Effects of rafting on the meso deformation and fracture behaviour of a Ni-based single crystal superalloy at room temperature: In-situ observation and simulation  

作　　者：TAN Long YANG XiaoGuang SHI DuoQi FAN YongSheng SHI Yi 

机构地区：[1]School of Energy and Power Engineering,Beihang University,Beijing 102206,China [2]Research Institute of Aero-Engine,Beihang University,Beijing 102206,China [3]National Key Laboratory of Science and Technology on Aero-Engine Aero-Thermodynamics,Beihang University,Beijing 102206,China [4]School of Materials Science&Engineering,Shanghai Jiao Tong University,Shanghai 200240,China

出　　处：《Science China(Technological Sciences)》2024年第7期2133-2146,共14页中国科学（技术科学英文版）

基　　金：supported by the National Natural Science Foundation of China (Grant Nos. 52205139, 12172021, and 52105156);the National Science and Technology Major Project of China (Grant No. 2019-IV-00170085);the Science Center for Gas Turbine Project (Grant No. P2022-III003-002);the Academic Excellence Foundation of BUAA for PhD Students。

摘　　要：Microstructural rafting of Ni-based single-crystal(SC) superalloys is inevitable at elevated temperatures during long-term service with mechanical loading, which significantly affects the mechanical behaviour of the material. In this study, the effects of rafting on the mesodeformation and fracture behaviour of a Ni-based SC superalloy under cyclic and tensile loads were investigated using in situ scanning electron microscopy(SEM), digital image correlation(DIC), and crystal plasticity finite element method(CP-FEM) simulations. The results indicated that the tensile strength decreased significantly in the rafted specimens. In the cyclic tests, both the virgin and rafted specimens showed an increase in the maximum shear strain with cycle number. The interaction of cross-slip bands was captured by in situ SEM-DIC around the micro-notch of the virgin specimens during the tensile test, while a more homogeneous local deformation field was observed in the rafting specimens. In addition,the fracture behaviour was strongly influenced by the rafting morphology. The crack exhibited instantaneous and long-range fracture features along the octahedral plane as it propagated in the rafting specimen, whereas it deflected over a short distance between the crystallographic planes at an early stage in the virgin specimen, which is consistent with the CP-FEM results.Furthermore, the CP-FEM results for the crack initiation direction on(111) dominant slip plane were consistent with the in situ SEM observations.

关 键 词：in-situ SEM-DIC Ni-based SC superalloys microstructural rafting deformation crack path CP-FEM 

分 类 号：TG132.3[一般工业技术—材料科学与工程]