Etude comparative de l'alliage Fe-30 % at. Al obtenu par fusion conventionnelle et hypertrempe

Abstract

This work concerns the Fe-30 at. % Al alloy prepared by two different methods, the conventional fusion and the rapid solidification and its aim is the study of the solidification speed effect, the ageing time and the annealing temperature on the order-disorder transformation. Several experimental methods have been used to follow the various structural evolutions resulting from the thermal processing: optical microscopy, X-rays diffraction, differential scanning calorimetric analysis, dilatometric analysis and microhardness measurements. The synthesis and the analysis of many and interesting experimental results obtained by these various techniques have allowed us to notice that the transition B2 -» a is shifted towards low temperatures (857°C) for the ribbons (prepared by rapid solidification) which present a finer microstructure and a higher microhardness. Moreover the structural state is identical for the two samples after ageing at different temperatures. Finally, the differential calorimetric analysis and the dilatometry, seldom used in this kind of study, constitute very significant and complementary methods for this type of transformations.