The hot corrosion behavior of a Ni?20Cr?18W (mass fraction, %) superalloy in the mixture of 75%Na 2 SO 4?25%NaCl melts at 700 and 800 °C was studied. The results demonstrate that the alloy suffers from serious ho...The hot corrosion behavior of a Ni?20Cr?18W (mass fraction, %) superalloy in the mixture of 75%Na 2 SO 4?25%NaCl melts at 700 and 800 °C was studied. The results demonstrate that the alloy suffers from serious hot corrosion attack in the mixture molten salt. Meanwhile, the degradation of the substrate accelerates with increasing the corrosion temperature. The corrosion layer has an obvious duplex microstructure, and the Cr-depletion zone is detected obviously nearby the inner corrosion layer. The main corrosion products at 700 and 800 °C are almost the same and mainly include NiO, Cr2O3and Ni3S2, but a trace amount of NiCrO2 is detected at 800 °C for 20 h. The hot corrosion mechanism and formation mechanism of corrosion scales of the Ni?20Cr?18W superalloy in the molten salt are proposed.展开更多
The effect of hot compression on the grain boundary segregation and precipitation behavior of M6C carbide in theNi-20Cr-18W-1Mo superalloy was investigated by thermomechanical simulator, scanning electronic microscope...The effect of hot compression on the grain boundary segregation and precipitation behavior of M6C carbide in theNi-20Cr-18W-1Mo superalloy was investigated by thermomechanical simulator, scanning electronic microscope （SEM） and X-raydiffraction （XRD）. Results indicate that the amount of M6C carbides obviously increases in the experimental alloy after hotcompression. Composition analyses reveal that secondary M6C carbides at grain boundaries are highly enriched in tungsten.Meanwhile, the secondary carbide size of compressive samples is 3？5 μm in 10% deformation degree, while the carbide size ofundeformed specimens is less than 1 μm under aging treatment at 900 and 1000 ℃. According to the thermodynamic calculationresults, the Gibbs free energy of γ-matrix and carbides decreases with increase of the compression temperature, and the W-rich M6Ccarbide is more stable than Cr-rich M23C6. Compared with the experimental results, it is found that compressive stress accelerates theW segregation rate in grain boundary region, and further rises the rapid growth of W-rich M6C as compared with the undeformedone.展开更多
基金Project(51171150)supported by the National Natural Science Foundation of China
文摘The hot corrosion behavior of a Ni?20Cr?18W (mass fraction, %) superalloy in the mixture of 75%Na 2 SO 4?25%NaCl melts at 700 and 800 °C was studied. The results demonstrate that the alloy suffers from serious hot corrosion attack in the mixture molten salt. Meanwhile, the degradation of the substrate accelerates with increasing the corrosion temperature. The corrosion layer has an obvious duplex microstructure, and the Cr-depletion zone is detected obviously nearby the inner corrosion layer. The main corrosion products at 700 and 800 °C are almost the same and mainly include NiO, Cr2O3and Ni3S2, but a trace amount of NiCrO2 is detected at 800 °C for 20 h. The hot corrosion mechanism and formation mechanism of corrosion scales of the Ni?20Cr?18W superalloy in the molten salt are proposed.
基金Project(51171150)supported by the National Natural Science Foundation of China
文摘The effect of hot compression on the grain boundary segregation and precipitation behavior of M6C carbide in theNi-20Cr-18W-1Mo superalloy was investigated by thermomechanical simulator, scanning electronic microscope （SEM） and X-raydiffraction （XRD）. Results indicate that the amount of M6C carbides obviously increases in the experimental alloy after hotcompression. Composition analyses reveal that secondary M6C carbides at grain boundaries are highly enriched in tungsten.Meanwhile, the secondary carbide size of compressive samples is 3？5 μm in 10% deformation degree, while the carbide size ofundeformed specimens is less than 1 μm under aging treatment at 900 and 1000 ℃. According to the thermodynamic calculationresults, the Gibbs free energy of γ-matrix and carbides decreases with increase of the compression temperature, and the W-rich M6Ccarbide is more stable than Cr-rich M23C6. Compared with the experimental results, it is found that compressive stress accelerates theW segregation rate in grain boundary region, and further rises the rapid growth of W-rich M6C as compared with the undeformedone.
