I-Metallurgy Ekuthuthukisweni Kwezinto Ezinesakhiwo Esincane
Ukuthuthukiswa kwesayensi yezinto zokwakha emashumini eminyaka amuva nje kubonise isiqondiso esicacile ngokwengeziwe: abantu badinga izinto zokwakha eziqinile, ezilula, ezingagqwali kakhulu, nezisebenza kahle kakhulu kwezinhlelo zokusebenza eziningi—kusukela kwezokuthutha kanye namandla kuya kumadivayisi kagesi kanye nokunakekelwa kwempilo. Phakathi kwalezi zidingo, izinto zokwakha ezakhiwe ngendlela entsha ziye zavela njengenye yezindlela ezithembisayo kakhulu. Lezi zinto zokwakha zinezici noma osayizi abahlukile esikalini se-nanometer (cishe u-1–100 nm), okuholela ezicini ezahlukene—ngokuvamile eziphakeme—zomshini, zikagesi, zokushisa, kanye nezamakhemikhali uma kuqhathaniswa nezinto ezivamile. Yilapho i-metallurgy idlala khona indima ebalulekile: hhayi nje njengesayensi yezinsimbi, kodwa njengesifundo esilawula indlela isakhiwo sangaphakathi sezinto zokwakha esakhiwa ngayo, esiguqulwa ngayo, futhi esilawulwa ngayo ukuze kufezwe ukusebenza okuthile.
Ukuqonda izinto ezakhiwe ngendlela encane kanye nesilinganiso sazo esiyingqayizivele
Izinto ezakhiwe ngendlela engalingani zingaba izinsimbi, ama-alloy, izinto zobumba, noma izinto ezihlanganisiwe ezinezinhlamvu zekristalu ezinhle kakhulu noma eziqukethe ama-nanoprecipitates, ama-nanolayer, ngisho nama-nanoscale pores. Kulolu sayizi, kuvela izenzakalo "ezintsha" ezahlukahlukene. Isibonelo, lapho usayizi wezinhlamvu zensimbi wehliswa esikalini se-nanometer, amandla ayanda ngenxa yenani elikhulayo lemingcele yezinhlamvu ezivimbela ukunyakaza kokuhlukana—indlela eyinhloko yokuguqulwa kwepulasitiki ezinsimbini. Lesi simo sivame ukuchazwa ngobudlelwano beHall-Petch, lapho amandla anda khona ngokuncipha kosayizi wezinhlamvu (nakuba ngobukhulu obuncane kakhulu kunezimo ezithile ezihlukile).
Ngaphezu kwamandla, izakhiwo ezincane nazo zingandisa ukumelana nokuguguleka, zithuthukise impendulo yokukhathala, zishintshe ukuhanjiswa kukagesi/kokushisa, futhi zithonye ukusabela kwendawo. Ngakho-ke, isihluthulelo sezinto ezakhiwe ezincane akusikho nje "okuncane," kodwa ukulawula: usayizi, ukusatshalaliswa, ukuma, kanye nokuqina kwezakhiwo ezincane kumele kulungiselelwe injongo.
I-Metallurgy "njengomakhi" wezakhiwo: kusukela ezinqubweni kuya ezimpahleni
I-metallurgy yesimanje ingabhekwa njengebhuloho phakathi kwenqubo-isakhiwo-izakhiwo-ukusebenza. Ngokwesimo sezakhiwo ezincane, i-metallurgy inesibopho sokunquma izinqubo zokukhiqiza kanye nokwelashwa okukwazi ukwakha izici ezincane njalo. Lokhu kuhlanganisa i-metallurgy ebonakalayo (ukuxoxa ngesakhiwo sekristalu, izigaba, ukuguqulwa), i-mechanical metallurgy (ukuguqulwa, ukuqina, ukwehluleka), kanye ne-process metallurgy (ukuncibilikisa, ukusakaza, ukuthungela, ukumboza, kanye namasu okukhiqiza athuthukile).
Ekuthuthukisweni kwezinto ezakhiwe ngendlela encane, izinselele ze-metallurgical ziyinkimbinkimbi kakhulu ngenxa yokuzwela okuphezulu kwezinto ezincane ekushiseni, izinga lokupholisa, ukusabalala kwe-athomu, kanye namandla angaphezulu. Izakhiwo ezincane zivame ukungazinzile ngokwe-thermodynamic; izinhlamvu ezincane zikhula kalula uma zivezwa ekushiseni, okudinga amasu "okuvala" izakhiwo ezincane ukuvimbela ukukhula okusheshayo kokusanhlamvu.
