Ultrafine-grained titanium alloys muab ntau qhov zoo tshaj plaws, nrog rau qib siab ntawm chav tsev kub thiab txias zog thiab elongation zoo nyob rau hauv high-temperature tensile daim ntaub ntawv. Grain refinement feem ntau yog ua tiav los ntawm qhov loj deformations, xws li sib npaug-angle extrusion, siab torsion, multi-axis forging, thiab cumulative coil welding. Ntxiv rau qhov no, kev kho hydrogen tuaj yeem siv rau titanium alloys.
Nyob rau xyoo 1970, Lub Tsev Haujlwm Saib Xyuas Kev Lag Luam Moscow tau kawm txog cov txiaj ntsig ntawm hydrogen ntawm kev ua cov khoom ntawm titanium alloys, muab tso rau pem hauv ntej lub tswvyim ntawm "hydrogen plasticization", nrog hydrogen ua ib ntus alloying caij, los ntawm hydrogen nkag mus, azeotropic decomposition, nqus dehydrogenation. thiab lwm yam txheej txheem, kev siv hydroplasticization, hydrogen theem hloov, thiab thim rov qab alloying ntawm hydrogen nyob rau hauv titanium alloys, los txhim kho cov txheej txheem, refine cov khoom microstructure, thiab refine cov khoom. Kev ua tau zoo, kho cov microstructure ntawm cov khoom.
Kev kho hydrogen tuaj yeem siv los ua kom zoo dua lub koom haum lis ntawm titanium alloy castings thiab forgings thiab txhim kho lawv cov khoom siv kho tshuab. Nws tau raug tshaj tawm nyob rau hauv cov ntaub ntawv hais tias kev kho hydrogen tuaj yeem kho qhov microstructure ntawm TiAl alloy, kom nws lub zog compression thiab lub zog tawm los tau zoo dua. Hauv kev xyaum, kev kho hydrogen feem ntau tuaj yeem ua ke nrog kev kho cua sov tom ntej thiab kev hloov pauv kub kom ua tiav cov qoob loo zoo heev. Nws tau raug pom tias qhov kub thiab txias, loj-teev deformation ntawm hydrogenated titanium alloys tuaj yeem ua rau tsim cov equiaxed zoo siv lead ua nrog cov nplej loj li ntawm 1 μm, lossis txawm tias cov nplej nanometer. Kev tshawb fawb ntawm Ti-6.3Al-3.5Mo-1.7Zr (%, pawg pawg) alloy pom tias: kev kho hydrogen hauv hydrogen atom feem ntawm 14% mus rau 16%, qhov deformation kub yog txo mus rau 550 degree, thiab tom qab ntawd los ntawm cov txheej txheem deformation thiab cov txheej txheem decomposition ntawm lub substable theem, qhov kawg grain loj ntawm 40 nm nano-grains tau txais. Muab piv rau engineering stress-strain curves ntawm Ti-6Al-4V alloys nrog ntau qhov ntau thiab tsawg, nws tuaj yeem pom tau tias cov khoom siv ultrafine-grained nthuav tawm lub zog siab thiab siab elongation piv nrog cov ntxhib-grained lossis general fine-grained khoom.
Kev kho mob ntawm kev tso cai rau titanium alloys kom nqus tau ntau ntawm hydrogen atoms (protium) thiab tom qab ntawd tso cai rau cov hydrogen atoms (protium) kom desorb ntawm qhov kub thiab txias hauv lub tshuab nqus tsev yog hu ua protium kho. Rau + hom titanium alloys, cov kev kho mob protium muaj peb txheej txheem hauv qab no: (1) protium nqus dej hauv qhov chaw hydrogen; (2) martensitic transformation thiab thermal ua thaum kawg inducing diffuse hydride nag lossis daus; thiab (3) kawg protium desorption kho thiab recrystallization. Nws tau tshaj tawm tias kev kho protium ntawm Ti-6Al-4V alloy, uas absorbed 0.5% protium thiab desorbed ntawm 873 K, pom ib lub koom haum ultrafine isotropic crystalline nrog loj angular grain ciam teb. thiab grain loj nyob rau hauv thaj tsam ntawm 300-500 nm. Nws tau pom tias txoj kev kho protium nce cov ntsiab lus ntawm theem hauv matrix. Kev ntsuam xyuas tensile pom tau tias muaj kev nce ntxiv ntawm qhov muaj zog ntawm cov hlau nyob rau hauv chav tsev kub, thaum lub siab tshaj plaws elongation ntawm cov hlau ntawm 1123 K mus txog 90{{20}}0%. Nws kuj tau tshaj tawm tias kev kho protium ntawm Ti-6Al-4V daim ntawv nrog 0.5% cov ntsiab lus protium, tom qab ntawd quenching ntawm 1223 K, kub dov ntawm 1023 K mus rau thickness txo ntawm 80%, thiab protium desorption ntawm 873 K ntse tsim ib lub koom haum homogeneous nrog ultrafine isometric crystals nrog grain loj li ntawm 0.3 mus rau 0.5 μm. Kev ntsuam xyuas tau pom tias cov khoom siv kho tshuab xws li superplastic elongation ntawm cov hlau zoo tuaj nrog qhov txo qis ntawm cov nplej loj.
Txawm hais tias txoj kev kho hydrogen qhia tau hais tias muaj peev xwm zoo rau kev kho cov titanium alloys, nws yog tus nqi ntau dua li lwm txoj hauv kev, thiab rau cov qauv loj dua, txoj kev kuj tseem muaj teeb meem xws li tsis sib xws hydrogen faib thiab cov khoom siv siab, uas yuav tsum tau tshawb xyuas ntxiv thiab. daws.
