L12-strengthened multicomponent Co-Al-Nb-based alloys with high strength and matrix-confined stacking-fault-mediated plasticity

Anomalous Work Hardening Behavior of a Single Crystalline Co-Base Superalloy

“…While the yield strength of the ternary Co-Al-W drops sharply above the peak temperature as single matrix dislocations are able to bypass the precipitates in combination with a partial dissolution of the γ precipitates, the addition of Ta leads to a less pronounced decrease in the yield strength, which is associated with extensive stacking fault (SF) formation inside the γ precipitates [3]. In subsequent studies, this effect was confirmed as the transition to extensive stacking fault shearing with increasing temperatures sometimes even led to the maintenance or an increase in the yield strength of some Co-base and CoNi-base superalloys [10][11][12]. Furthermore, extensive stacking fault formation and frequent interactions between these planar defects also cause high work hardening rates [3,11] and this is also assumed to cause strengthening during creep [13][14][15][16][17][18].…”