On the origin of mosaicity in directionally solidified Ni-base superalloys
On the origin of mosaicity in directionally solidified Ni-base superalloys
复制标题
定向凝固镍基高温合金镶嵌性的起源
DOI：
10.1016/j.actamat.2021.117180
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发表时间：
2021
期刊：
影响因子：
9.4
通讯作者：
Strickland J
中科院分区：
文献类型：
--
作者：
Strickland J
本文讨论了小角度晶界的形成，引起镶嵌，一个现象，最近才受到关注，在单晶镍基高温合金领域。在这项工作中，事后先进的显微镜表征技术被用来推断从单晶涡轮机叶片的横截面的枝晶尖端生长动力学。因此，它已能够突出等温线曲率的作用，诱导横向宏观偏析平行于一个不断增长的凝固前沿。使用从飞行时间能量分辨中子成像和新的布拉格浸渍后处理的晶体学数据，它是建立横向宏观偏析诱导小角度晶界，从而引起镶嵌在单晶镍基高温合金。镶嵌表现出良好的相关性与当地的主要间距，其中快速增长的枝晶表现出更大的<001>偏离铸造方向，与那些以较慢的速度增长。根据这些发现，镶嵌性的起源及其对次生颗粒形成的影响进行了讨论。
This article addresses the formation of low angle grain boundaries which give rise to mosaicity, a phenomenon that has only recently received attention in the single crystal Ni-base superalloy field. In this work, post-mortem advanced microscopy characterisation techniques are employed to deduce the dendrite tip growth kinetics from transverse sections of a single crystal turbine blade. As a result, it has been possible to highlight the role of isotherm curvature in inducing lateral macro-segregation parallel to a growing solidification front. Using crystallographic data from time-of-flight energy-resolved neutron imaging and novel Bragg-dip post processing, it is established that lateral macro-segregation induces small angle grain boundaries which gives rise to mosaicity within single crystal Ni-base superalloys. Mosaicity demonstrates good correlation with the local primary spacing, where faster growing dendrites demonstrate greater deviation of <001> from the casting direction, as compared with those growing at a slower rate. In light of these findings, the origin of mosaicity and its implication to secondary grain formation is discussed.