Anisotropic creep behavior of aluminized Ni-based single crystal superalloy TMS-75

We examined the creep behavior of aluminized Ni-based single crystal superalloy TMS-75 with {100} and {110} side-surfaces. The specimens were aluminized by pack aluminizing treatment at 1000 °C for 5 h under argon flow. The creep rupture tests were performed at 900 °C under a stress of 392 MPa. The stress orientation of all of the specimens was within 4° of 〈001〉. It was evident that the {100} specimens exhibited higher creep rupture lives compared to the {110} specimens, indicating that anisotropy of the secondary orientation—which is normal in the primary orientation—occurred. The anisotropic creep behavior of the aluminized specimens was induced primarily by the different arrangements of {111} 〈101〉 slip systems between the two side-surface orientations. The gradient of hardness values in the coating-to-substrate regions and depth of TCP penetration were additional degradation factors.