Effects of Co content on tensile properties and deformation behaviors of Ni-based disk superalloys at different temperatures

Tensile properties of three Ni-based disk superalloys with 5 wt.%, 15 wt.% and 23 wt.% Co contents were investigated from room temperature (RT) to 725 degrees C with a constant strain rate of 3 x 10(-4) s(-1). It is found that addition of Co enhances the yield strength and the strain hardening capacity of the alloy in the studied temperature regime. It is due to the following two reasons: i.e. the interactions between a large volume fraction of fine secondary and tertiary gamma' precipitates with the dislocations in slip bands at lower temperatures and the formation of deformation microtwins at higher temperatures. However, the formation of deformation microtwins in the high Co-containing content alloy sharply decreases the ductility at higher temperatures. (C) 2015 Elsevier Ltd. All rights reserved.