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对新型镍基粉末高温合金FGH98Ⅰ分别进行过固溶和过固溶+亚固溶后处理,利用场发射扫描电镜和显微硬度仪研究了冷却速度对合金γ′相析出和显微硬度的影响。结果表明:随着固溶冷却速度增加,合金中二次和三次γ′相的尺寸减小,二次γ′相形状从蝶形向球形转变,γ′相的形状因子和颗粒密度增大,面积分数和晶界表观宽度减小。在冷却速度≤1.4℃/s时,冷却γ′相分两阶段形核;冷速越快,合金的硬度越高,时效后硬度增高越多;过固溶处理后的亚固溶处理使冷却γ′相粗化和方形化,形状因子减小,晶界γ′相析出密集区消失,硬度降低。另外,还建立了冷速与γ′相平均尺寸和合金硬度之间的函数关系式。该结果为FGH98Ⅰ合金实际双性能盘固溶热处理工艺的选择提供了理论参考。
The effects of cooling rate on the γ’phase precipitation and microhardness of the alloy were investigated by field emission scanning electron microscopy and microhardness tester, respectively, for the new nickel-based superalloy FGH98Ⅰ. . The results show that the size of secondary and tertiary γ ’phase decreases with the increase of solution cooling rate. The shape of secondary γ’ phase changes from butterfly to sphere, the shape factor and particle density of γ ’phase increase, The area fraction and the apparent width of the grain boundaries decrease. When the cooling rate is less than or equal to 1.4 ℃ / s, the cooled γ ’phase is nucleated in two stages. The faster the cooling rate is, the higher the hardness of the alloy is and the more the hardness increases after aging. The subsolidation treatment after solution treatment causes the cooling The γ ’phase coarsens and squares, the shape factor decreases, and the grain boundary γ’phase precipitates in the dense zone and the hardness decreases. In addition, the relationship between the cooling rate and the average size of γ ’and the hardness of the alloy was also established. The results provide a theoretical reference for the selection of practical dual-performance solution heat treatment process of FGH98Ⅰ alloy.