswirar farko, (d) sakamakon EMF a wuraren da aka nuna.
(a) Hoton SEM na samfurin S-6, (b) girman hoto, (c) taswirar abubuwa, (d) sakamakon EMF a wuraren da aka nuna.
Hakanan an yi fasalin sifa na kristal na abubuwan haɗin HEA ta amfani da ma'aunin XRD.An nuna sakamakon a cikin Hoto 8. A cikin nau'i mai banƙyama na tushe WEA (S-0), kawai kololuwar da suka dace da lokacin fcc suna bayyane.X-ray diffraction alamu na composites C-1, C-2, da C-3 sun bayyana gaban ƙarin kololuwa daidai da chromium carbide (Cr7C3), da kuma ƙarfin su ya kasance ƙasa ga samfurori C-3 da C-4, wanda ya nuna. wanda kuma tare da bayanan EMF don waɗannan samfurori.An lura da kololuwar da suka dace da Co / Ni silicides don samfurori S-3 da S-4, sake daidaitawa tare da sakamakon taswirar EDS da aka nuna a cikin Figures 2 da 3. Kamar yadda aka nuna a cikin Hoto 3 da Hoto 4. 5 da S-6 kololuwa an lura. daidai da graphite.
Dukansu sifofin microstructural da crystallographic na abubuwan da aka haɓaka sun nuna bazuwar SiC da aka ƙara.Wannan ya faru ne saboda kasancewar chromium a cikin matrix VEA.Chromium yana da kusanci mai ƙarfi don carbon 54.55 kuma yana amsawa tare da carbon kyauta don samar da carbide, kamar yadda aka nuna ta raguwar abun ciki na chromium na matrix.Si ya shiga cikin fcc lokaci saboda rabuwar SiC56.Don haka, karuwa a cikin ƙarar SiC zuwa tushe HEA ya haifar da karuwa a cikin adadin lokaci na carbide da adadin Sisi kyauta a cikin microstructure.An gano cewa an ajiye wannan ƙarin Si a cikin matrix a ƙananan ƙananan (a cikin haɗin S-1 da S-2), yayin da mafi girma (composites S-3 zuwa S-6) yana haifar da ƙarin ƙaddamarwa na cobalt /.nickel siliki.Matsakaicin enthalpy na samuwar Co da Ni silicides, wanda aka samu ta hanyar haɗin kai tsaye mai ƙarfi calorimetry, shine -37.9 ± 2.0, -49.3 ± 1.3, -34.9 ± 1.1 kJ mol -1 don Co2Si, CoSi da CoSi2, bi da bi, yayin da waɗannan dabi'u sune - 50.6 ± 1.7 da - 45.1 ± 1.4 kJ mol-157 don Ni2Si da Ni5Si2, bi da bi.Waɗannan dabi'u sun yi ƙasa da zafi na samuwar SiC, yana nuna cewa rabuwar SiC da ke haifar da samuwar Co/Ni silicides yana da daɗi da kuzari.A cikin duka S-5 da S-6 composites, ƙarin siliki na kyauta ya kasance, wanda aka ɗauka fiye da samuwar siliki.An samo wannan siliki na kyauta don ba da gudummawa ga graphitization da aka lura a cikin ƙarfe na al'ada58.
Abubuwan da aka haɓaka na kayan aikin yumbu da aka haɓaka dangane da HEA ana bincikar su ta gwaje-gwajen matsawa da gwaje-gwajen taurin.An nuna maƙasudin matsananciyar damuwa na abubuwan da aka haɓaka a cikin figs.9a, kuma a cikin siffa 9b yana nuna raguwa tsakanin ƙayyadaddun ƙarfin yawan amfanin ƙasa, ƙarfin samar da ƙarfi, taurin, da haɓakar abubuwan da aka haɓaka.
(a) Matsakaicin matsa lamba da (b) ɓangarorin tarwatsawa suna nuna ƙayyadaddun damuwa na yawan amfanin ƙasa, ƙarfin yawan amfanin ƙasa, taurin kai da tsawo.Lura cewa samfurori S-0 zuwa S-4 ne kawai aka nuna, kamar yadda samfurori S-5 da S-6 suka ƙunshi manyan lahani.
