Improvement of the structure and mechanical characteristics of structural intermetallides of the titanium-aluminium system at the directional solidification

Lobanov, LM
1Asnis, EA
1Piskun, NV
1Statkevich, II
1E.O. Paton Electric Welding Institute of the NAS of Ukraine, Kyiv
Dopov. Nac. akad. nauk Ukr. 2018, 12:51-60
https://doi.org/10.15407/dopovidi2018.12.051
Section: Materials Science
Language: Russian
Abstract: 

The paper presents the results of investigation of the processes of structure formation and the mechanical properties at the directional solidification of a β-stabilized intermetallic alloy of the titanium-aluminium systems. It is shown that the use of the directional solidification at a crucibleless induction zone melting produces a specific microstructure of alloy Ti-44Al-5Nb-3Cr-1.5Zr (at. %). It is established that the thermal gradient and the rate of solidification in the directional crystallization are the basic thermodynamic tools that make it possible to form an ordered microstructure. Investigations showed that, at the speed of 150 mm/h, the temperature gradient reaches 300 C · cm–1. This leads to the ordering and orientation of the secondary phase microstructure of the material and to the improvement of its physico-mechanical properties. Regulation of the microstructure allows an essential improvement of the high-temperature mechanical properties, namely ultimate strength, Young's modulus, and creep resistance. The results showed that the temperature limit of the structural applicability of alloys of this type can be expanded from 750-800 °C up to 900-950 °C.

Keywords: directional solidification, intermetallide, mechanical characteristics, structure, zone melting
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