Amasu e-Metallurgical okwakha izakhiwo ezincane
1. Ukuguqulwa Okukhulu Kwepulasitiki (i-SPD)
Indlela eyodwa ebalulekile ekusetshenzisweni kwensimbi ukucwengisisa usayizi wezinhlamvu ngokusebenzisa ukuguqulwa okukhulu ngaphandle kokushintsha kakhulu ubukhulu bokugcina. Amasu athandwayo e-SPD afaka phakathi i-Equal Channel Angular Pressing (ECAP) kanye ne-High-Pressure Torsion (HPT). Lezi zinqubo ziphoqa insimbi ukuthi idlule ezinhlotsheni ezinkulu, yakha ama-sub-grains acwebezelayo, ekugcineni ifinyelele osayizi abancane kakhulu noma abancane.
Inzuzo ye-SPD ukuthi ingandisa kakhulu amandla ngaphandle kwesidingo sama-alloy ayinkimbinkimbi. Kodwa-ke, izinselele zifaka phakathi ukulawula ukulingana kwesakhiwo, ukulinganiselwa kosayizi womkhiqizo, kanye nokuqina kwesakhiwo esincane lapho izinto zisetshenziswa emazingeni okushisa aphezulu.
2. Ama-alloy akhiwe ngendlela encane ngokusebenzisa imvula kanye nokuqina kokuhlakazeka
I-Alloy metallurgy isebenzisa ama-precipitate—izinhlayiya zesigaba sesibili ezakhiwe ngesikhathi sokwelashwa kokushisa okuthile—ukwandisa amandla. Ku-nanoscale, ama-precipitate amahle kakhulu futhi asatshalaliswa ngokulinganayo angavimbela ngempumelelo ukunyakaza kokuhlukana. Izibonelo zifaka phakathi ama-aluminium alloy e-2xxx/7xxx noma ama-superalloy asekelwe ku-nickel, lapho izinga lokushisa nesikhathi sokuguga kungakhiqiza ama-nanoprecipitate anamandla kakhulu.
Enye indlela i-oxide dispersion strengthenized (ODS), esebenzisa izinhlayiya ze-nanometer oxide ezizinzile kakhulu ukuthuthukisa amandla kanye nokumelana nokuqhekeka emazingeni okushisa aphezulu. Izinto ze-ODS zibhekwa kabanzi njengezamandla kanye nezicelo zemvelo eziyingozi ngoba ama-nanodispersoids anciphisa ukunyakaza komngcele wokusanhlamvu futhi avimbela ukuguquka emazingeni okushisa aphezulu.
3. Ukusansimbi kwempuphu kanye nokuhlanganiswa kwemishini
Ukusansimbi kwempuphu kubalulekile ngoba kungakhiqiza izakhiwo ezincane kusukela ekuqaleni. Enye indlela ebalulekile ukuhlanganisa ngomshini, inqubo yokugaya enamandla aphezulu exuba kakhulu izimpuphu zensimbi, okubangela ukuguqulwa okuphindaphindiwe, ukushisela okubandayo, kanye nokuqhekeka kwezinhlayiya ukuze kwakhiwe izimpuphu ezinezakhiwo ezi-ultrafine noma ezingaphelele. Lezi zimpuphu zibe sezixutshwa noma zihlanganiswe (isb., ngokucindezela okushisayo, i-HIP, noma i-SPS) zibe izingxenye eziqinile.
Izinzuzo zayo zifaka phakathi ukuguquguquka kokwakheka (kufaka phakathi ama-alloy okunzima ukuwakha ngokuncibilikisa) kanye nekhono lokukhiqiza izakhiwo ezincane ezifanayo. Izinselele zifaka phakathi ukushiswa kwempuphu, ukungcola okuvela emishinini yokugaya, kanye nokulawulwa kokungena kwe-porosity ngesikhathi sokusila.
4. Ukwakheka kwe-nanostructure kanye nobunjiniyela bomphezulu
Izinhlelo eziningi zidinga ukusebenza okuphezulu kwendawo—njengokugqwala nokumelana nokuguguleka—ngaphandle kokushintsha ngokuphelele izinto. I-surface metallurgy inikeza amasu okumboza njenge-PVD/CVD, i-electrodeposition, i-thermal spray, kanye ne-modified nitriding kanye ne-carburizing. I-nanocrystalline coatings ingandisa ubulukhuni, inciphise i-coefficient of friction, futhi ithuthukise ukumelana ne-oxidation.
Ngaphezu kwalokho, ubunjiniyela bomphezulu buvumela i-gradient yesakhiwo: ungqimba lwangaphandle luqinile kakhulu (i-nanostructure), kuyilapho umongo uhlala uthambile. Le ndlela ibalulekile ezingxenyeni zemishini ezifana nama-shaft, amagiya, namathuluzi okusika.
Ukuchazwa kwezimpawu: ukuqinisekisa ukuthi izakhiwo ezincane zakhiwe ngempela
Ukuthuthukiswa kwezinto ezakhiwe ngendlela encane akukwazi ukuhlukaniswa nobuchwepheshe obuyinkimbinkimbi bokuchaza. I-Metallurgy isebenzisa:
– I-SEM/TEM ukuze kubonwe usayizi wezinhlamvu, ama-nanoprecipitates, kanye namaphutha ekristalu.