Kamar yadda aka gani a cikin fig.9, ƙarfin yawan amfanin ƙasa ya karu daga 136 MPa don tushe VES (C-0) zuwa 2522 MPa don haɗin C-4.Idan aka kwatanta da ainihin WPP, da S-2 composite nuna mai kyau elongation zuwa kasawa na game da 37%, da kuma nuna muhimmanci mafi girma yawan amfanin ƙasa ƙarfi dabi'u (1200 MPa).Kyakkyawan haɗuwa da ƙarfi da ductility na wannan hadaddiyar giyar shine saboda haɓakawa a cikin ƙananan ƙananan ƙwayoyin cuta, ciki har da rarraba daidaitattun ƙwayoyin carbide lamellae a ko'ina cikin microstructure, wanda ake sa ran ya hana motsi motsi.Ƙarfin yawan amfanin ƙasa na C-3 da C-4 composites sune 1925 MPa da 2522 MPa, bi da bi.Ana iya bayyana waɗannan ƙarfin yawan amfanin ƙasa ta babban juzu'in juzu'in siminti da silicide.Koyaya, kasancewar waɗannan matakan kuma ya haifar da haɓakawa a lokacin hutu na kawai 7%.Matsakaicin matsananciyar damuwa na tushen abubuwan haɗin gwiwar CoCrFeNi HEA (S-0) da S-1 sune madaidaicin, yana nuna kunna tasirin tagwaye ko TRIP59,60.Idan aka kwatanta da samfurin S-1, ma'aunin damuwa-nauyin samfurin S-2 yana da nau'i mai ma'ana a wani nau'i na kusan 10.20%, wanda ke nufin cewa ƙaddamarwa ta al'ada ita ce babban yanayin nakasar samfurin a cikin wannan gurɓataccen yanayi60,61 .Koyaya, ƙimar hardening a cikin wannan samfurin ya kasance sama da babban kewayon iri, kuma a mafi girman nau'ikan ana iya canzawa zuwa juzu'i (ko da yake ba za a iya yanke hukunci ba cewa wannan yana faruwa ne saboda gazawar nauyin matsa lamba).).Abubuwan da aka haɗa C-3 da C-4 suna da ƙarancin filastik kawai saboda kasancewar mafi girman juzu'i na carbides da silicides a cikin ƙananan ƙwayoyin cuta.Ba a gudanar da gwaje-gwajen matsa lamba na samfuran abubuwan haɗin gwiwar C-5 da C-6 ba saboda manyan lahani na simintin gyare-gyare akan waɗannan samfuran abubuwan haɗin gwiwa (duba siffa 10).
Stereomicrographs na lahani na simintin gyare-gyare (wanda ke nuni da jajayen kibau) a cikin samfuran abubuwan haɗakar C-5 da C-6.
Ana nuna sakamakon auna taurin abubuwan haɗin VEA a cikin ɓangarorin.9b ku.WEA tushe yana da taurin 130 ± 5 HV, kuma samfuran S-1, S-2, S-3 da S-4 suna da ƙimar taurin 250 ± 10 HV, 275 ± 10 HV, 570 ± 20 HV da 755± 20 HV.Ƙarfafa taurin ya kasance cikin kyakkyawar yarjejeniya tare da canji a cikin ƙarfin da aka samu daga gwaje-gwajen matsawa kuma an haɗa shi da karuwa a cikin adadin daskararru a cikin hadaddiyar giyar.Ƙarfin ƙididdiga na ƙayyadaddun yawan amfanin ƙasa bisa maƙasudin abun da ke tattare da kowane samfurin kuma ana nuna shi a cikin fig.9b ku.Gabaɗaya, mafi kyawun haɗuwa da ƙarfin yawan amfanin ƙasa (1200 MPa), taurin (275 ± 10 HV), da haɓakar dangi zuwa gazawar (~ 37%) ana lura da hadadden C-2.
