Microstructure and high-temperature tensile behavior of superalloy prepared by hot oscillatory pressing

Abstract

Powder metallurgy (PM) superalloys have been widely used in hot-end components of turbine engines. However, the occurrence of prior particle boundaries (PPBs) during superalloys consolidation detriments its mechanical properties, and additional hot working is required to eliminate PPBs. In this article, a novel hot oscillatory pressing (HOP) method was proposed to prepare PM superalloys. Microstructure and high-temperature tensile behavior of HOPed superalloys were investigated using scanning electron microscopy (SEM), electron probe micro-analyzer (EPMA), electron backscatter diffraction (EBSD), and compared with those of superalloys fabricated by hot pressing (HP) and hot isostatic pressing (HIP). The result shows that the oscillatory pressure can effectively inhibit the formation of prior particle boundaries (PPBs). Compared to the HPed sample, the HOPed sample exhibited improved mechanical properties. The ultimate tensile strength and elongation of the HOPed sample at 700 °C are 1084 MPa and 19.5%, respectively, which is markedly better than those of the HPed sample and comparable to those of the sample prepared by hot isostatic pressing (HIP) at higher pressure and longer time. These findings suggest that HOP is likely a promising technique for making superalloys.