Study On Microstructure And Mechanical Properties Of Powder Superalloy FGH96/97

This thesis studies the microstructures of FGH96 alloy samples prepared using spark plasma sintering(SPS)and hot extrusion(HEx)and FGH97 alloy samples prepared hot isostatic pressing(HIP)and their room temperature and elevated temperature(750 ? and 850 ?)tensile mechanical properties.The microstructural characterization and fracture morphology examination were performed using X-ray diffractometry(XRD),optical microscopy(OM),scanning electron microscopy(SEM),electron beam scattering diffraction(EBSD)and transmission electron microscopy(TEM).The results show that both manufacture process routes achieve full density of the FGH96 and FGH97 alloy samples.The FGH96 alloy samples prepared by SPS and HEx have small grain sizes in the range of 10~60?m,while the FHG97 alloy samples prepared by HIP have relatively large grain sizes in the range of 30~100?m.Both FGH96 alloy and FGH97 alloy are ?' phase precipitate-hardening superalloys.Tensile test results show that FGH96 alloy and FGH97 alloy samples have relatively good tensile strength at room temperature and 750?,but their tensile strength is significantly reduced at 850?.FGH96 alloy and FGH97 alloy samples have good plasticity at room temperature,but as the temperature increases,the plasticity is reduced and the fracture becomes brittle.FGH96 alloy samples still have good plasticity at 750?,and become brittle at 850?.On the hand,FGH97 alloy samples become brittle at 750?.The microstructures of both alloys are stable during high temperature tensile testing,without grain growth and coarsening and rafting of ?' precipitates.