Creep-induced planar defects in L12-containing Co- and CoNi-base single-crystal superalloys

Effect of doping Mg on the microstructure and mechanical behaviours of a novel Co-9Al-4.5W-4.5Mo-2Ta-0.02B alloy at room- and high-temperatures

“…This mechanism is the same as that in the g 0 -Ni 3 Al compound [20,21]. TEM analysis confirmed that slip of ordinary a/2〈1 0 1〉{1 1 1} dislocations through the g-Co SS matrix, rafting of the g 0 precipitates perpendicular to the external compressive stress axis [22] and glide of the superlattice intrinsic and extrinsic stacking faults in the g 0 precipitates [23,24] are the main creep mechanisms of the Co-Al-W base alloys.…”

L12-Strengthened Cobalt-Base Superalloys

“…At elevated temperatures (up to the γ -solvus temperature), extensive shearing of the γ phase in Co-base alloys has been observed. The shearing process results in the formation of SISFs and SESFs (superlattice extrinsic stacking faults) by a process that involves the reaction of two unit matrix dislocations at the γ-γ interface that form a/3<112> super-Shockley partial dislocations that shear the precipitate while leaving a second a/6<112> partial dislocation at the precipitatematrix interface (50,57,62). After creep deformation at 900 • C, high densities of faults are observed in the precipitates (Figure 13a).…”

“…In Co-Ni-base alloys, another unusual mode of shearing of the γ phase becomes prominent as the Ni content increases (62). During high-temperature creep, shearing of precipitates occurs by the motion of unit a/2<110> dislocations that leave behind APBs in the ordered precipitates (Figure 13b).…”

The microstructure and hardness of Ni-Co-Al-Ti-Cr quinary alloys

“…In the ten years since this discovery, considerable work has been performed to gain an enhanced understanding of the behaviour of these materials and develop commercially viable alloys. This research has included studies of the phase equlibria and the effect of alloying [13][14][15][16][17][18][19][20][21][22][23][24][25][26][27], evaluation of their deformation behaviour [22,[28][29][30][31][32][33][34][35][36][37][38][39][40][41], and assessment of their environmental resistance [42][43][44]. However, despite exhibiting several beneficial attributes, further development is still required before any of these alloys can compete with existing Ni-based superalloys.…”