Aging behavior of Fe-30 Ni-1.0 Nb-0.1 C alloy

A study has been made of the precipitation reaction in Fe-30 wt% Ni-1.0 wt% Nb-0.1 wt% C alloy. The as-quenched structure of this alloy consists of austenite and martensite. On aging at 700° and 800°C the main precipitation reaction results in the formation of NbC. The precipitation of NbC occurs on dislocations, in austenite as well as in martensite, and on the martensitic interfaces and results in a considerable increase in the hardness of the alloy. Beside NbC small amounts of M6C were also detected and in the specimens overaged at 800°C NbC, M6C and Fe2Nb precipitates were identified.