|About this Abstract
||2017 TMS Annual Meeting & Exhibition
||Energy Materials 2017: Materials for Gas Turbines
||Revisiting the Sources of Creep Dislocations in Ni-base, Single Crystal Superalloys
||Farangis Ram, Zhuangming Li, Zailing Zhu, Masood Hafez Haghighat, Stefan Zaefferer, Dierk Raabe, Roger Reed
|On-Site Speaker (Planned)
The origin of creep dislocations in Ni-base, single-crystal superalloys at intermediate stress and temperature regimes is revisited. High angular resolution Electron backscatter diffraction (HR-EBSD), electron channeling contrast imaging (ECCI), and discrete dislocation dynamics modeling (DDD) were employed in this study. We found that grown-in, low-angle boundaries are only a minor source of creep dislocations. They only account for those creep dislocations that are in their close vicinity−not farther that 10 μm. Major sources of creep dislocations are isolated, individual dislocations in the uncrept material. They are homogenously spread in small quantities (1011 m/m3) far from subgrain boundaries before creep begins and are activated after activation of dislocations in subgrain boundaries. Once activated, they emit avalanches of creep dislocation into boundary-free regions and increase the dislocation density by two orders of magnitude.
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