Program package CONFIT enables a complex processing of 57 Fe and 119m Sn Mössbauer spectra. The mouse drag-and-drop technique is used to set up the background and parameters of the individual spectral components according to the structural model supposed. An original method has been applied: a nonlinear least-squares procedure with the Fast Fourier Transform (FFT) technique. A combination with improved matrix formalism can create various physical models to analyze the measured experimental data in a proper way. The hyperfine field distribution(s) and also quadrupole splitting distribution(s) with Gaussian profile can be applied, besides discrete components. The finite sample thickness can be included in terms of transmission integral and a dependence of the spectral line-width on its position with respect to the spectrum center is described by an additional parameter. This fitting procedure is suitable for Mössbauer spectra taken in the transmission and in the back-scattering geometry (including g-ray and conversion electrons) and it can be successfully applied for analyzing the emission Mössbauer spectra. The transmission Mössbauer spectra yield information concerning the bulk microstructure, the backscattering geometry is used for surface studies and the emission Mössbauer spectra yield information from grain boundaries or interface regions. The CONFIT is user friendly, fast and applicable for complicated Mössbauer spectra.

The formation of thermal vacancies in the intermetallic compound Fe76 3A1$3 7 was investigated between 20 and 1060'C by positron-lifetime measurements. The positron lifetime~&=112 ps at 20'C indicates that no structural vacancies can be detected. The increase of the mean positron lifetime 7 due to thermal vacancy formation starts at relatively low temperatures (T3 =475'C). The fit of a simple two-state trapping model to the temperature variation of~yields an effective vacancy formation enthalpy H =1.1820.04 eV, which suggests a thermal vacancy concentration at the melting temperature of several atomic percent which is much higher than in pure metals and similar to that found in some intermetallic compounds with a B2 structure. From a comparison with selfdiffusion results, a vacancy migration enthalpy of H =1.4-1.6 eV is deduced. The phase transitions in the present a11oy are discussed in terms of vacancy formation and migration.

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