Mechanical behavior of powdered iron aluminide Fe – 28Al manufactured by direct powder forging

Abstract

This study examines the impact of direct powder forging of powders on the composition, structure, and mechanical properties of iron aluminide Fe–28 at. % Al. During the synthesis and forging of Fe₃Al powders, a homogeneous A2 phase is formed at a temperature of 1100 °C. Porosity after forging is 2–2.5 %. Residual pores are predominantly planar in shape and are located at the boundaries of the powder particles. Annealing at 1300 °C improves the quality of interparticle boundaries and all samples exhibit transcrystalline fracture mechanism. Samples forged at 1100 °C and annealed at 1300 °C show maximum strength σ_bend = 1050 MPa and fracture toughness K_1c = 32.3 MPa·m^1/2. The yield strength demonstrates anomalous temperature sensitivity with a maximum of 400 °C and at 500 °C. Samples tested at 600 °C show a decrease in yield strength, but a high enough yield point σ_y ∼400 MPa and a high strengthening rate are very important for high-temperature creep resistance. In creep experiments at a load of 120 MPa at 600 °C, the strain rate varies in the range of 10⁻⁷–10⁻⁶ s⁻¹, the value of the rate sensitivity n ≈ 4. The main mechanism of creep is dislocation glide.