"Estimation of the sizes of coherent scattering areas in alloys based on neutron diffraction data"
Erzhanov Bekarys (FLNP JINR, KFU Institute of Physics, Kazan, Russia)
The results of the analysis of the diffraction spectra of the Fe74Al26 alloy, measured on a high-resolution neutron diffractometer, aimed at determining the size distribution of structurally ordered clusters dispersively embedded in a structurally disordered alloy matrix are discussed in the report. For this purpose, generalization of the Scherrer method based on the analysis of diffraction peak profiles, determination of peak widths at heights of 1/5 and 4/5 from the maximum and the assumption that the gamma distribution is valid for cluster sizes (Pelaszek's method) has been used.
The results obtained by the Scherrer, Williamson-Hall and Pelasek methods are compared and their good agreement with each other is shown. An algorithm for calculating a physically more reasonable logarithmically normal distribution is proposed. The experimental data were obtained on a time-of-flight neutron diffractometer, therefore they were analysed for two variants of the scanning variable: in the crystalline (d-scale) and inverse (H-scale) spaces and estimates of possible systematic errors were obtained.