Cast and PM processing development in gamma aluminides

Development of a TiAl Alloy by Spark Plasma Sintering

“…Our approach was to use a strong strengthener element which was counter-balanced by a high aluminum content in order to maintain an adequate microstructure in particular for tensile ductility. For instance, Thomas et al [28] has found that in as-Hipped condition, GE-48 exhibits a higher ductility than GE-47. Moreover, a TNM alloy processed by SPS [29] exhibits a very high strength at room and high temperatures but a limited ductility (0.9% of plastic elongation).…”

Centrifugal casting of TiAl exhaust valves

“…The research results [16] indicated that the mechanical properties of the TiAl alloy casting were mainly related to cast features. The mechanical properties could not be easily optimized by any additional post-HIP heat treatment.…”

Microstructural Development and Mechanical Properties of PM Ti–45Al–2Nb–2Mn–0.8 vol.%TiB2 Processed by Field Assisted Hot Pressing

“…In addition, alloying with B leads to a microstructure refinement [11,12] . Many studies has been reported, showing the possibility to tune the microstructure and mechanical properties with a combination and differing amounts of these elements [12][13][14][15][16] .…”

“…The most popular processing routes that have been explored so far are a combination of casting, thermomechanical and/or heat treatments and powder metallurgy (PM) [15,[17][18][19][20] . Even though, casting is the best established process, it suffers from several drawbacks such as choosing proper composition in order obtain good melt fluidity, casting defects, segregation of alloying elements, poor workability, need for post consolidation, heat treatments, etc [19,21] .…”

“…Even though, casting is the best established process, it suffers from several drawbacks such as choosing proper composition in order obtain good melt fluidity, casting defects, segregation of alloying elements, poor workability, need for post consolidation, heat treatments, etc [19,21] . To overcome some of these drawbacks several new techniques such as counter-gravity and centrifugal casting techniques have been developed, even then these techniques heavily depends on the prior knowledge of the equilibrium phase diagram and further optimization of heat treatments [15] . Compared to the casting route, PM offers several advantages such as refining the microstructure, improving structural and chemical homogeneity and providing freedom of choosing composition and initial raw materials, reducing the need to separate heat treatments and directly obtaining final product shape requiring minimal post processing treatments.…”