Advanced Scale Bridging Microstructure Analysis of Single Crystal Ni-Base Superalloys
Advanced Scale Bridging Microstructure Analysis of Single Crystal Ni-Base Superalloys
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DOI：
10.1002/adem.201400136
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发表时间：
2015-02-01
影响因子：
3.6
通讯作者：
Eggeler, Gunther
中科院分区：
文献类型：
--
作者：
Parsa, Alireza B.;Wollgramm, Philip;Eggeler, Gunther
在目前的工作中，我们展示了如何传统的和先进的机械，化学和微观结构的方法可以用来表征铸造单晶镍基高温合金（SX）板跨越多个长度尺度。两种类型的显微组织不均匀性是重要的，与铸造显微组织（枝晶（D）和枝晶间（ID）区域-大尺度不均匀性）和与众所周知的γ/γ '显微组织（小尺度不均匀性）相关。使用电子探针显微分析（EPMA），我们可以表明Re、Co和Cr等元素分配到枝晶中，而ID区域含有更多的Al、Ta和Ti。分析透射电子显微镜和原子探针层析成像（APT）显示Al、Ta和Ti分配到γ '立方体，而γ通道显示较高浓度的Co、Cr、Re和W。我们可以结合联合收割机大尺度（EPMA）和小尺度分析方法（APT），以获得在枝晶和ID区域中的γ '体积分数的合理估计。在本工作中研究的SX板的化学和机械性能是均匀的，当它们被确定从γ '体积的尺寸，这是显着大于枝晶间距。对于SX板（140 mm × 100 mm × 20 mm）在本工作中研究，这适用于平均化学成分以及弹性行为和局部蠕变性能。我们强调了HRTEM和APT的潜力，有助于更好地理解位错的作用，在γ '相的粗化和高温暴露后的冷却速率对微观结构的影响。
In the present work, we show how conventional and advanced mechanical, chemical, and microstructural methods can be used to characterize cast single crystal Ni-base superalloy (SX) plates across multiple length scales. Two types of microstructural heterogeneities are important, associated with the castmicrostructure (dendrites (D) and interdendritic (ID) regions - large scale heterogeneity) and with the well-known gamma/gamma' microstructure (small scale heterogeneity). Using electron probe microanalysis (EPMA), we can show that elements such as Re, Co, and Cr partition to the dendrites while ID regions contain more Al, Ta, and Ti. Analytical transmission electron microscopy and atom probe tomography (APT) show that Al, Ta, and Ti partition to the gamma' cubes while gamma channels show higher concentrations of Co, Cr, Re, and W. We can combine large scale (EPMA) and small-scale analytical methods (APT) to obtain reasonable estimates for gamma' volume fractions in the dendrites and in the ID regions. The chemical and mechanical properties of the SX plates studied in the present work are homogeneous, when they are determined from gamma' volumes with dimensions, which are significantly larger than the dendrite spacing. For the SX plates (140 mm x 100 mm x 20 mm) studied in the present work this holds for the average chemical composition as well as for elastic behavior and local creep properties. We highlight the potential of HRTEM and APT to contribute to a better understanding of the role of dislocations during coarsening of the gamma' phase and the effect of cooling rates after high temperature exposure on the microstructure.