Abstract
High-Nb-containing TiAl (High Nb-TiAl) alloys are considered as a new generation of TiAl alloys for applications at higher temperatures. However, their poor room-temperature (RT) mechanical properties, such as near-zero plasticity, significantly limit their applications. To promote the practical applications of high Nb-TiAl alloys, this study investigated the utilization of Si alloying to improve the mechanical properties of these alloys by in situ precipitation of micro-/nanosilicides during the casting process. In particular, S segregation and equiaxed γ grains can improve the plasticity of the alloy, whereas micro-/nanosilicides can strengthen the alloy via the second-phase strengthening effect. The combined effects of S segregation and the ability to generate high-density silicides result in simultaneous enhancement of ultimate tensile strength and plasticity of the alloy at RT and 850 °C.
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