Precipitation Behavior of σ-FeCr Phases in Hastelloy C-2000 Superalloy Under Plastic Deformation and Aging Treatment

Precipitation behavior and structural feature of the σ-FeCr phase in Hastelloy C-2000 alloy under plastic deformation and aging treatment are investigated using scanning electron microscopy, transmission electron microscope, and x-ray diffraction. The plate-shaped σ-FeCr phase can precipitate in the alloy by plastic deformation and aging treatment because of the increase of both defect density and heterogeneity of alloying elements. This phase is distributed along the interface between matrix and deformation twins. The appearance of unidirectional faults on surface of the σ-FeCr phase indicates that it may be a metastable-phase. Because of the precipitation of the brittle σ-FeCr phase and the increase of defects’ density such as dislocation and deformation twins in the matrix, mechanical properties of the alloy are improved remarkably.