Influence of Yttrium on the Phase Composition of the Ti-Al System Obtained by the ‘Hydride Technology’

Abstract

In this study, the influence of yttrium on the formation of the structural-phase state of the Ti-Al alloy, obtained by the “hydride technology” (GT) method, has been analyzed. Using transmission electron microscopy (TEM) and X-ray spectral microanalysis, the authors of the work have established the following phases formed in the sample volume and on the surface: Ti3Al, TiAl, Al, α-Ti, Ti3Al5, Y2Al, Y5Al3, YAl3, YAl, and Y6Ti4Al43. The lamellar structure has been formed in the alloy volume. The average width of the Al-rich lamellae was 0.36 µm and that of the Ti-rich lamellae was 0.21 µm. The formation of a triple Y6Ti4Al43 phase, which is localized along the boundaries of the lamellar structure, has been recorded. The localization scheme of the formed phases of the TAY alloy has been proposed.

Influence of Dy and Ho on the Phase Composition of the Ti-Al System Obtained by ‘Hydride Technology’

“…In the material, there are unevenly distributed areas with a predominance of Dy (luminous areas in black-white image) up to 300 μm in size. The consequence of the modifying effect of Dy is a relatively larger average grain size (150 µm) of the studied experimental Dy-containing gamma alloys in contrast to alloys with Sc and Y microadditives (100 µm) [ 35 , 36 ]. Grains with an average size of 110–130 µm were formed on the TAH specimen surface.…”