Transverse Stress Rupture Properties of a Nickel-Base Superalloy Bicrystal

Abstract

Effects of low angle boundaries (LABs) on the stress rupture properties of bicrystals of a nickel-based third generation single crystal superalloy at 1093 °C/158 MPa were investigated. The results show that the effect of LABs on the stress rupture elongation of the alloy is higher than that of the stress rupture life at 1093 °C/158 MPa. As the misorientation angle of the LABs reaches 9.0°, the stress rupture life of the alloy with LABs can still retain nearly 50% of that with LABs of 0° at 1093 °C/158 MPa; while the stress rupture elongation of the alloy with LABs drops obviously when the misorientation angle of the LABs is larger than 6.5°. The fracture surfaces of stress ruptured alloy with LABs of 0°~2.9° are characterized by dimple features, while those with LABs of 6.5°~12.3° all exhibit intergranular fracture features. Apparent dimple features can be observed at the intergranular fracture surface of the alloy with LABs of 6.5° and the elongation of it is high. However, obvious dendrite features can be observed at the intergranular fracture surfaces of the alloy with LABs of 7.6°~12.3° and the elongations of them are relatively low.