Research on microstructure characterization in residual dendrite zones of FGH96 alloy with gradient microstructure
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摘要: 采用梯度热处理工艺制备了具有梯度组织结构的FGH96合金亚尺寸盘坯, 对盘坯存在的残留枝晶区组织进行了研究。结果表明, 残留枝晶区实质上是一种γ′相未完全再结晶的组织区, 其呈区域性不均匀的分布于盘芯部位。残留枝晶区的形成与粉末颗粒冷凝组织的遗传性及未充分变形再结晶密切相关, 通过采用合适的热加工和固溶热处理工艺可以消除这种组织不均匀性。Abstract: The subscale FGH96 alloy disk with the gradient microstructure was prepared using gradient heat treatment. Microstructure characterization of residual dendrite zones was investigated. The results show that, the residual dendrite zone of FGH96 alloy disk is an incomplete recrystallization zone where γ′ phases exhibit the uneven distribution in disk core. The formation of residual dendrite zone is closely related to the solidification heredity of powder particles and incomplete deformation recrystallization, the inhomogeneity in residual dendrite zone can be eliminated by the suitable hot working and solution heat treatment.
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表 1 FGH96合金化学成分(质量分数)
Table 1. Chemical composition of FGH96 alloy
% Co Cr Mo W Al Ti Nb B Zr C Ni 12.9 15.8 4.0 4.0 2.2 3.7 0.8 0.011 0.036 0.03 余量 表 2 残留枝晶区和等轴晶粒区γ′相析出特征
Table 2. Precipitation characteristics ofγ′ precipitates in RDZ and EGZ
析出特征 初始γ′相 二次γ′相 三次γ′相 梯度组织热处理 亚固溶处理 残留枝晶区 形状 简单枝晶,不规则方形 蝶形,不规则方形 圆角方形 球形 尺寸 0.2~1.0μm 60~180nm 30~60nm 10~30nm 颗粒密度 高 低 高 低 等轴晶粒区 形状 不规则方形 带突起的方形 球形 球形 尺寸 1~3μm 70~200nm 30~50nm < 30nm 颗粒密度 低 高 低 高 -
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