Thermal point defects in FeAl, CoGa and NiGa intermetallic compounds

The annealing of thermal point defects in quenched intermetallic compounds FeAl, CoGa and NiGa with B2 structure has been investigated using magnetic and calorimetric techniques. In FeAl compound, the magnetic susceptibility x(T) measurements performed during an isochronal annealing after a quench lead to the determination of the eliminated thermal defect concentrations from fitting the experimental x(T) curves by Curie-Weiss law. The vacancy concentrations coupled to annealing heat, measured by differential scanning calorimetry, allow us to obtain the vacancy formation enthalpy in FeAl. For the three studied intermetallic compounds, the activation enthalpies, associated to the elimination of thermal point defects were determined and discussed taking into account the formation of vacancy clusters in FeAl and CoGa.