Super-clean and super-spherical FGH4095 superalloy powder is produced by the ceramic-free electrode inductionmelt inert gas atomization（EIGA） technique.A continuous and steady-state liquid metal flow is achieved at ...Super-clean and super-spherical FGH4095 superalloy powder is produced by the ceramic-free electrode inductionmelt inert gas atomization（EIGA） technique.A continuous and steady-state liquid metal flow is achieved at high-frequency（350 k Hz） alternating current and high electric power（100 k W）.The superalloy is immersed in a high-frequency induction coil,and the liquid metal falling into a supersonic nozzle is atomized by an Ar gas of high kinetic gas energy.Numerical calculations are performed to optimize the structure parameters for the nozzle tip.The undesired oxidation reaction of alloying elements starts at 1000℃ with the reaction originating from the active sites on the powder surfaces,leading to the formation of oxides,MexOy.The role of active sites and kinetic factors associated with the diffusion of oxygen present in the atomization gas streams are also examined.The observed results reveal that the oxidation process occurring at the surface of the produced powders gradually moves toward the core,and that there exists a clear interface between the product layer and the reactant.The present study lays a theoretical foundation for controlling the oxidation of nickel-based superalloy powders from the powder process step.展开更多
High temperature oxidation behaviors of FGH96 P/M superaUoy have been studied in air at temperatures ranging from 600 to 1000℃. By means of isothermal oxidation testing, X-ray diffraction, SEM （scanning electron mic...High temperature oxidation behaviors of FGH96 P/M superaUoy have been studied in air at temperatures ranging from 600 to 1000℃. By means of isothermal oxidation testing, X-ray diffraction, SEM （scanning electron microscopy）, and EDS （energy dispersive X-ray spectroscopy） analyses, the oxidation kinetics as well as the composition and morphology of scales were investigated. Thermodynamic calculations were used to explain the oxidation mechanism. The results showed that as the oxidation temperature increased, the oxidation rate, the scale thickness, and scale spallation increased. FGH96 P/M superalloy exhibits good oxidation resistance at temperature below 800℃. The oxidation kinetics follows an approximately parabolic rate law, and the oxide layer was mainly composed of Cr2O3 TiO2 and a little amount of NiCr2O4. The oxidation is controlled by the transmission of chromium. titanium, and oxygen through the oxide scale.展开更多
FGH 95 is a powder metallurgy （P/M） processed superalloy, which was developed in the 1980s in China. One of the applications of FGH 95 was high pressure turbine blade retainers. The manufacturing processes used to p...FGH 95 is a powder metallurgy （P/M） processed superalloy, which was developed in the 1980s in China. One of the applications of FGH 95 was high pressure turbine blade retainers. The manufacturing processes used to produce FGH 95 blade retainers consisted of atomization by plasma rotating electrode process （PREP）, hot isostatic pressing （HIP） at super-solvus temperature and a sub-solvus solution heat treatment. The material had an equiaxed grain structure （ASTM 6.5-7.5）. The γ precipitates in as-HIP FGH 95 showed a tri-model distribution. Carbides in the alloy were MC type and precipitated at grain boundaries. The prior particle boundaries （PPB） in the material originated mainly from γ＇ phase. Statistics of the mechanical properties data from batch production of the FGH 95 blade retainers were investigated. The as-HIP FGH 95 blade retainers showed high strength at room temperature and 650 ℃, excellent creep resistance and outstanding stress rupture strength at 650 ℃.展开更多
文摘Super-clean and super-spherical FGH4095 superalloy powder is produced by the ceramic-free electrode inductionmelt inert gas atomization（EIGA） technique.A continuous and steady-state liquid metal flow is achieved at high-frequency（350 k Hz） alternating current and high electric power（100 k W）.The superalloy is immersed in a high-frequency induction coil,and the liquid metal falling into a supersonic nozzle is atomized by an Ar gas of high kinetic gas energy.Numerical calculations are performed to optimize the structure parameters for the nozzle tip.The undesired oxidation reaction of alloying elements starts at 1000℃ with the reaction originating from the active sites on the powder surfaces,leading to the formation of oxides,MexOy.The role of active sites and kinetic factors associated with the diffusion of oxygen present in the atomization gas streams are also examined.The observed results reveal that the oxidation process occurring at the surface of the produced powders gradually moves toward the core,and that there exists a clear interface between the product layer and the reactant.The present study lays a theoretical foundation for controlling the oxidation of nickel-based superalloy powders from the powder process step.
文摘High temperature oxidation behaviors of FGH96 P/M superaUoy have been studied in air at temperatures ranging from 600 to 1000℃. By means of isothermal oxidation testing, X-ray diffraction, SEM （scanning electron microscopy）, and EDS （energy dispersive X-ray spectroscopy） analyses, the oxidation kinetics as well as the composition and morphology of scales were investigated. Thermodynamic calculations were used to explain the oxidation mechanism. The results showed that as the oxidation temperature increased, the oxidation rate, the scale thickness, and scale spallation increased. FGH96 P/M superalloy exhibits good oxidation resistance at temperature below 800℃. The oxidation kinetics follows an approximately parabolic rate law, and the oxide layer was mainly composed of Cr2O3 TiO2 and a little amount of NiCr2O4. The oxidation is controlled by the transmission of chromium. titanium, and oxygen through the oxide scale.
文摘FGH 95 is a powder metallurgy （P/M） processed superalloy, which was developed in the 1980s in China. One of the applications of FGH 95 was high pressure turbine blade retainers. The manufacturing processes used to produce FGH 95 blade retainers consisted of atomization by plasma rotating electrode process （PREP）, hot isostatic pressing （HIP） at super-solvus temperature and a sub-solvus solution heat treatment. The material had an equiaxed grain structure （ASTM 6.5-7.5）. The γ precipitates in as-HIP FGH 95 showed a tri-model distribution. Carbides in the alloy were MC type and precipitated at grain boundaries. The prior particle boundaries （PPB） in the material originated mainly from γ＇ phase. Statistics of the mechanical properties data from batch production of the FGH 95 blade retainers were investigated. The as-HIP FGH 95 blade retainers showed high strength at room temperature and 650 ℃, excellent creep resistance and outstanding stress rupture strength at 650 ℃.
