Tensile Properties of DD15 Single Crystal Superalloy at Different Temperature

Abstract

DD15 single crystal nickel-based alloy was prepared by a directional solidification induction heating furnace and its tensile properties were investigated at the 23°C, 400°C, 800 °C, 1100°C and 1140°C. The tensile fracture mechanism of the alloy at different temperature was investigated. Results indicate that tensile strength of the alloy reduces first, increases afterward, and decrease sharply at last as the test temperature rises, while the tensile plasticity exhibit the reverse change trend. The extension strength of the alloy is superior to that of EPM-102 alloy. At 23°C, 400°C and 800°C, the tensile fracture mode of the alloy is quasi-cleavage mechanism, and at 1100°C and 1140°C that is dimple model. As tensile fracture at 23°C, 400°C and 800°C, the γ′ precipitate nearly keeps cube shape, while that becomes rectangular after tensile fracture at 1100°C and 1140°C. The APB and stacking fault can be seen in the γ′ phase at 23°C, 400°C and 800°C. There is dislocation networks at the γ/γ′ interface and the deformation characteristic is dislocation by-passing mechanism at 1100°C and 1140°C.