Résumé: The local environment issued from the phase decomposition in the Fe:30.8Cr:12.2Co alloy has been investigated by 57Fe Mossbauer spectrometry as a function of the ageing time and temperatures. In order to enable a precise determination of the different configurations, the analysis of Mossbauer spectra is improved using several different fitting models. It has been concluded that the phase decomposition in the Fe-30.8Cr-12.2Co alloy is spinodal and gives rise to the formation of a paramagnetic ([alpha]′) phase and a magnetic ([alpha]) phase, with relative areas of ~5% and ~95%, respectively. The magnetic phase results from three main domains: an Fe:rich, a Cr:rich and a Co:rich with relative proportions of 9, 42 and 44%, respectively. The Cr content in the Fe:rich ([alpha]) phase is about 9 at.% Cr while that of the Cr:rich ([alpha]′) phase is ranged between 71 and 80 at.% as a function of time and ageing temperature, which can be attributed to the kinetics of the phase decomposition. The ([alpha]′) volume fraction estimated at about 28% is consistent with an isotropic decomposition where both ([alpha]) and ([alpha]′) phases are strongly interconnected.

Langue: Anglais