Microstructure and Properties of Boride‐Strengthened Titanium‐Alloyed Iron Aluminides Processed by Direct Powder Forging Under Dynamic Recrystallization

Powder alloys Fe–28Al strengthened with Ni 3 B, CrB 2 , or B 4 C and consolidated by direct powder forging at 1150°C under dynamic recrystallization (DRX) develop an ultrafine microstructure with matrix grains of 1–2 µm and boride particles of 50–100 nm. The alloy containing 0.59 vol.% CrB 2 exhibits exceptional room‐temperature properties: a compressive yield strength of 1176 MPa, a bending strength of 2029 MPa, 3% ductility, and a fracture toughness of 48.6 MPa·m 1/2 , exceeding all known analogs. At 700°C, boride dispersion ensures a high yield stress of ≈450 MPa, while the steady‐state creep rate under 120 MPa is 3.3 × 10 −7 s −1 . Comparative creep tests at 700°C–750°C show that alloys with higher CrB 2 content exhibit lower creep rates due to reduced grain‐boundary strengthening at elevated temperatures and the increasing contribution of Coble diffusion. A newly developed Fe–Al–Ti–CrB 2 alloy demonstrates excellent creep resistance at 800°C (2.7 × 10 −7 s −1 at 120 MPa). Iron aluminide strengthened with LaB 6 maintains a low creep rate of ≈10 −6 s −1 even at 850°C. These results confirm the effectiveness of combined DRX grain refinement and boride dispersion strengthening in achieving high‐strength, creep‐resistant Fe–Al intermetallics suitable for high‐temperature applications.