Effect of annealing treatment on microstructure evolution and creep behavior of a multiphase Ni3Al-based superalloy
Effect of annealing treatment on microstructure evolution and creep behavior of a multiphase Ni3Al-based superalloy
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DOI：
10.1016/j.msea.2018.11.126
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发表时间：
2019-01
期刊：
影响因子：
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通讯作者：
Jing Wu;Chong Li;Yong-chang Liu;Yu-ting Wu;Q. Guo;Huijun Li;Haipeng Wang
中科院分区：
文献类型：
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作者：
Jing Wu;Chong Li;Yong-chang Liu;Yu-ting Wu;Q. Guo;Huijun Li;Haipeng Wang
研究了一种新型铸造多相Ni 3Al基高温合金在高温退火处理下的组织演变和蠕变行为。铸态组织主要由γ′+γ枝晶和少量（~ 19.37vol%）的枝晶间β相组成，1160-1280 °C退火促进了γ ′ + γ枝晶中γ ′ Ⅰ相的生长，枝晶间β相的体积分数保持相对恒定，但在此过程中β相迅速聚集并粗化。同时，退火处理显著促进了准球形α-Cr相颗粒在β相中的析出。原始铸态组织在800 °C/200 MPa下的蠕变抗力较差，蠕变断裂寿命最短为194 h，而1160-1280 °C的退火处理使蠕变断裂寿命延长至611 h以上。虽然稳态蠕变速率随着退火温度的升高而逐渐降低，但与原始铸态组织相比，在1240和1280 °C下的高温退火降低了蠕变延性。1160 °C退火组织的持久寿命最长，为665 h，蠕变断裂应变最大，为3.21%，而1280 °C退火组织的稳态蠕变速率最小，这是由于退火后最大尺寸为0.91 μm的α ′ Ⅰ相。尽管枝晶间β相对Ni 3Al基高温合金的铸造性能、热塑性和焊接性能具有积极作用，但由于其与占主导地位的γ′+γ枝晶的非共格存在，对蠕变性能有负面影响。
The microstructure evolution and creep behavior of a novelly designed as-cast Ni3Al-based superalloy with multiphase configuration are investigated by high-temperature annealing treatments. The as-cast microstructure comprises dominant γ′+γ dendritic and less (~19.37 vol%) interdendritic β areas, annealing treatments at 1160–1280 °C promoted the growth of γ'Ⅰphase in the γ'+γ dendrite, during which the interdendritic β phase aggregated and coarsened rapidly in width with keeping its relatively constant volume fraction. Meanwhile, the annealing treatments significantly promoted the precipitation of quasi-spherical α-Cr phase particles within the β phase. The original as-cast microstructure exhibited inferior creep resistance at 800 °C/200 MPa with the shortest creep rupture life of 194 h, however, the annealing treatments at 1160–1280 °C prolonged the creep rupture life to beyond 611 h. Although the steady-state creep rate was gradually reduced with increasing annealing temperatures, the creep ductility was degraded by higher-temperature annealing at 1240 and 1280 °C compared with original as-cast microstructure. The 1160 °C annealed microstructure exhibited the longest creep rupture life of 665 h and the maximum creep strain to fracture of 3.21%, while the minimum steady-state creep rate was obtained on account of the largest γ'Ⅰphase sized 0.91 µm after annealing at 1280 °C. Despite its positive role in the castability, thermoplasticity and weldability of the explored multiphase Ni3Al-based superalloy, interdendritic β phase has negative effects on the creep properties due to its incoherent existence with the dominant γ′+γ dendrite.