Titanium alloys nyob hauv ib qho chaw tshwj xeeb hauv cov khoom siv. Ntshiab titanium, txawm tias nws zoo heev corrosion kuj thiab biocompatibility, tsuas muaj lub zog nruab nrab (kwv yees li 240-550 MPa tensile zog). Kev hloov pauv ntawm titanium los ntawm cov khoom lag luam ntshiab mus rau qhov siab -cov khoom siv engineering- muaj peev xwm ntawm 1500+ MPa yield zog- yog tag nrho hauv nws cov kev cuam tshuam nrog cov ntsiab lus alloying los ntawm thoob plaws lub sij hawm.
Tsis zoo li cov hlau los yog txhuas alloys, qhov kev txhim kho cov txheej txheem feem ntau vam khom ntawm cov ntsiab lus nqaim, titanium nthuav tawm qhov txawv txav tsis zoo ntawm cov vaj tse. Ntau tshaj 60 lub ntsiab lus hloov kho titanium theem equilibria, hloov pauv kinetics, thiab cov lus teb txhua yam. Cov ntsiab lus no tsis raug xaiv; lawv lub luag haujlwm yog txiav txim siab los ntawm qhov tseem ceeb crystallographic compatibility, hluav taws xob qauv, thiab lawv txoj hauj lwm txheeb ze rau titanium nyob rau hauv lub periodic rooj.
Tsab ntawv xov xwm no muab cov kev tshuaj ntsuam xyuas seb yuav ua li cas tsev neeg "ntau-tus khub" ua haujlwm "ntawm-kev thov kev thov"- los ntawm Al-V ua ke ua ke dominating aerospace daim ntawv thov mus rau refractory hlau ntxiv thawb kev pabcuam kub tshaj 600℃.
Lub Metallurgical moj khaum: Vim li cas Titanium teb rau ntau yam
1.1 Allotropic Hloov pauv raws li tus qauv tsim
Titanium's versatility originates los ntawm nws allotropic transformation. Hauv qab 882 degree, ntshiab titanium crystallizes nyob rau hauv ib hexagonal ze-packed (HCP) qauv, xaiv raws li -Ti. Tshaj qhov ntsuas kub no, nws hloov mus rau lub cev -centered cubic (BCC) -Ti .
Qhov kev hloov pauv kub no-thiab qhov ruaj khov ntawm txhua theem- tau hloov pauv loj heev los ntawm kev sib ntxiv alloying. Cov ntsiab lus uas nce qhov -transus kub nthuav dav -theem teb thiab raug hu ua -stabilizers. Cov ntsiab lus uas cuam tshuam rau -transus kub nthuav dav -theem teb thiab raug hu ua -stabilizers . Ib pawg thib peb, cov ntsiab lus nruab nrab, ua kom muaj kev cuam tshuam tsawg kawg nkaus ntawm qhov kev hloov pauv kub.
Cov txheej txheem kev ruaj ntseg theem no ua rau kev tsim kho microstructural thoob plaws ntau qhov teev: thawj qhov loj me, theem nrab lath thickness, grain morphology, thiab kev faib tawm ntawm cov khoom sib txuas.
1.2 Qhov System Classification
Raws li lawv cov kev cuam tshuam nrog titanium's allotropic transformation, alloying ntsiab faib ua plaub pawg ua haujlwm:
| Qeb | Cov ntsiab lus |
Qhov cuam tshuam rau -Transus |
Hom Concentration Range |
| -stabilizers | Al, Ga, Ge, B, O, N, C | Nce |
l: 2-7 wt%; O: 0.1-0.3 hli |
| -stabilizers (isomorphous) | Mo, V, Nb, Ta, W | Txo qis |
V: 2–15 wt%; Nb: 10-40 wt% |
| -stabilizers (eutectoid) | Fe, Cr, Ni, Cu, Si, H | Txo qis |
V: 2–15 wt%; Nb: 10-40 wt% |
| Cov ntsiab lus nruab nrab | Zr, Hf, Sn | Kev hloov tsawg kawg nkaus |
Zr: 1–8 wt%; Qhov hnyav: 2-5% |
Daim duab 1 qhia txog cov yam ntxwv ntawm binary theem kab kos rau txhua pawg, qhia tias qhov sib ntxiv ntawm cov alloying ntxiv li cas reshape theem ciam teb thiab pab kom sib txawv microstructural tshwm sim.
