Lub Sijhawm Tshiab Rau Titanium (1)
Ntawm cov hlau, titanium lub zog thiab lub teeb, corrosion kuj, thiab muaj peev xwm tiv taus qhov kub thiab txias tau ntev ntev nws tus nqi, tshwj xeeb tshaj yog rau qhov hnyav- thiab ib puag ncig-sensitive daim ntaub ntawv. Thaum nws thawj zaug piav nyob rau hauv lub xyoo pua 18th, ib tug co-discoverer hu ua hlau rau Titans - vajtswv yug los ntawm lub ntiaj teb thiab ntuj nyob rau hauv ancient Greek mythology.
Lub sij hawm tsuas yog hlawv titanium lub luster. Andrew Minor, tus xibfwb ntawm cov ntaub ntawv tshawb fawb thiab engineering hais tias "Kuv yog ib tus kws tshawb fawb txog cov ntaub ntawv, thiab qee zaum tib neeg nug kuv tias, 'Koj nyiam dab tsi?" Rau cov tsev, dav hlau, missiles, spaceships, thiab lwm yam, nws hais tias, "Yog tias koj xav tau cov khoom muaj zog tshaj plaws rau qhov hnyav tshaj plaws, nws yog titanium. Yog tias peb ua tau, peb yuav ua txhua yam tawm ntawm titanium."
Tseeb, rau cov neeg tsim khoom lag luam, qhov kev cia siab ntawm qhov muaj zog, lub teeb yuag, cov tsheb siv roj ntau, tsheb thauj khoom, thiab dav hlau, piv txwv li, lossis super corrosion-resistant cargo nkoj, titanium yuav tsum yog cov khoom ntawm kev npau suav.
Qhov teeb meem? "Nws kim dhau," Minor hais txog qib kev lag luam titanium lossis titanium alloys uas yuav hloov tau cov hlau thaum tsuas yog cov khoom muaj zog tshaj plaws, cov khoom siv ruaj khov yuav txaus. Tus nqi ntawm kev ua titanium yog li ntawm rau lub sijhawm ntau dua li ntawm cov hlau tsis muaj steel. Yog li ntawd, nws cov kev siv tau tseem txwv rau cov khoom tshwj xeeb rau aerospace, cov khoom siv high-end xws li cov hniav nyiaj hniav kub, lossis lwm yam kev siv niche.
Dab tsi ntxiv, ntshiab titanium tsuas muaj lub zog nruab nrab, Minor piav qhia. Nws tuaj yeem ntxiv dag zog nrog cov ntsiab lus xws li oxygen, aluminium, molybdenum, vanadium, thiab zirconium; Txawm li cas los xij, feem ntau ntawm cov nqi ntawm ductility - hlau lub peev xwm los kos los yog deformed yam tsis muaj fracturing.
Tam sim no, tom qab kaum xyoo ntawm kev tshawb fawb, lub sijhawm tshiab rau titanium, suav nrog cov ntawv thov kev tsim vaj tsev zoo heev, tuaj yeem tuaj txog, ua tsaug rau Minor thiab nws cov npoj yaig Berkeley, suav nrog Mark Asta, Daryl Chrzan, thiab JW Morris Jr., kuj yog cov xibfwb hauv Lub Tsev Haujlwm. ntawm Materials Science thiab Engineering. Lawv tau tshawb nrhiav thiab tsim cov titanium nyob rau hauv txhua txoj hauv kev hauv kev cia siab ntawm kev nthuav dav nws cov tswv yim siv rau ntau yam kev siv qauv lossis engineering.
Hloov chaw, dab tsi ua rau tus nqi ntau dhau ntawm kev lag luam-qib titanium, Minor piav qhia, yog cov txheej txheem Kroll nyuaj feem ntau siv los ua titanium tuav, ingots, thiab lwm yam hlau uas tuaj yeem tsim rau hauv cov khoom siv tau thiab lwm yam khoom. Cov txheej txheem suav nrog kev siv cov khoom kim heev xws li argon roj, thiab nws yog lub zog siv zog, xav tau ntau yam melts ntawm qhov kub siab heev, tshwj xeeb tshaj yog tswj cov pa oxygen impurities.
Tseeb tiag, titanium thiab oxygen muaj kev sib raug zoo, ib qho uas Minor, Asta, Chrzan, Morris, thiab cov npoj yaig xav kom nkag siab zoo dua. Pab neeg no paub tias cov pa oxygen impurity feem ntau yog siv rau titanium alloys los ua kom muaj zog ntxiv zog. Titanium ua nrog tsuas yog nce me me ntawm cov pa atomic oxygen tuaj yeem ua rau cov hlau muaj zog ntau ntxiv.
