Harbin Institute of Technology, Harbin, China

Botao Jiang, Independent Expert
Xu Liu, Independent Expert
Baoxian Su, Doctot of Engineering Sciences, Professor
Yanqing Su, Doctot of Engineering Sciences, Professor, e-mail: suyq@hit.edu.cn

Titanium alloys are in great demand in the field of materials science and engineering due to their enhanced mechanical properties, high corrosion resistance and biocompatibility. Heat treatment of titanium alloys is necessary to achieve the maximum level of mechanical and other properties due to a certain effect on phase transformations. However, determining the optimal type of heat treatment for a particular alloy is not an easy task, requiring a lot of time and experiments. The generally accepted approach is based on the diagnosis of the material after its processing in order to establish the final microstructure and properties, which is a laborious process. Optimization of heat treatment of a metastable β-titanium alloy obtained by vacuum-arc remelting is considered. Using the in-situ observation of phase transformations in an alloy at high temperatures performed on a laser scanning confocal microscope, the optimal temperature of its heat treatment was determined to achieve maximum material strength, which was 800 ^оC. The hypothesis was confirmed in the course of studies using scanning electron and transmission electron microscopy, as well as in the process of tensile testing of alloys. The experimental results showed that the primary α-phase was released along several orientations during the solid solution treatment, and the nanoscale secondary α-phase, released during the aging treatment, was evenly distributed. The strength test results showed that after processing a solid β-solution at a temperature of 800 ^оC, compared with other temperatures, the alloy has the highest tensile strength, which confirms the reliability of using the in-situ observation. The practical significance of this study lies in the possibility of applying its results to optimize the heat treatment of β-titanium alloys.

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