Optimization of the composition and heat treatment of the cast biocompatible Ti–18Nb–xSi alloys

1Shevchenko, OM
1Kulak, LD
1Datskevich, OV
1Kuzmenko, NN
1Khomenko, GE
1Firstov, SA
1I. M. Frantsevich Institute for Problems of Materials Sciences of the NAS of Ukraine, Kyiv
Dopov. Nac. akad. nauk Ukr. 2016, 2:62-68
Section: Materials Science
Language: Ukrainian
The investigation of cast alloys of the $\rm Ti{-}Nb{-}Si$ system with a silicon content of 2% is carried out comparing to the binary alloy $\rm Ti{-}1{\%}\,Si$. The effects of silicon and the quenching temperature on the structure and hardness of the alloys are studied. The studies have shown that, in the alloy $\rm Ti{-}1{\%}\,Si$ and ternary alloys $\rm Ti{-}18Nb{-}\mathit{x} Si$ ($x = 0.6 \div  1.2{\%}$), the martensitic structure of different morphologies and dispersions is formed during the hardening, depending on the heat temperature. In the binary alloy, the large or massive lamellar $\alpha$-phase is formed, while niobium promotes the appearance of $\alpha''$-martensite and the transition to the packet thin plate or needle lens form. The X-ray analysis showed the presence of $\rm Ti_3Si$ silicide in the alloys, the quantity of which depends on the silicon content and quenching temperature. Maximum hardness achieved with the silicon content of 0.8–1.1% and quenching temperatures 1100–1200 ºC.
Keywords: hardness, martensite, quenching, silicides, structure, Ti-Si, titanium alloys
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