Abstract:The effect of heat treatment on the microstructure and mechanical properties of a high-boron Ni3Al-based superalloy was investigated by scanning electron microscope, tensile test and stress rupture test. The results show that when the solid solution temperature increases from 1080 ℃ to 1150 ℃, the volume fraction of γ′ phase in dendrite trunk decreases gradually, the morphology changes from blocky to spherical, and fine tertiary γ′ phases are precipitated inside the γ channel. When the temperature rises from 1080 ℃ to 1120 ℃, the skeleton-like primary borides are partially dissolved, and the granular secondary borides are precipitated. The precipitation tendency of secondary borides is increased with the increase in temperature, and the borides are completely dissolved when the temperature rises to 1150 ℃. After aging at 900 ℃ for 10 h, the alloy solid-solution-treated at 1080 ℃ achieves the ultimate tensile strength of 900 MPa during the tensile test at 800 ℃ and the stress rupture life of 144.5 h under the condition of 580 MPa/800 ℃, exhibiting the best comprehensive mechanical properties. Therefore, the optimal heat treatment process of the test alloy is 1080 ℃×4 h→air cooling+900 ℃×10 h→air cooling.