Evolution of the short range order parameter for the transformation A2„±D03 in Fe75Ge25

A.F. CABRERA, F.H. SÁNCHEZ, L. MENDOZA ZÉLIS

HYPERFINE INTERACTIONS

SPRINGER

Año: 1999 vol. 4 p. 137 - 140

0304-3843

In this contribution order-disorder transformation results in Fe75Ge25 alloys, are presented. The disordered (A2) Fe75Ge25 [1] can be ordered in the D03 structure by thermal treating at 400 ¢XC for 4 hs [2]. The Mössbauer study of the system treated at different temperatures between 100 and 400 ¢XC allowed the investigation of the local atomic configuration around the Fe probes. It was found that the hyperfine field and isomer shift values depend essentially on the number of nearest neighbours. The short range order parameter, obtained by analysis of the Mössbauer spectra, undergoes an important increment at 200 ¢XC. This analysis indicated that the transformation occurs by gradual ordering into the D03 structure. The XRD results, instead, show that long range order into the D03 structure begins at about 325 ¢XC.