Magnetic and calorimetric study of point defects in FeAl intermetallic compound

The behaviour of point defects has been investigated in quenched B2-FeAl in termetallic compounds by using magnetic susceptibility measurements chi(T) and differential scanning calorimetry (DSC). During an isochronal annealing , the observed step in magnetic susceptibility at about 410 degrees C refle cts the migration of iron antistructure atoms, frozen by the quenching proc ess, to their own sites. Several thermal phenomena have been detected by me ans of DSC measurements. The principal peak, attributed to the migration an d elimination of iron antistructure atoms via vacancy mechanism, depends on the quenching temperature T-q: for T-q = 1000 degrees C, the annealing-out temperature range is lower by about 150 degrees C than for T-q = 800 degre es C. The concentration of eliminated vacancies, during this stage, has bee n determined from fitting the experimental chi(T) curves by the Curie-Weiss law: it was found to be 1.76 x 10(-2) for the equiatomic composition and 1 .73 x 10(-2) for the Fe49Al51 compound. The annealing kinetics study allows us to determine the migration enthalpy of 1.95 eV taking into account the formation of vacancy clusters. (C) 2000 Elsevier Science S.A. All rights re served.