Maps of Fe–Al phases formation kinetics parameters during isothermal sintering

The influence of technological parameters (compaction pressure and sintering temperature) on Fe–Al phase formation was investigated. The kinetics of phase transformation preceding and during an SHS reaction was studied in isothermal conditions by DSC using the JMA (Johnson–Mehl–Avrami) model. This model allowed us to determine basic kinetic parameters, including the Avrami exponent, which characterises the rate and manner of particular phase nucleation. The activation energy (Ea) of particular phase formation was determined by the Kissinger method. XRD analysis and SEM observations of sintered material showed that not only Fe2Al5 phase and low-aluminium solid solution in iron but also aluminium-rich FeAl2 and FeAl3 phases are formed during the sintering of an FeAl50 elementary powder mixture in isothermal conditions with an SHS reaction. The above conclusions were confirmed by iron-based solid solution lattice parameter studies and microhardness measurements.

► The sintering temperature and compaction pressure have a strong influence on the sinters structure. ► The measurements confirmed the presence of the high-aluminium phases from Fe–Al equilibrium system in tested sinters. ► The kinetics of Fe–Al phase formation can be described by Johnson–Mehl–Avrami modelling.