Microstructure evolution and tensile behavior of hot pressed powder metallurgy superalloys

Hot press (HP) technology is used to explore the feasibility of preparing small civil superalloy parts in this paper. Microstructure of the samples was characterized by optical microscopy, scanning electron microscopy, electron-probe microanalysis, and so on. The results show that when HPing temperature is 1080 °C, the tensile properties of the materials are best. Its ultimate tensile strength and elongation are 1414 ± 19 MPa and 31.1 ± 3.5%, respectively, values comparable to that of materials prepared by hot isostatic pressing (HIP). When HPing temperature is lower or higher than 1080 °C, the pore or prior particle boundaries (PPBs) are the main defects affecting superalloy tensile properties. The cracks are prone to initiate from pores or PPB precipitates, and propagate along particle boundaries, presenting lower tensile properties and inter-particle fracture predominately.