Enhanced strength at intermediate temperatures in a Ni-base disk superalloy with high Co addition

Characterization of hot compression behavior of a new HIPed nickel-based P/M superalloy using processing maps

“…Previous results [25][26][27] showed the evidence that increasing Co content might improve phase stability, lower the gamma prime solvus, and reduce the quenching residual stress. Recently, a series of new-developed nickel-based superalloys containing up to 30% Co demonstrated an excellent combination of high-temperature strength [28,29], creep resistance [30], low cycle fatigue, and fatigue crack growth rate [31]. Meanwhile, the addition of hafnium (Hf) was favorable for improving grain-boundary stability [2], as well as promoting the formation of a cellular γ′ precipitation [32].…”

The synchronous improvement of strength and plasticity (SISP) in new Ni-Co based disc superalloys by controling stacking fault energy

“…Generally, increasing Co content can enhance the stability of precipitates and lower the γ′ solvus temperature, which widens the processing window and reduces the thermal stresses induced by controlled cooling and quenching in superalloys 31 . It has been reported that high Co addition up to 30% made no difference to the phase constituent, but the size of secondary γ′ will firstly decrease with increasing Co content, and then remain unchanged with further addition of Co above 25% 39 . Since higher Co content will result in lower γ′ solvus temperature in alloys, in this case secondary γ′ will form at lower cooling temperature and have less time to grow up.…”

Temperature Effects on the Deformation Mechanisms in a Ni-Co-Based Superalloys

“…The intermediate and high-temperature deformation mechanisms have been extensively investigated in the past decades [10][11][12][13][14][15][16][17]. The research results of Yuan et al [18] show that the addition of the Co element reduces the stacking fault (SF) energy of the Ni-based superalloy and influences its deformation mechanism. The dominant deformation mechanism of superalloys is that a pair of dislocations shear γ precipitates at low temperatures, while SF is formed by the movement of partial dislocations at intermediate temperatures.…”