Kwatanta ƙarfin yawan amfanin ƙasa da haɓakar dangi na haɓakar haɓakawa tare da kayan nau'ikan nau'ikan nau'ikan an nuna su a cikin siffa 11a.Abubuwan da aka haɗa akan CoCrFeNi a cikin wannan binciken sun nuna haɓakar haɓakawa a kowane matakin damuwa62.Hakanan za'a iya ganin cewa kaddarorin abubuwan haɗin gwiwar HEA da aka haɓaka a cikin wannan binciken sun ta'allaka ne a cikin yankin da ba a taɓa amfani da shi a baya ba na makircin ƙarfin amfanin gona tare da haɓakawa.Bugu da ƙari, abubuwan da aka haɓaka suna da nau'i mai yawa na haɗin gwiwa (277 MPa, 1200 MPa, 1925 MPa da 2522 MPa) da kuma elongation (> 60%, 37%, 7.3% da 6.19%).Ƙarfin haɓakawa kuma muhimmin abu ne a cikin zaɓin kayan don aikace-aikacen injiniya na ci gaba63,64.Dangane da wannan, abubuwan haɗin HEA na abin da aka ƙirƙira na yanzu suna nuna kyakkyawar haɗuwa da ƙarfin yawan amfanin ƙasa da haɓakawa.Wannan saboda ƙari na ƙananan ƙarancin SiC yana haifar da haɗakarwa tare da ƙayyadaddun ƙarfin yawan amfanin ƙasa.Ƙarfin ƙayyadaddun ƙayyadaddun ƙayyadaddun ƙayyadaddun ƙima da haɓakar abubuwan haɗin gwiwar HEA suna cikin kewayon HEA FCC da HEA mai jujjuyawa, kamar yadda aka nuna a cikin siffa 11b.Ƙarfin ƙarfi da haɓakar abubuwan da aka haɓaka suna cikin kewayo ɗaya kamar na manyan gilashin ƙarfe na ƙarfe65 (Fig. 11c).Manyan gilashin ƙarfe (BMS) suna da ƙarfi da ƙarfi da ƙarfi, amma tsayin su yana da iyaka 66,67.Koyaya, ƙarfin ƙarfi da ƙarfin samar da wasu abubuwan haɗin gwiwar HEA waɗanda aka haɓaka a cikin wannan binciken kuma sun nuna tsayin daka.Don haka, an ƙarasa da cewa abubuwan haɗin da VEA suka haɓaka suna da na musamman da kuma neman-bayan haɗe-haɗe na kayan inji don aikace-aikacen tsarin daban-daban.Ana iya bayanin wannan haɗin keɓaɓɓen haɗin kayan aikin injiniya ta hanyar rarrabuwar kawuna na manyan carbides da aka kafa a wurin a cikin matrix FCC HEA.Duk da haka, a matsayin wani ɓangare na manufar samun ingantacciyar haɗin gwiwa mai ƙarfi, ƙananan canje-canjen da ke haifar da ƙarin matakan yumbura dole ne a yi nazari sosai da kuma sarrafa su don kauce wa lahani, kamar waɗanda aka samu a cikin S-5 da S-6 composites, da kuma ductility.jinsi.
An kwatanta sakamakon wannan binciken tare da kayan gini daban-daban da HEAs: (a) haɓakawa da ƙarfin amfanin ƙasa62, (b) ƙayyadaddun damuwa na yawan amfanin ƙasa da ductility63 da (c) ƙarfin samar da ƙarfi tare da taurin65.
An yi nazarin microstructure da kaddarorin injina na jerin abubuwan haɗin gwiwar HEA-ceramic dangane da tsarin HEA CoCrFeNi tare da ƙari na SiC kuma an yanke hukunci masu zuwa:
Za a iya samun nasarar haɓaka manyan abubuwan haɗin gwanon entropy ta ƙara SiC zuwa CoCrFeNi HEA ta amfani da hanyar narkewar baka.
SiC yana raguwa a lokacin narkewar baka, yana haifar da samuwar situtin carbide, silicide da graphite matakan, kasancewar da juzu'in ƙarar wanda ya dogara da adadin SiC da aka ƙara zuwa tushe HEA.
Haɗaɗɗen HEA suna nuna kyawawan kaddarorin injiniyoyi da yawa, tare da kaddarorin da suka faɗo cikin wuraren da ba a taɓa yin su ba a baya akan ƙarfin yawan amfanin ƙasa tare da ƙirar tsawo.Ƙarfin yawan amfanin ƙasa na HEA da aka yi ta amfani da 6 wt% SiC ya fi sau takwas fiye da na tushe HEA yayin da yake riƙe 37% ductility.
Ƙarfin da aka samu na abubuwan haɗin HEA suna cikin kewayon manyan gilashin ƙarfe (BMG).
Abubuwan da aka gano sun nuna cewa manyan abubuwan haɗin gwal na entropy suna wakiltar wata hanya mai ban sha'awa don cimma kyakkyawar haɗuwa da kayan aikin ƙarfe-kayan aiki don aikace-aikacen tsarin ci gaba.
Lokacin aikawa: Jul-12-2023