Ferritic Fe–Al–Ni–Cr alloys with coherent precipitates for high-temperature applications

Strengthening by a homogeneous distribution of a second phase is a concept that is widely employed in high-temperature materials. It is shown that suitable microstructures can be obtained in the Fe–Al–Ni–Cr system with ordered (Ni, Fe)Al precipitates in a ferritic matrix. These precipitates lead to higher levels of yield strength at elevated temperatures than conventional iron-base high-temperature alloys. The results show that the investigated materials exhibit the highest yield strength after solution heat treatment and lower values after aging, indicating precipitation of fine particles during air cooling. The decrease of yield strength in the latter case was more pronounced for alloys with a high precipitate content than for leaner alloys.