The effect of platinum(a rare metal)-aluminide coating parameters on the tensile properties of nickel-based superalloy Rene■80 was evaluated at 871℃.For this purpose,initial layers of platinum with different thickne...The effect of platinum(a rare metal)-aluminide coating parameters on the tensile properties of nickel-based superalloy Rene■80 was evaluated at 871℃.For this purpose,initial layers of platinum with different thicknesses(2,4,6 and 8μm)were coated on tensile samples Then,low-temperature high-activity(LTHA)and hightemperature low-activity(HTLA)processes were used for aluminizing.Results of microstructural evaluations using scanning electron microscope(SEM)and phase analysis by X-ray diffraction(XRD)showed a three-layer structure coating for different platinum layer thicknesses and both aluminizing processes.Increasing the thickness of the platinum layer from 2 to 8μm led to the improvement in the final coating thickness from 91.6 to 102.1μm in HTLA.This increase was from 128.1 to 148.6μm in LTHA.The results of hot tensile tests at 871℃ showed a decrease in strength properties of the coated samples compared to the uncoated ones.However,HTLA and high thicknesses of the initial platinum layer showed an intense reduction.The results of fractographic evaluations abou uncoated samples showed a ductile fracture.On the other hand,coated samples showed a simultaneous ductile and brittle fracture failure mechanism.But the main fracture morphology was brittle cleavage fracture which was for the HTLA.展开更多
文摘The effect of platinum(a rare metal)-aluminide coating parameters on the tensile properties of nickel-based superalloy Rene■80 was evaluated at 871℃.For this purpose,initial layers of platinum with different thicknesses(2,4,6 and 8μm)were coated on tensile samples Then,low-temperature high-activity(LTHA)and hightemperature low-activity(HTLA)processes were used for aluminizing.Results of microstructural evaluations using scanning electron microscope(SEM)and phase analysis by X-ray diffraction(XRD)showed a three-layer structure coating for different platinum layer thicknesses and both aluminizing processes.Increasing the thickness of the platinum layer from 2 to 8μm led to the improvement in the final coating thickness from 91.6 to 102.1μm in HTLA.This increase was from 128.1 to 148.6μm in LTHA.The results of hot tensile tests at 871℃ showed a decrease in strength properties of the coated samples compared to the uncoated ones.However,HTLA and high thicknesses of the initial platinum layer showed an intense reduction.The results of fractographic evaluations abou uncoated samples showed a ductile fracture.On the other hand,coated samples showed a simultaneous ductile and brittle fracture failure mechanism.But the main fracture morphology was brittle cleavage fracture which was for the HTLA.
