Nano-sized precipitation arising from partial substitution of Mo for Cr in FeCo-2V-0.5Cr alloy and its role in creep resistance

This work presents the formation of numerous nano-sized and rod-like precipitates in FeCo-2V-0.5Cr alloy due to a partial substitution of Mo for Cr and its role in the enhancement of creep resistance. The nano-sized precipitates feature disordered body-centered cubic structure with high stability during the creep process at 600 °C, resulting in a great reduction in minimum creep rate by an order of magnitude. While for the rod-like precipitates, they are characterized by face-centered cubic (FCC) structure. From high resolution transmission electron microscopy analysis, it can be suggested that the Mo partial substitution helps to stabilize the FCC precipitate due to the larger Mo atomic radium with respect to Cr which can suppress the FCC to hexagonal close packed phase transformation occurring in Mo-free FeCo-2V-0.5Cr alloy.