The quantification of key microstructural parameters as a function of aging or creep exposure time is commonplace in the assessment of 9Cr Creep Strength Enhanced Ferritic (CSEF) power-plant steels. In these studies, the sample is either assumed chemically homogenous at the micro-scale or that a material average will be achieved by collecting enough images at random locations. In this paper, the micro-scale chemical homogeneity of two ex-service boiler components, a pipe and a forging, are quantitatively assessed using high sensitivity chemical mapping from µ-XRF. The compositional variation was as expected most pronounced in the larger elements Mo and Nb, where a > 20 pct difference in composition was present between positively and negatively segregated areas. The effect of this micro-segregation on local variations in Laves phase particle characteristics was investigated using SEM images. This showed a factor of two difference in the number of particles and the area coverage between positively and negatively Mo-segregated regions. This result was consistent with the thermodynamic equilibrium predictions of the phase content based on the observed level of segregation.

在9Cr蠕变强度增强铁素体（CSEF）电厂钢的评估中，随老化或蠕变暴露时间而变的关键微结构参数的量化是很常见的。在这些研究中，假定样品在微观尺度上是化学均质的，或者通过在随机位置收集足够的图像将获得平均材料。在本文中，使用μ的高灵敏度化学图谱定量评估了两个退役锅炉部件（管道和锻件）的微观化学均质性。-XRF。如预期的那样，在较大的元素Mo和Nb中，成分变化最为明显，在正隔离区域和负隔离区域之间存在> 20 pct的成分差异。使用SEM图像研究了这种微偏析对Laves相颗粒特征局部变化的影响。这表明在正和负的Mo偏析区域之间，颗粒数量和面积覆盖率存在两个差异。该结果与基于观察到的偏析水平的相含量的热力学平衡预测一致。