Second Phases in Fe-25Cr-35Ni Based Super Alloy

The second phases and their distribution in Fe-25Cr-35Ni based super alloy were investigated through optical microscope, scanning electron microscope and energy diffraction spectrum. The results show that there are mainly three kinds of second phases in Fe-25Cr-35Ni based super alloy and they are Nb-rich phase, nitride phase and carbide phase. The Nb-rich phases mainly distribute along the grain ground, and there is chemical compositions difference between the Nb-rich phases. The nitride phases mainly are TiN and generally intergrow with the Nb-rich phases, and their distributing relates to the segregation of nitride. The carbide phases amount is more and they distribute in the grains, grain boundaries, twins and twin boundaries. And the carbide phases could be dissolved into the base metal after high temperature solution treatment.