Hmoov tsis zoo, cov pa oxygen tuaj yeem ua rau muaj qhov txo qis hauv cov hlau ductility. Nws ua nkig thiab yuav tawg thiab tawg.
Tab sis "oxygen nyob txhua qhov chaw," Minor hais txog qhov nyuaj hauv kev ua haujlwm ntawm titanium lub siab ua haujlwm rau oxygen. "Nws tsis yog qee qhov impurity los ntawm cov khoom siv uas koj tuaj yeem zam tau."
Nws characterizes titanium rhiab heev rau oxygen li huab. Minor hais tias "Nws yog qhov txawv txav tiag tiag nws muaj zog npaum li cas," Minor hais. Nws ua rau muaj kev cuam tshuam rau cov hlau, ob qho tib si zoo thiab tsis zoo, thaum muaj cov pa oxygen zoo sib xws yog qhov tsis tseem ceeb rau cov hlau xws li txhuas thiab hlau vim tias nws tuaj yeem cuam tshuam nrog kev ua haujlwm yooj yim dua.
Txhawm rau kom paub ntau ntxiv, pab pawg tau tig mus rau kev ua haujlwm siab los ua qauv ntawm cov txheej txheem deformation hauv titanium nyob rau hauv kev ntxhov siab thiab sib txawv ntawm cov pa oxygen. Cov qauv khoos phis tawj, Asta hais tias, yog "cov cuab yeej muaj zog uas cia peb tshawb xyuas qhov kev sib tw zoo tshaj hauv titanium metallurgy."
Ntawm pab pawg cov kev tshawb pom loj, kev sib hloov ntawm cov pa oxygen atoms hauv titanium cov qauv siv lead ua thaum cov hlau nyob hauv kev ntxhov siab dhau los ua tus yuam sij rau kev nkag siab txog qhov poob ntawm ductility. Nyob rau hauv lub xeev uas tsis muaj kev ntxhov siab, cov pa oxygen molecules nyob tsis muaj xwm txheej nyob rau hauv qhov sib txawv ntawm cov atoms ntawm titanium. Tab sis nyob rau hauv cov neeg kho tshuab rog, cov pa atoms tuaj yeem hloov mus rau qhov chaw nyob ib sab uas lawv muaj kev tiv thaiv tsawg dua rau kev tsis sib haum xeeb uas, yog tias lawv kis tau, ua rau cov hlau tsis muaj zog.
"Cov pa oxygen txhawb kev ua haujlwm tsis muaj zog," Minor hais. Raws li cov neeg kho tshuab quab yuam deform cov hlau, cov pa oxygen atoms hloov chaw, tsis yog thaiv kev sib kis ntawm cov txheej txheem tsis xws luag, tuaj yeem pab txhawb qhov hu ua planar slip.
Asta hais tias, yog ib qho kev sib tsoo ntawm qhov tsis xws luag hauv cov hlau siv lead ua uas tsim ib qho ntawm lwm tus, nws thiaj li ua rau tawg, tawg, thiab nkig ntawm cov hlau.
Txhawm rau kom nkag siab tias qhov dislocation tuaj yeem tsim thiab sib kis hauv titanium li cas, Chrzan qhia pom kev sim txav cov ntaub pua plag loj.
"Cov ntaub pua plag loj heev tuaj yeem nqa ntawm ib kawg thiab rub hla hauv pem teb mus rau txoj haujlwm tshiab," nws hais. Tab sis lwm txoj hauv kev los txav cov ntaub pua plag yog tsim kom muaj ib qho ripple ntawm ib qho kawg thiab tom qab ntawd, los ntawm shuffling koj txhais taw hla saum cov ntaub pua plag, koj tuaj yeem "taug kev" lub ripple mus rau lwm qhov kawg. Muab tsis muaj dab tsi thaiv nws txoj kev txav mus los, tag nrho cov ntaub pua plag yuav raug tshem tawm los ntawm qhov deb sib npaug ntawm qhov dav ntawm lub ripple.
Xws li "ripples" hauv titanium tuaj yeem pom nrog electron microscopy. "Koj tuaj yeem pom tag nrho cov dislocations yog kab, hauv kab," Minor hais. "Thiab qhov ntawd tsis zoo rau ductility vim tias yog tias lawv kab thiab ua raws ib leeg xwb, lawv tsis tau tangled [thiab yog li nres] xws li cov hlau tsis ua hauj lwm nyuaj. Koj tau txais kev ntxhov siab, thiab qhov ntawd yog qhov koj tau txais. ib crack."
(Yuav tsum tau txuas ntxiv)
