Microstructure and Tensile Behavior of a Novel Monocrystalline Co-Based Superalloy at Different Temperatures

Microstructures and tensile properties of a novel monocrystalline Co-based superalloy are investigated by experiments and finite element simulation. Microstructures of heat-treated alloys are composed of γ and cubical γ' precipitates without the presence of the secondary phase, and the fraction of γ' phase is about 86%. The experimental results show that tensile properties of the novel monocrystalline Co-based superalloy have abnormal yield behavior. In low and medium temperature ranges (R.T. 850 °C), the yield stress increases gradually with temperature increase and the tensile fracture surface is characterized by cleavage rupture. At 850 °C, fracture mechanism is composite of cleavage and microporous. While above 850 °C, the yield stress decreases rapidly, and fracture surface is constituted of mixed fracture surface of dimples and micropores. The simulation results show that the tensile stress-–strain curves are well fitted to the experimental data at different temperatures.