Abstract
In order to investigate the anisotropic micromechanical properties of single-crystal nickel-based superalloy DD99 of four crystallographic orientations, (001), (215), (405), and (605), microindentation test (MIT) was conducted with different loads and loading velocities by a sharp Berkovich indenter. Some material parameters reflecting the micromechanical behavior of DD99, such as microhardnessH, Young’s modulusE, yield stressσy, strain hardening componentn, and tensile strengthσb, can be obtained from load-displacement relations.HandEof four different crystal planes evidently decrease with the increase ofh. The reduction ofHis due to dislocation hardening whileEis related to interplanar spacing and crystal variable.σyof (215) is the largest among four crystal planes, followed by (605), and (001) has the lowest value.nof (215) is the lowest, followed by (605), and that of (001) is the largest. Subsequently, a simplified elastic-plastic material model was employed for 3D microindentation simulation of DD99 with various crystal orientations. The simulation results agreed well with experimental, which confirmed the accuracy of the simplified material model.
Highlights
In recent years, single-crystal nickel-based superalloys are widely used as blade of modern gas turbine aeroengines, as they significantly raise the operation temperature and efficiency due to excellent mechanical properties in service [1,2,3,4,5,6]
Caron et al [10] investigated the anisotropic creep behavior of some advanced superalloys (CMSX-2, Alloy 454, MXON, and CMSX-4) in the temperature ranging from 1033 to 1323 K. He et al [11] discussed the creep/fatigue damage characteristics of DD6 and the results show the capability of DD6 to avoid fatigue damage in [011] direction is better than that in [001] direction
Wu et al [13] made extensile and compression tests at different temperatures on DD8 with various strain rates and the results indicate that the tendency to the plastic deformation inhomogeneity decreases in the order of [011], [001], and [111]
Summary
Single-crystal nickel-based superalloys are widely used as blade of modern gas turbine aeroengines, as they significantly raise the operation temperature and efficiency due to excellent mechanical properties in service [1,2,3,4,5,6]. Their excellent high-temperature properties are superior to conventional cast alloys, such as high-temperature creep and oxidation-resistant performance, which results from the elimination of grain boundaries in single-crystal alloys. The previous investigations mainly concentrated on the fatigue life and creep properties with different orientations, while other fundamental performances of materials, such as hardness, Young’s modulus, and yield stress are rarely focused on
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