Study on oxide inclusions of nickel-based P/M superalloy FHG96 by computed tomography technology

The sensitivity of oxide inclusions (Al₂O₃, SiO₂, and mullite) in nickel-based powder metallurgy (P/M) superalloy (FGH96) to different processing technology was studied by computed tomography (CT) technology. The results show that, the process of hot isostatic pressing + isothermal forging can significantly reduce the Al₂O₃ inclusion size and decrease the content of Al₂O₃ inclusion in FGH96 alloy; the process of hot isostatic pressing + hot extrusion + isothermal forging can effectively reduce the content of SiO₂ inclusion in the alloy; the mullite inclusions are sensitive to both the process of hot isostatic pressing + hot extrusion + isothermal forging and the process of hot isostatic pressing + isothermal forging, and the effects of the two processes are similar. The inclusions in the actual disc show the oil cake shaped, which greatly deteriorates the low cycle fatigue properties of the alloy. The closer the inclusions are to the sample surface, the more obvious the deterioration of low cycle fatigue properties is. Overall, the process of hot isostatic pressing + isothermal forging shows the good effect on reducing the inclusion size, providing an important reference to eliminate the influence of inclusions in alloys by the appropriate process.