Microstructure and fracture toughness of the Bridgman directionally solidified Fe-Al-Ta eutectic at different solidification rates

Fe-Al-Ta eutectic composites were obtained by a modified Bridgman directional solidification technique at different solidification rates. Solidification microstructure transforms from regular eutectic to eutectic colony with the increase of the solidification rate. The solid/liquid interface of Fe-Al-Ta eutectic evolves from planar interface to cellular interface with the increase of the solidification rate. In addition, three-point bending method was adopted to study the room-temperature fracture toughness of the as-cast Fe-Al-Ta eutectic alloy and the Fe-Al-Ta eutectic composites. Moreover, the fracture morphologies, the crack propagation path and the strengthening mechanism of Fe-Al-Ta eutectic were discussed.