Microstructure and dislocation structure evolution during creep life of Ni-based single crystal superalloys
来源期刊：JOURNAL OF MATERIALS SCIENCE TECHNOLOG2020年第10期
论文作者：Hao Yua Wei Xu Sybrand van der Zwaag
文章页码：207 - 214
摘 要：The high performance of Ni single crystal superalloys during high temperature low stress creep service, is intrinsically determined by the combined effects of microstructural evolution and the dislocation behaviour. In the field of the evolution of dislocation network, two main recovery mechanism based on dislocation migration dominate the process. One is superdislocations shearing into γ’ rafts through a two-superpartials-assisted approach. Another is the compact dislocations migrating along γ/γ’ interface. These two mechanisms are similarly climb-rate-controlled process. In this work, a model for the minimum creep rate based on thermodynamic and kinetic calculations and using an existing detailed dislocation dynamics model has been built by taking the dislocation migration behaviours as well as the rafted microstructure into consideration, which can well reproduce the（[100] tensile） creep properties of existing Ni superalloy grades, without the need to make the dislocation parameter values composition dependent.
Hao Yua1，Wei Xu1,2，Sybrand van der Zwaag1
1. Novel Aerospace Materials Group, Faculty of Aerospace Engineering, Delft University of Technology2. State Key Laboratory of Rolling and Automation, Northeastern University
摘 要：The high performance of Ni single crystal superalloys during high temperature low stress creep service, is intrinsically determined by the combined effects of microstructural evolution and the dislocation behaviour. In the field of the evolution of dislocation network, two main recovery mechanism based on dislocation migration dominate the process. One is superdislocations shearing into γ’ rafts through a two-superpartials-assisted approach. Another is the compact dislocations migrating along γ/γ’ interface. These two mechanisms are similarly climb-rate-controlled process. In this work, a model for the minimum creep rate based on thermodynamic and kinetic calculations and using an existing detailed dislocation dynamics model has been built by taking the dislocation migration behaviours as well as the rafted microstructure into consideration, which can well reproduce the（[100] tensile） creep properties of existing Ni superalloy grades, without the need to make the dislocation parameter values composition dependent.
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