Abstract
The effect of Y2O3 nanoparticles on microstructure and high-temperature mechanical properties of Ti–48Al–2Cr–2Nb alloy prepared by directed energy deposition was investigated. Cracks in the TiAl alloy sample were eliminated by a new directed energy deposition method with a preheating unit. The results indicated that the microstructure of TiAl alloy without Y2O3 nanoparticles addition was composed primarily of (α2/γ) lamellar colony. While the equiaxed γ phase was generated within the (α2/γ) lamellar colony and on the colony boundaries, and the microstructure exhibited a duplex structure due to the 0.5 wt% nano-Y2O3 addition, and the grain size was decreased from 183 μm to 25 μm. The ultimate tensile strength and fracture elongation tested at 750 °C were enhanced simultaneously from 615.1 to 805.7 MPa and from 5.56% to 7.40%, respectively, by 0.5 wt% Y2O3 nanoparticles addition. Finally, the strengthening mechanism and microstructure refinement mechanism were discussed in detail. This investigation provides a valuable reference for TiAl alloy fabrication and widespread engineering applications.
Published Version
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