Solidification behavior of a Ni-based single crystal CMSX-4 superalloy solidified by downward directional solidification process
Solidification behavior of a Ni-based single crystal CMSX-4 superalloy solidified by downward directional solidification process
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DOI：
10.1016/j.matchar.2015.01.003
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发表时间：
2015-03-01
影响因子：
4.7
通讯作者：
Buehrig-Polaczek, A.
中科院分区：
文献类型：
--
作者：
Wang, F.;Ma, D.;Buehrig-Polaczek, A.
采用定向凝固淬火技术研究了CMSX-4高温合金单晶向下定向凝固的凝固行为。通过对两相区横截面的分析，得到了凝固路径、固相体积分数（f（s））随温度的变化规律以及共晶熔池的凝固顺序。f（s）随温度的降低而单调增加。在凝固间隔的前20%内，f（s）增加约60%。这种增长比例随后显著降低。它在最后部分变得平坦，直到（γ + γ '）共晶凝固。Lever规则和Scheil模型不能描述实验中观察到的f（s）的实际演化;然而，Bower-Brody-Flemings模型可以在一定程度上描述这种演化。凝固路径描述为：γ相初晶化，凝固终止与共晶反应。共晶熔池的凝固顺序从枝晶间中心或与γ相相邻的细小（γ + γ '）组织开始，然后在空间上发展为花瓣状的粗大（γ + γ'）组织。在该顺序之后，γ '颗粒从撞击的粗糙花瓣状γ'相之间的γ相沉淀。(C)2015 Elsevier Inc. All rights reserved.
The solidification behavior of a CMSX-4 superalloy single crystal solidified using the downward directional solidification process has been investigated by using the directional solidification quenching technique. An analysis of transverse sections within the mushy zone yielded the solidification path, the evolution of solid volume fraction (f(s)) with the temperature decrease and the solidification sequence of eutectic pool. f(s) monotonically increased with decreasing temperature. Within the first 20% of the solidification interval, f(s) increased by about 60%. This increasing ratio then significantly reduced. It became flat at the final portion up to the freezing of (gamma + gamma') eutectic. The Lever rule and Scheil model cannot describe the actual evolution of f(s) observed in the experiment; however, the Bower-Brody-Flemings model can, to some extent, depict this evolution. The solidification path was described as: primary crystallization of gamma phase; termination of solidification with a eutectic reaction. The solidification sequence of the eutectic pool commenced with a fine (gamma + gamma') structure in the center of interdendritic regions or adjacent to gamma phases, then progressed spatially and developed a petal-like coarse (gamma + gamma') structure. Following this sequence, the gamma' particles precipitate from the gamma phase between the impinging coarse petal-like gamma' phases. (C) 2015 Elsevier Inc. All rights reserved.