Xiurong Guan
材料科学技术（英）
The effect of chromium (Cr) on solidification and segregation behavior of Re-containing cast Ni-base superalloys was investigated by optical microscopy (OM), scanning electron microscopy (SEM) and electronic probe micro analysis (EPMA). The results show that Cr has significant effect on solidification and segregation behavior of Re-containing cast Ni-base superalloys. The liquidus and solidus of alloy decrease with increasing Cr in alloys. The segregation coe±cient (K) of Mo increases and that of W and Re decreases gradually with increasing Cr element.
关键词:
Superalloy
Weiguo Jiang
材料科学技术（英）
Four castings with different modulus have been designed to simulate different thickness sections of a turbine blade during casting process. The microstructure has been observed by optical microscopy (OM) and scanning electron microscopy (SEM). The micro-segregation was tested by energy dispersive spectroscopy (EDS) and the macro-segregation was analyzed by using Metalscan 2500 spectrometers. The experimental results show that the microstructure of casting is affected by modulus apparently. The smaller the modulus, the finer the microstructure. The average grain size of castings with modulus of 0.29, 1.57, 3.16 and 5.0 mm is 0.3, 1.5, 2.7 and 4.3 mm, and the volume fraction of eutectic is 0, 0.1%, 0.2% and 1.0%, respectively. The micro/macro segregation is affected by the modulus apparently. The smaller the modulus, the lower the segregation level. When the modulus of casting increases, the content of Al increases, while the content of W, Cr and Mo decreases both in inner grain and near grain boundary. The content of Al and Mo in inner grain is higher than that near grain boundary, while the content of Cr and W in inner grain is lower than that near grain boundary.
关键词:
Superalloy
Xiurong Guan Enze Liu Zhi Zheng Yongsi Yu Jian Tong Yuchun Zhai
材料科学技术（英）
The effect of chromium (Cr) on solidification and segregation behavior of Re-containing cast Ni-base superalloys was investigated by optical microscopy (OM), scanning electron microscopy (SEM) and electronic probe micro analysis (EPMA). The results show that Cr has significant effect on solidification and segregation behavior of Re-containing cast Ni-base superalloys. The liquidus and solidus of alloy decrease with increasing Cr in alloys. The segregation coe±cient (K) of Mo increases and that of W and Re decreases gradually with increasing Cr element.
关键词:
Superalloy
Weiguo JIANG
金属学报(英文版)
A novel grain refiner composed of nickel, tungsten and yttria was prepared by the powder metallurgy way. The microstructure of the refiner alloy was studied by optical microscope (OM), scanning electron microscope (SEM) and energy dispersive spectroscopy (EDS). The refinement process was simplized. It was shown that the alloy grains could be refined by addition of the refiners apparently even at high pouring temperature. The average grain size of the refiner free alloy was 4~mm, and 0.4 mm for the refined alloy. The fine-grain superalloy has excellent mechanical properties at intermediate temperature. The refinement mechanism was discussed.
关键词:
Superalloy
Liufa LIU
,
Chen LU
,
Wenjiang DING
,
Akio Hirose
,
Kojiro F.Kobayashi
材料科学技术（英）
The effect of δ phase on the hydrogen embrittlement (HE) sensitivity of Inconel 718 was investigated by conducting notch tensile tests. Notch tensile specimens with various precipitation morphologies of δ phase were prepared with different heat treatments, and hydrogen was charged into the tensile specimens before tensile tests via a cathodic charging process. The loss of notch tensile strength (NTS) due to the charged hydrogen was used to evaluate the hydrogen embrittlement sensitivity. The results show that δ phase has deleterious effect on NTSs, and the fracture of hydrogen-charged specimens initiated near the notch surfaces. The loss of NTS caused by precharged hydrogen can be greatly decreased by dissolving δ phase. δ-free Inconel 718 alloy is proposed for the applications in hydrogen environments.
关键词:
Superalloy
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null
,
null
,
null
Shuai WANG
金属学报(英文版)
Hot compression test was carried out at 1000 ℃ to investigate the dynamic recrystallization nucleation mechanism of a nickel-base superalloy. It was found that the bulging of original grain boundaries was inhibited by carbides and deformation twins at the boundaries. Recrystallized nuclei evolved from the subgrains of dislocation reconfiguration along original grain boundaries, and the growth of the potential nuclei was carried out by the coalescence of subgrains. The necklace structure of recrystallized grains along original grain boundaries was attributed to the strain gradient from grain boundary to grain interior.
关键词:
Dynamic recrystallization
Pingli MAO
,
Yan XIN
,
Ke HAN
,
Weiguo JIANG
金属学报(英文版)
doi:10.1016/S1006-7191(08)60110-6
The volume fraction and morphology of the TCP-phase formed in two kinds of Ni-Mo-Cr-Re superalloys under different heat treatment conditions were investigated in this paper. In Re-5% alloy, with increasing of the heat treatment temperature and prolonging the holding time, the volume fraction of TCP-phase decreased and the TCP-phase size increased. At relatively lower temperature, the TCP-phase prefers to present in the dendrite cores. In Re-10% alloy, the volume fraction and size have the same change tendency as that of in Re-5% alloy, but the morphology will change from needle-like and block-like to sphere when the temperature increases. The TCP-phases formed in these two Ni-Mo-Cr-Re alloys are σ and P phase.
关键词:
Heat treatment
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null
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