Abstract: Gradient structure is emerging as an effective strategy to fabricate metals with remarkable mechanical performance, but have not been verified in intermetallic compounds for high-temperature applications. Through experiments and atomic simulations, we show that a typical intermetallic TiAl alloy with gra-dient structure has a significant strengthening effect both at room temperature and high temperatures. The room-temperature compressive strength of TiAl alloys with gradient grain obtained by additive man-ufacturing is 2.57 GPa, which is ∼2.7 times as strong as that with equiaxed grain. The strengthening effect is attributed to more sessile dislocations in gradient structure caused by the intersections of mul-tiple slip systems in gradient grain. More importantly, the strengthening effect is still effective at high temperatures and the compressive strength is 1.28 GPa at 750 °C. The simulation results show that this strengthening effect is due to the increased Hirth dislocation at high temperatures. This study expands the applications of TiAl alloys for load-bearing structures and provides a new strategy for improving the strength of intermetallic compounds at both room temperature and high temperatures.

Key words: TiAl alloys, Strengthening, Gradient grain, Additive manufacturing, Molecular dynamics