Effect Of Orientation On Mechanical Properties Of A Ru-Nickel-Based Single Crystal Superalloy

Nickel-based single crystal superalloys are widely applied as the turbine blade high-temperature materials for the four-hot end components in the aircraft engines.With the continuous development of aviation aircraft,higher performance requirements have been put forward for aircraft-engine turbine blades.Turbine blades are one of the four hot-end components of aircraft engines,and they also have extremely high requirements for their performance.The main stress direction of the turbine blades is along its[001]orientation.Not only by the centrifugal stress,but also by the thermal and cyclic stress,which causes the turbine blade to be locally stressed in all directions.In addition,during the service life of the turbine blade,its lattice rotates,causing the main force direction of the turbine blade to deviate from the[001]orientation.Meanwhile,the nickel-based single crystal superalloy contains 60%-70%of the ordered second phase,which results in anisotropy of mechanical properties of the nickel-based single crystal superalloy.However,there are very limited researches on the effect of orientation on the tensile properties and stress-rupture properties of the fourth-generation single crystal superalloys.Therefore,in this paper,[001],[011]and[111]superalloys were prepared using a nickel-based single crystal superalloy containing Ru element as experimental materials.The effect of orientation on tensile properties and stress-rupture properties of a nickel-based single crystal superalloy containing Ru element were investigated.Based on this background,in this paper,the fourth generation nickel-based single crystal superalloys containing Ru element with[001],[011]and[111]orientations were used as experimental materials.The tensile behavior and stress-rupture behavior of the three oriented superalloys and the corresponding microscopic deformation mechanism and the effect of orientation on the mechanical properties such as tensile and stress-rupture were studied by electron backscattered diffraction(EBSD),scanning electron microscopy(SEM)and transmission electron microscopy(TEM)and X-ray(XRD).The main contents and results of this paper are as follows:(1)By observing the as-cast dendritic patterns and heat-treated scanning microstructures of the[001],[O11?,and[111]samples,the results show that the as-cast dendritic patterns of the[001]and[011]samples were "+",while the as-cast dendrite pattern of the[111]sample with orientation was equilateral triangle.The y' phase of the[001]sample appears as a cube;the ?' phase of the[011]sample appears as a rectangle;the ?' phase of the[111]sample appears as an equilateral triangle.The comparison found that orientation affects the as-cast microstructure and heat-treated ?/?' two-phase morphology of single crystal superalloys.(2)The effect of orientation on the tensile properties of single crystal superalloys containing Ru were studied by the tensile experiments of[001],[011]and[111]samples,and the microstructure of the samples was studied.Observation and analysis of the deformation mechanism show that the tensile properties of the[111]samples were the best at room temperature,760?,and 1100?,and the tensile properties of the[011]samples were the worst.The plasticity of the[011]sample was the best at room temperature and 1100?,and the plasticity of the[111]oriented sample was the best at 760?.It was found that the tensile properties of the sample were affected by its Schmid factor and the amount of effective slip coefficient.(3)The effect of orientation on the stress-rupture properties of nickel-based single crystal superalloys containing Ru were studied by the stress-rupture experiments of[001],[011]and[111]samples,and the microstructure observation and the analysis of the deformation mechanism of the samples showed that the[111]specimen has the best stress-rupture property,and the[011]specimen has the worst stress-rupture property under midium temperature and high stress.The[001]specimen has the best stress-rupture property under high temperature and low stress;the[111]specimen has the s worst stress-rupture property under 1100?/165 MPa;and[011]samples have the worst stress-rupture property at 1140?/137 MPa.It is found through research that the stress-rupture properties of the specimens with[001],[011]and[111]orientations are affected by their deformation mechanism.