Abstract
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(1(1)1)dominant slip plane were consistent with the in situ SEM observations.
基金项目
National Natural Science Foundation of China(Grant Nos.52205139)
National Natural Science Foundation of China(12172021)
National Natural Science Foundation of China(52105156)
National Science and Technology Major Project of China(2019-Ⅳ-0017-0085)
Science Center for Gas Turbine Project(P2022-Ⅲ-003-002)
Academic Excellence Foundation of BUAA for PhD Students()
万方数据