Titàn (Ti) ak alyaj li yo te resevwa atansyon toupatou nan aplikasyon pratik akòz pwopriyete ekselan yo tankou segondè fòs espesifik ak rezistans korozyon. Yo nan lòd yo amelyore pwopriyete yo mekanik nan metastable - alyaj Titàn, ranfòse presipitasyon se metòd ki pi efikas. Lè yo ajiste gwosè, mòfoloji, ak distribisyon HCP presipite nan matris BCC a, mouvman debwatman an anpeche nan koòdone / la. Sepandan, diferans ki genyen nan estrikti kristal, mekanis deformation, ak fòs ant la ak faz mennen nan gwo konsantrasyon estrès nan / koòdone a, ki se rezon ki fè yo pou lokalizasyon an souch gradyèl oswa diminisyon grav nan microcracks ak duktilite nan alyaj bifaz Titàn.
To address the aforementioned issues, three new strategies have recently been proposed. Firstly, activate various plastic mechanisms of the β phase during the plastic deformation process. For example, the activation sequence of the deformation mechanism of the β matrix from dislocation slip to phase transition is regulated by the precipitation of three functional groups α, thereby enhancing the ductility of the alloy. Secondly, constructing unique heterostructures to alleviate interfacial strain incompatibility, thereby achieving the strain distribution/gradient required for uniform plastic deformation. We have also developed layered structures with multi-scale alpha precipitates in biphasic titanium alloys to reduce stress concentration at the alpha/beta interface and improve ductility Thirdly, utilizing the interstitial O/N elements to refine and strengthen the alpha precipitate, thereby reducing the strength difference between the alpha and beta phases. However, the above three strategies rarely regulate the inherent deformation mechanism of low crystal symmetry alpha precipitates, and the independent slip systems of these precipitates are quite limited. Compared with the reported high-strength duplex titanium alloys (yield strength>1100 MPa), nouvo alyaj Titàn sa yo gen yon fòs sede ki depase 1500 MPa. Sepandan, akòz ensifizan travay redi kapasite ak pi ba elongasyon inifòm (<3%), these high-strength duplex titanium alloys still provide a balance between strength and ductility. The key to overcoming this dilemma lies in activating multiple plastic mechanisms of the alpha phase to alleviate strain incompatibility between the alpha and beta phases, improve work hardening rate (WHR), and achieve uniform elongation.
Anjeneral pale, mòd prensipal la glise debwatman nan alfa presipite se prismatikglise, kòm estrès taye kritik rezoud (CRSS) li se pi ba a nan mitan tout sistèm glise. Sepandan, konte sèlman sou sistèm glisman sa a pa ka adapte ak souch c-aks, ni li pa ka satisfè kritè Taylor von Mises la. Se poutèt sa, li nesesè aktive piramid ki gen fòm
Yo te obsève tranzisyon faz HCP a FCC pou estrès sa a nan alyaj Zr, Hf, ak Ti. Enspire pa konklizyon ki pi wo yo, nan travay sa a, nou te fèt yon mekanis sekans aktive milti plastisit (ki defini kòm SAPM) nan kouch alfa presipite milti-echèl Ti-4.5Al-4.5Mo{-7V-1.5Cr-1.5Zr (poids%) alyaj, ki gen yon bon efè duktilite. Lè yo kontwole jisteman gwosè patikil ak mòfoloji alfa presipite, yo te prepare yon alyaj twa pik Titàn ak milti-echèl ak milti kristalin alfa presipite. Lè w itilize mekanis deformation depandan gwosè grenn jaden an, SAPM opere nan kristal alfa milti-echèl pou adapte piti piti ak chaj aplike a. Estrateji sa a rezilta nan twa pik Titàn alyaj nou an ki gen yon gwo rannman / ultim fòs rupture nan 1550/1614 MPa ak yon duktilite nan apeprè 8.7%, depase deja rapòte segondè-fòs alyaj duplex Titàn.
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