Anisotropy of stress rupture properties of a Ni base single crystal superalloy at two temperatures

Constitutive modeling of creep behavior in single crystal superalloys: Effects of rafting at high temperatures

“…However, the loading direction is not exactly [111] due to misorientation and the internal stress state has a strong dependence on the local microstructure. Therefore, the rafting direction in [111] creep will be highly localized [8,9].…”

“…Studies reported by Jacome [6] and Han [7] showed that a single crystal superalloy under [011] tensile creep exhibited a plate-like structure at an angle of 45°to the loading axis. Other researchers [8,9] found that rafting did not occur or highly localized in [111]-oriented creep tests. Apart from uniaxial creep tests, Kamaraj and Serin [10,11] studied the rafting under the multiaxial stress state with double shear tests in [001] and [110] orientations.…”

Anisotropic Stress Rupture Properties of a 3rd-Generation Nickel-Based Single-Crystal Superalloy at 1100 °C/150 MPa

“…At temperature range of 750-871 °C, the creep behaviors for the specimens with [001], [011] and [111] orientations have been fully investigated, which are thought to be highly anisotropic. Many studies [6,[8][9][10][11] indicated that the creep anisotropy at this temperature range was mainly attributed to the activation of different <112> {111} and <110> {111} slip systems for different oriented specimens. With the development of advanced aircraft engines, new generations of SX nickel-based superalloys operate at higher temperatures over 1000 °C.…”

“…High-temperature deformation of SX superalloys is dominated by several prominent features, such as directional coarsening of γʹ precipitates [12][13][14], formation of dislocation networks at γ/γʹ interface [15,16] and γʹ phase cutting by a<110> or a<100> superdislocations [17][18][19][20][21], but most of the studies focus on the deformation in [001]-oriented SX superalloys. The creep deformations of [011] and [111] specimens have so far received sporadic attention [9][10][11][22][23][24][25][26][27]. Sass et al [9,10] showed that the rafted γʹ phase reduced the creep anisotropy of [001]-and [011]-oriented CMSX-4 alloys at 980 °C.…”

“…No directional coarsening of γʹ phase was observed in [111] specimens, which resulted in the poorest life of [111] specimens. Liu et al [11] thought that variation of rafts could strengthen the [111] specimens and N-type rafts might lead to shorter life of [001] specimens during creep at 1010 °C/248 MPa. However, Su et al [22] confirmed that N-type rafted γʹ phase in [001] specimens could effectively hinder the movement of matrix dislocations and result in the strain hardening.…”