Enhanced compressive creep properties of a Y2O3-bearing Ti–48Al–2Cr–2Nb alloy additively manufactured by electron beam powder bed fusion.

Electron beam powder bed fusion (EBPBF) was used to fabricate a Ti–48Al–2Cr–2Nb alloy incorporated with 0.2 wt% Y 2 O 3 nano-ceramic powders. Spherical Y 2 O 3 nanoparticles with the particle size of 20–40 nm were uniformly distributed throughout the as-built TiAl alloy, and the average particle size was 30 nm. The effect of Y 2 O 3 nanoparticles on compressive creep properties was investigated and the creep tests were performed at 750 and 800 °C, respectively, with a stress of 250 MPa. The results showed that the compressive creep properties were significantly improved by Y 2 O 3 nanoparticles. After 50h creep test at 800 °C, the maximum creep strain decreased from 59.22% for the Y 2 O 3 -free alloy to 28.08% after the incorporation of Y 2 O 3 nanoparticles, and the minimum creep rate decreased from 2.56 × 10−6 s−1 to 1.53 × 10−6 s−1 correspondingly. The maximum creep strain and minimum creep rate of the Y 2 O 3 bearing Ti–48Al–2Cr–2Nb alloy were 110.9% and 67.3% lower than those of the Y 2 O 3 -free alloy at 800 °C, respectively. The content of high angle grain boundary (HAGB, >15°) increased from 62.1% to 92.9% with the creeping temperature increasing from 750 °C to 800 °C for free-particle TiAl alloy. Large amounts of fine recrystallized grains were observed for Ti–48Al–2Cr–2Nb alloy after 50h creep test at 800 °C, while the recrystallization was prevented by Y 2 O 3 nanoparticles addition. Finally, the effect of Y 2 O 3 nanoparticles addition on the strengthening mechanism and recrystallization behavior of TiAl alloy was discussed. This work suggested that the high-temperature performance of TiAl alloy can be tailored by the incorporation of highly thermal-stable Y 2 O 3 nanoparticles in EBPBF, which is likely to enhance the service temperature of additively manufactured TiAl alloy for high temperature critical applications. [ABSTRACT FROM AUTHOR]