– I-XRD ukuhlonza izigaba, ukucindezeleka okusele, kanye nosayizi wekristalu.
– I-EBSD ukuze idwebe ukuqondiswa kwekristalu kanye nokusatshalaliswa kwemingcele yokusanhlamvu.
– I-APT (i-Atom Probe Tomography) ukuze kubonwe ukusatshalaliswa kwama-athomu kanye nokwehla kwezinga lama-athomu.
Ngaphandle kokuchazwa kwezimpawu, inqubo iba nje "ukuzama nokwenza amaphutha." Ngokuchazwa kwezimpawu, ubudlelwano benqubo-isakhiwo-nempahla bungahlelwa ngokwesayensi futhi buthuthukiswe.
Izinselele eziyinhloko: ukuzinza kokushisa kanye nobukhulu bezimboni
Nakuba izakhiwo ezincane zinikeza ukuthuthukiswa okukhulu kwezakhiwo, kuvela izinselele ezimbili ezinkulu. Okokuqala ukuzinza kwesakhiwo esincane. Osayizi abancane kakhulu bezinhlamvu banamandla aphezulu omngcele wokusanhlamvu; lapho izinto zishiswa, okusanhlamvu kuvame ukukhula, okunciphisa amandla. Ukuze kuxazululwe lokhu, i-metallurgy ithuthukise amasu afana nokwengeza izinto zokuhlanganisa ezivimbela ukufuduka komngcele wokusanhlamvu, ukwakheka kwama-precipitate "okunamathisela" imingcele yokusanhlamvu (i-Zener pinning), kanye nomklamo oqondile wemijikelezo yokwelashwa kokushisa.
Inselele yesibili ukukwazi ukukhulisa. Amasu amaningi okwakha izinto ezincane asebenza kahle kakhulu elabhorethri kodwa kunzima ukuwasebenzisa ekukhiqizeni ngobuningi ngenxa yezindleko, izinga lokukhiqiza, noma imikhawulo yosayizi. Ucwaningo lwamanje lugxile ekwenzeni inqubo ihambisane nokukhiqiza kwesimanje—kufaka phakathi ukuhlanganiswa nokukhiqiza okungeziwe (ukuphrinta kwe-3D yensimbi) okungakha izakhiwo ezincane kakhulu ngamanani aphezulu okupholisa, ezibe seziqiniswa ngokwelashwa kokushisa okwengeziwe.
Izicelo: kusukela kwezokuthutha kuya kumandla kanye ne-biomedicine
Izinto ezakhiwe ngendlela engalingani zinamandla okuguqula imikhakha eyahlukene. Ezimbonini zezimoto nezindiza, ama-alloy akhiwe ngendlela engalingani anganciphisa isisindo semoto ngaphandle kokubeka engcupheni amandla nokuphepha. Emkhakheni wamandla, izinto ze-ODS nezinye izakhiwo ezincane zibalulekile ekusetshenzisweni kwezinga lokushisa eliphezulu, ama-turbine, kanye nezingxenye ze-reactor. Kuma-elekthronikhi, izakhi ezincane kanye nezakhiwo ezincane kungathinta ukuhanjiswa kwegesi kanye nokuthembeka kokuxhumana. Ngisho nase-biomedicine, izindawo ezakhiwe ngendlela engalingani ezifakweni zingathuthukisa ukuhlanganiswa kwezicubu ngokulawula ubulukhuni kanye namandla omhlaba.
I-Penutup
I-Metallurgy ekuthuthukisweni kwezinto ezakhiwe ngendlela encane iyisibonelo esiyinhloko sendlela isayensi yakudala eguquka ngayo ibe ubuchwepheshe besikhathi esizayo. Ngokulawula ukuhlanganiswa, ukuguqulwa, ukwelashwa kokushisa, i-powder metallurgy, kanye nezinqubo zobunjiniyela bomphezulu, ochwepheshe be-metallurg bayakwazi "ukwakha" izakhiwo zangaphakathi kuze kufike ku-nanoscale, badale izinto ezinokusebenza okungafinyeleleki ngaphambili. Izinselele zokuzinza kanye nokukhiqizwa kwenqwaba zisekhona, kodwa isiqondiso sentuthuko sicacile: izinto ezakhiwe ngendlela encane zizoba isisekelo esibalulekile sobuchwepheshe obusebenza kahle, obuhlala isikhathi eside, nobuqhubekayo.
Uma ufisa, ngingavumelanisa lesi sihloko nesitayela sezemfundo (esinezingcaphuno), noma ngengeze izingxenye ezithile ezikhethekile njenge-nanograins vs. nanoprecipitates, ubudlelwano be-Hall-Petch, noma izifundo ze-alloys ezithile (Al, Ti, Ni, steel).
