The effect of loading mode changes during the sintering process on the mechanical properties of FeAl intermetallic sinters

In this paper, we present the results of a uniaxial compression test and the Charpy impact test of FeAl intermetallic sinters. The FeAl intermetallics were fabricated by a three-stage process from iron and aluminum elemental powders which were mixed in a 50/50 at.% stoichiometric ratio. The mixed powders were then uniaxially cold pressed at RT, preliminarily sintered at 900 °C under pressure and finally homogenized at 1150 °C. The proposed process resulted in the formation of a fine-grained FeAl intermetallic matrix with Al2O3 oxides. The second stage of this process, preliminary sintering, was run with either static or cyclically variable loads. The change of the load mode from static to cyclical resulted in changes to the morphology and location of Al2O3 oxides and also an increase in compression strength (Rc), ductility (A) and impact resistance (KC) of the sintered materials. Moreover, the three-point bending test was conducted for sinters obtained with cyclic load. Additionally, the acoustic emission effect was used to estimate the critical stress intensity factor and its dependence on crack length and the change of crack growth velocity.