定向凝固DD6单晶高温合金枝晶组织均匀性研究

发布时间：2018-06-14 19:38

本文选题：镍基单晶高温合金 + 组织均匀性　；参考：《金属学报》2015年09期

【摘要】：采用一次枝晶间距、最小生成树(minimum spanning tree,MST)、Voronoi多边形、FFT以及RO-XRD和EBSD等方法,研究了DD6单晶高温合金枝晶分布的均匀性.结果表明:DD6单晶高温合金一次枝晶平均间距为325.7 mm,变化率7.38%.Voronoi多边形法给出的最近邻枝晶个数对应在5.87~5.93,所占比例变化率超过30%;另外,MST的枝干长度变化也比较明显,达到26.95%,不同位置处的FFT频谱也不同,说明实验中选晶法获得的DD6单晶高温合金组织均匀性有待于进一步提高.上述结果也表明,定向凝固单晶高温合金枝晶生长是一个动态调整的过程,通过测量一次枝晶间距结合Voronoi多边形和MST法可量证枝晶生长过程的变化程度,而通常采用一次枝晶平均间距来衡量凝固过程稳定性是不充分的.对选晶法获得的DD6单晶高温合金择优取向与轴向(Z轴)之间的偏离角进行了测量,发现其值在10°以内,EBSD测试的结果比ROXRD相应结果大,这是由于RO-XRD在计算偏离角时选用了强度最大值所对应的衍射峰所致.
[Abstract]:The uniformity of dendritic distribution in DD6 single crystal superalloys was studied by means of primary dendrite spacing, minimum spanning treedoff, Voronoi polygon, RO-XRD and EBSD. The results show that the average primary dendritic spacing is 325.7 mm, and the variation rate is 7.38%. Voronoi polygonal method shows that the number of nearest dendrites is 5.87% 5.93, and the ratio of variation is more than 30%, in addition, the length of branch and stem of MST also changes obviously. The difference of FFT spectrum at different positions indicates that the microstructure uniformity of DD6 single crystal superalloy obtained by the method of crystal selection in the experiment needs to be further improved. The results also show that the dendritic growth of directionally solidified single crystal superalloy is a dynamic adjustment process. The change of dendritic growth process can be measured by measuring the primary dendritic spacing and Voronoi polygon and MST method. However, it is not sufficient to measure the stability of solidification process by using the average spacing of primary dendrites. The deviation angle between the preferred orientation and the axial Z axis of DD6 single crystal superalloy obtained by single crystal selection method was measured. It was found that the results of EBSD measurement of DD6 single crystal superalloy within 10 掳were larger than those of the corresponding results of ROXRD. This is due to the use of the diffraction peak corresponding to the maximum intensity in the calculation of the deviation angle by RO-XRD.
【作者单位】：西北工业大学凝固技术国家重点实验室;
【基金】：国家自然科学基金项目51323008 中央高校基本科研业务费专项基金3102014JCQ01021 凝固技术国家重点实验室(西北工业大学)自主研究课题101-QP-2014资助~~
【分类号】：TG132.3

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