Abstract
A primary challenge associated with TiAl alloys is their low ductility at room temperature. One approach to overcome this flaw is attaining ultrafine grains in the alloy’s final microstructure. The powder metallurgy (PM) processing route favours the synthesising of ultrafine grains in TiAl alloys. This paper features the mechanical alloying (MA) process and rapid consolidation through the spark plasma sintering (SPS) technique, which comprises the PM process. Furthermore, a second approach discussed covers microalloying TiAl alloys. An evaluation of the influence of high oxygen content is also presented, including the formation of α-Al2O3. A section of the review delves into the dynamic recrystallisation mechanisms involved in elevated temperature deformation of TiAl alloys. The final section highlights the efficacy of ternary element additions to TiAl alloys against oxidation.
Highlights
Intermetallics are described as an ordered alloy phase formed between two metallic elements
Titanium aluminides (TiAl), over the years, have been some of the most interesting and highly researched lightweight structural materials. ey have been envisaged in replacing nickel-based superalloys (NBSAs) for certain stress and temperature application ranges. e alloy design concept is quite similar to that of NBSAs
TiAl alloys exhibit a combination of enviable properties such as low density (∼ 3.9–4.2 g·cm− 3), high melting point of 1733 K, high strength to weight ratio that can be retained at temperatures up to 973 K, high elastic moduli, low diffusion coefficient, good creep properties up to 1173 K, and substantial resistance to corrosion and oxidation
Summary
Intermetallics are described as an ordered alloy phase formed between two metallic elements. An alloy is said to be ordered provided two or more sublattices are needed to describe its atomic structure [1]. Titanium aluminides (TiAl), over the years, have been some of the most interesting and highly researched lightweight structural materials. E alloy design concept is quite similar to that of NBSAs. Titanium aluminides exhibit an ordered α2(Ti3Al) and c(TiAl) phases, analogous to that of NBSA’s L12 ordered phase. TiAl alloys exhibit a combination of enviable properties such as low density (∼ 3.9–4.2 g·cm− 3), high melting point of 1733 K, high strength to weight ratio (up to 1000 MPa) that can be retained at temperatures up to 973 K, high elastic moduli, low diffusion coefficient, good creep properties up to 1173 K, and substantial resistance to corrosion and oxidation. Compared to ceramics, they exhibit good thermal conductivities and are ductile at their service temperatures while maintaining good structural stability [2, 3]
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