Fe–Al Phase Formation Studied by Internal Friction during Heating Process

We systematically investigate the internal friction properties of a Fe–(43 at.%)Al powder mixture compact during the heating process with the expectation to understand the phase formation and transition process. Three internal friction peaks are successively observed during the heating process from room temperature to 750^\circ\!C, but almost completely disappear in the subsequent cooling process. Three internal friction peaks exhibit obvious measuring frequency dependence, which increases with decreasing the frequency. The first internal friction peak originates from the micro-sliding of weak bonding interface between Al particles corresponding to a recrystallization process of deformed Al particles. The second internal friction peak is attributed to a phase formation process associated with the formation of the intermediate phase Fe_2Al_5. The third internal friction peak is considered to result from the formation of the FeAl intermetallic compound owing to the reaction of Fe_2Al_5 and residual Fe initiated by a dramatic thermal explosion reaction.