Hydrogen-Induced Phase Transformation and Microstructure Evolution for Ti-6Al-4V Parts Produced by Electron Beam Melting

Metals

Olga Perevalova¹  Natalia Pushilina²  Roman Laptev²  Viktor Kudiiarov²  Egor Kashkarov²  Maxim Syrtanov²  Alexey Panin²  Andrey Lider²  Andrey Koptyug³ 

[1] Institute of Strength Physics and Materials Science of Siberian Branch of Russian Academy of Sciences, Tomsk 634055, Russia;School of Nuclear Physics, National Research Tomsk Polytechnic University, Tomsk 634050, Russia;Sports Tech Research Centre, Mid Sweden University, Akademigatan 1, SE-831 25 Östersund, Sweden;

关键词: electron beam melting;    additive manufacturing;    titanium Ti-6Al-4V alloy;    hydrogen;    microstructure;    phase transitions;   

DOI  :  10.3390/met8050301

来源: DOAJ

【 摘 要 】

In this paper, phase transitions and microstructure evolution in titanium Ti-6Al-4V alloy parts produced by electron beam melting (EBM) under hydrogenation was investigated. Hydrogenation was carried out at the temperature of 650 °C to the absolute hydrogen concentrations in the samples of 0.29, 0.58, and 0.90 wt. %. Comparative analysis of microstructure changes in Ti-6Al-4V alloy parts was performed using scanning electron microscopy (SEM), transmission electron microscopy (TEM), and X-ray diffraction (XRD). Furthermore, in-situ XRD was used to investigate the phase transitions in the samples during hydrogenation. The structure of Ti-6Al-4V parts produced by EBM is represented by the α phase plates with the transverse length of 0.2 μm, the β phase both in the form of plates and globular grains, and metastable α″ and ω phases. Hydrogenation to the concentration of 0.29 wt. % leads to the formation of intermetallic Ti3Al phase. The dimensions of intermetallic Ti3Al plates and their volume fraction increase significantly with hydrogen concentration up to 0.58 wt. % along with precipitation of nano-sized crystals of titanium δ hydrides. Individual Ti3Al plates decay into nanocrystals with increasing hydrogen concentration up to 0.9 wt. % accompanied by the increase of proportion and size of hydride plates. Hardness of EBM Ti-6Al-4V alloy decreases with hydrogen content.

【 授权许可】

Unknown