EFFECTS OF HEAT-TREATMENT AND COOLING RATE ON MICROSTRUCTURAL AND MECHANICAL CHARACTERISTICS OF ALUMINIDE COATINGS ON MANET STEEL

R&D studies concerning Pb-17Li blankets for DEMO suggest the use of co atings either as tritium permeation barriers for the water cooled blan ket or as electrical insulators for the self cooled blanket, The produ ction of coatings resistant to the thermal and mechanical stresses typ ical of the blanket operating conditions is the target. The present wo rk describes the results of an experimental programme aimed at evaluat ing the effects of heat treatment and cooling rate on the microstructu ral and mechanical characteristics of aluminide coatings deposited on MANET steel (DIN 1.4914) by the hot-dipping process. The temperature o f the post-deposition heat treatment that allows obtaining structures like FeAl and alpha-Fe(Al), instead of the mon brittle FexAly intermet allics, has been identified. The coatings have been characterized by o ptical metallography, microhardness measurements, scanning electron mi croscopy (SEM), energy dispersive X-ray analysis (EDS) and X-ray diffr action on the surface.