-Stabilizers: Lub Zog thiab Oxidation Foundation
2.1 Aluminium: Lub Universal Strengthener
Aluminium yog feem ntau siv alloying caij hauv titanium, tam sim no nyob rau hauv yuav luag tag nrho cov lag luam alloys los ntawm Ti-6Al-4V rau high-temperature ze- alloys. Nws dominance yog los ntawm ntau qhov kev koom tes:
· Cov tshuaj tiv thaiv kom muaj zog: Al dissolves nyiam nyob rau hauv -theem, occupying chaw hloov chaw nyob rau hauv HCP lattice. Qhov no ua rau ob qho kev txhawb zog ntxiv: (1) lattice distortion nce kev tiv thaiv rau kev txav txav, thiab (2) kev hloov kho ntawm -theem stacking txhaum lub zog.
· txo qhov ceev: Ntawm 2.7 g / cm³, Al ho txo qis alloy ntom. Txhua 1 wt% Al ntxiv txo qhov ceev los ntawm kwv yees li 1.5%, qhov txiaj ntsig tseem ceeb rau kev siv aerospace qhov twg lub zog tshwj xeeb dictates cov qauv tsim.
· Kev txiav txim muaj peev xwm: Ntawm qhov ntau tshaj li ntawm 8 wt%, Al txhawb kev tsim cov xaj xaj ₂ (Ti₃Al) precipitates. Thaum cov no tuaj yeem embrittle cov hlau yog coarsely faib, tswj nag lossis daus muaj kev ntxiv dag zog ntxiv.
Kev ua haujlwm tsis ntev los no los ntawm Huang et al. qhia tau tias Al ntxiv hauv paus hloov tus cwj pwm dislocation hauv titanium. Hauv binary Ti-6Al alloys, Al suppresses deformation twinning thiab hloov kho qhov tseem ceeb daws teeb meem shear stress (CRSS) rau ntau lub tshuab plam. Qhov kev txhawb zog no los nrog kev lag luam tawm: thaum lub zog tawm los nce, ductility thiab kev cuam tshuam toughness feem ntau txo.
2.2 Interstitial Strengtheners: Oxygen, Nitrogen, Carbon
Oxygen, nitrogen, thiab carbon nyob rau hauv qhov chaw interstitial nyob rau hauv lub titanium lattice, ua kom muaj zog ntxiv zog ntawm tsawg concentrations. Txhua 0.1 wt% O nce yield zog los ntawm kwv yees li 150-200 MPa.
· Oxygen: Raws li feem ntau interstitial, O yog ob qho tib si muaj zog thiab muaj kev txhawj xeeb txog kev sib kis. Oxygen stabilizes lub -theem, tsa lub -transus kub, thiab muab cov khoom muaj txiaj ntsig zoo ntxiv. Txawm li cas los xij, tshaj li ntawm 0.3-0.4 wt% O induces hnyav embrittlement los ntawm kev tsuj ntawm ductile deformation mechanisms.
· Nitrogen: Kev nce qib tsis ntev los no tau rov xav txog N lub luag haujlwm. Zhang et al. pom tau hais tias tswj N ntxiv (0.17–0.40 wt%) ua ke nrog grain ciam engineering tuaj yeem tsim lub zog tshwj xeeb -kev sib txuas ua ke. Lawv Ti-1800 alloy (Ti-4.1Al-2.5Zr-2.5Cr-6.8Mo-0.17O-0.10N) ua tiav 1800 MPa yield zog los ntawm cov qauv hierarchical ntawm thawj, theem nrab, thiab ultrafine -Widmanstätten precipitates.
Carbon: Ntxiv ntawm 0.05–0.2 wt% C txhawb kev tsim TiC. Cov carbides no ua haujlwm ob npaug: (1) pinning cov ciam teb thaum lub sij hawm siab -kub ua, refining lub microstructure zaum kawg, thiab (2) ua raws li heterogeneous nucleation qhov chaw rau nag lossis daus. Qhov tshwm sim microstructure qhia pom cov nplej zoo dua thiab ntau qhov sib txawv ntawm lub lath orientations.
2.3 Boron: Grain Refinement Agent
Microalloying nrog B (0.01–0.2 wt%) tsim TiB whiskers uas ua kom zoo dua qub nplej loj. Nyob rau hauv TA6.5 alloys, 0.2 wt% B hloov lub microstructure los ntawm ntxhib Widmanstätten rau refined pob tawb -weave morphology, txo cov colony loj thiab txhim kho ob chav - kub thiab 650℃tensile zog .
Txuas ntxiv...
