Phase transformations and phase stability in the Ti–44 at.%Al–(0–7 at.%)Mo system

Alloying Elements in Intermetallic γ‐TiAl Based Alloys – A Review on Their Influence on Phase Equilibria and Phase Transformations

“…[165,166] An α ! β þ γ reaction was also observed by Musi et al [163] in an as-cast Ti-44Al-5Mo (at%) alloy. This reaction resulted in coral-like structures, which occurred in the former α grains next to lamellar structures arising from the α !…”

“…Consequently, the superstructure peaks associated with the ordered crystal structure of the β o phase become undetectable at lower temperatures during heating experiments and the disordering temperature appears to be lower compared to the ones measured by neutron diffraction. [112,163] Generally, a large body of literature exists on the effect of Mo regarding the phase transformation pathways of γ-TiAl based alloys. [23,162,[164][165][166][167][168][169] For instance, Singh and Banerjee [165,166] investigated the Ti-(44-50)Al-(2, 4, 6)Mo (at%) alloy system with respect to its microstructural evolution during solidification and subsequent heat treatments.…”

“…Additionally, indications of a direct precipitation of the γ phase from the β phase during cooling were also found in the microstructure. [163] In the case of a β-homogenized and waterquenched Ti-44Al-7Mo (at%) alloy, Erdely et al [169] traced such a β o ! γ transformation from the metastable to the stable state heating as determined by neutron diffraction (blue, 3 and 7 at% Mo) and high-energy X-ray diffraction (green, 5 at% Mo), respectively.…”

On the Temperature‐Induced Equilibration of Phase Distribution and Microstructure in a Gas‐Atomized Titanium Aluminide Powder

“…The chemical composition of this model alloy, i.e., Ti-46.3Al-2.2W-0.2B (at%), allows to close some gaps in the knowledge of the phase transformation behavior in the Ti-Al-W system, for which only a few studies are available in the literature, especially when compared to Nb-and Mo-containing alloys. [15][16][17][18][19][20][21][22] Additionally, the chemical DOI: 10.1002/adem.202201242 Powder production by gas atomization of γ-TiAl based alloys typically yields a highly nonequilibrium material regarding the occurring phases and their microstructural appearance. In particular, the equilibration of the powder and the associated phase transformations during heating are of great importance for the subsequently applied densification techniques.…”

“…The chemical composition of this model alloy, i.e., Ti–46.3Al–2.2W–0.2B (at%), allows to close some gaps in the knowledge of the phase transformation behavior in the Ti–Al–W system, for which only a few studies are available in the literature, especially when compared to Nb‐ and Mo‐containing alloys. [ 15–22 ] Additionally, the chemical composition of this model alloy was chosen in accordance with those of other W‐containing γ‐TiAl based alloys, e.g., the ABB‐2 alloy [ 23 ] and the IRIS alloy. [ 1,11 ] Concerning the conducted experiments, in situ high‐energy X‐ray diffraction (HEXRD), which is a proven tool for the investigation of γ‐TiAl based alloys, [ 24 ] allows the reliable monitoring of the changes of the phase distribution and lattice parameters as well as the observation of the ordering behavior of selected phases in a time‐resolved manner during heating of the powder.…”