Effect of Heat Treatment on Microstructure and Properties of Fe(Al,Ta)/Fe₂Ta(Al) Eutectic Composite

Fe(Al,Ta)/Fe₂Ta(Al) eutectic composites with solidification rates of 6, 20, 30, and 80 µm/s were prepared by a modified Bridgman directional solidification technology. The coarse Fe₂Ta(Al) Laves phase was precipitated at the eutectic colony boundary during the solidification process, which can affect the stability of microstructure and properties of the composites. The coarse Laves phase was refined using different heat treatment processes in the present paper. The influences of different heat treatment parameters on the Laves phase content, lamella/rod spacing, and mechanical properties were investigated in detail. In addition, the corrosion behaviors of Fe(Al,Ta)/Fe₂Ta(Al) eutectic composites before and after being annealed heat treatment in a 3 g/L Na₂S₂O₃ solution were also studied. It is shown that both the content of Laves phase and lamella/rod spacing are gradually decreased after heat treatment. Micro-hardness is decreased, while the yield strength, compressive strength, and corrosion resistance are improved. The optimum heat treatment process is selected as well.