Mechanical behavior of coated T91 steel in contact with lead-bismuth liquid alloy at 300°C

Different coatings, deposited by pack cementation process, were developed to protect the T91 steel against dissolution by Lead Bismuth Eutectic (LBE): iron aluminide, iron boride and an iron solid solution enriched in chromium and covered by carbide. The mechanical behavior of the T91 steel with the different coatings is studied in air and in LBE at 300 °C by the use of the Small Punch Test (SPT). Though the coatings are brittle, they do not affect the mechanical strength of the substrate in air, except the iron boride one. In LBE, the most critical situation is found when fracture of the interface between the T91 steel and the coating occurs. Then, the coating provides the set of conditions to trigger liquid metal accelerated damage.