Microstructural evolutions and fracture behaviors of a newly developed nickel-base superalloy during creep deformation

Low cycle fatigue behavior and microstructural evolution of nickel-based superalloy M951G at elevated temperatures

“…On the other hand, as it is commonly known that the casting micropores are mainly distributed at the final solidification stage of the alloy, such as grain boundaries and interdendritic regions. In the present study, the statistical grain size of M951G alloy is about 3.273 mm (the standard deviation is 1.435 mm), which means the grain boundary content is very low [7]. Therefore, most of casting micropores are located in the interdendritic regions, only a small amont along the grain boundaries.…”

“…7e) become the crack initiation sources. Additionally, for the experimental alloy in present work, majority of eutectics and carbides are distributed in interdendritic regions, and the mean size of interdendritic carbides is much larger than that along the grain boundaries [7]. Therefore, microcracks have more probabilities to initiate within the grain interior, and finally promote the formation of transgranular cracks.…”

“…3e). The micropores on the final rupture region are considered to be formed by the coalescence of casting pores via the aggregation of vacancies [7,58,59]. Two crack nucleation mechanisms are observed on the fracture surfaces: Majority of cracks form at the oxides (identified as oxidized carbides by EDS in Section 3.2.3) on the specimen surface (Fig.…”

“…As unique high temperature materials used in the aircraft engines and industry gas turbine engines, nickel-based superalloys consist of plenty of ordered γ′ precipitates with L12 structure coherently embedded in γ matrix with fcc (face-centered cubic) structure, thus displaying excellent resistance to mechanical and chemical degradation at temperatures close to their melting points [1][2][3][4][5][6][7].…”

“…Therefore, it is necessary to study the influences of temperature and stress on the mechanical properties of superalloys. In the past several decades, much work has been done in this field, such as tensile [8][9][10][11][12][13][14] and creep deformations [5,7,[15][16][17][18][19][20] of superalloys. However, in practical application, the blades are subjected to cyclic thermal stress resulting from start-up and shutdown procedures [21,22].…”