Study On The Mechanical Properties Of The Third Generation Nickel-based Single Crystal Superalloy In The Medium Temperature Region

Nowadays Ni-based single crystal superalloy has become a key material for the manufacture of modern aero-turbine engine blades because of its excellent comprehensive high-temperature properties.In this paper,the microstructure evolution during in-situ tensile test at medium temperaturethe of a third-generation nickel-based single crystal superalloy under pulling and heating conditions has been studied by means of environmental scanning electron microscopy(ESEM).Before the specific tensile specimens are prepared,The master alloy has undergone exactly the appropriate solid solution treatment and aging strengthening.At the temperature of 750?,the tensile experimental results indicate that the sliding system which consists of close-packed plane of atoms of {111} and strong direction of <110> is started first in the tensile process,in addition,other sliding systems have been started with the increase of plastic deformation.Moreover,tensile specimens produce dislocation movements in the process of stretching,the dislocation glide mechanism is cutting through the ?? strengthening phase at that temperature,which contributes to the intermediate-temperature hardening behavior in the alloy.The fracture morphology's microstructure analysis of the tensile specimen at 750? indicates that there are obvious dimples on the surface of the fracture,which shows as microporous aggregate fracture.The fracture of the alloy at that temperature is mainly ductile fracture.The energy dispersive spectrum(EDS)analysis of tensile specimens under the transmission electron microscope(TEM)indicates that Co,Cr,W,Mo,Re alloy elements are mainly concentrated in the matrix.Meanwhile,Al,Ti and Ta are the main components of the ?? strengthening phase.