Characterization of Fe3Al-based intermetallic alloys fabricated by mechanical alloying and HIP consolidation

Fe3Al-based alloys with and without Ti addition were synthesized by hot isostatic pressing (HIP) of mechanically alloyed nanocrystalline powders. An ultra-high pressure (1 GPa) HIP equipment was used in an effort to consolidate the mechanically alloyed powders into fully dense compacts while retaining the nanocrystalline microstructure. The densification of powders was found to depend largely on the HIP temperature. Fully dense compacts with a grain size of about 200 nm were obtained after HIP treatment at 1073 K. Mechanical properties of the compacted materials at room and elevated temperatures were determined by hardness and compression tests. Ti addition significantly increased the hardness and room temperature yield strength, but this increase was accompanied by a reduction in ductility. The yield strength decreased monotonically with increasing temperature with no positive temperature dependence observed. The high temperature deformation processes were investigated by examining the strain rate sensitivity and the deformation microstructure. Compared with the binary Fe3Al, the Ti-added alloy exhibited lower strength but better deformability at temperatures above 1073 K.