On the origin of mosaicity in directionally solidified Ni-base superalloys
| Autor: | Samuel Perry, Karl Tassenberg, Neil D'Souza, Bogdan Nenchev, Genoveva Burca, Ruiyao Zhang, Hongbiao Dong, Joel Strickland, Gareth Sheppard |
|---|---|
| Jazyk: | angličtina |
| Rok vydání: | 2021 |
| Předmět: |
Materials science
Polymers and Plastics Condensed matter physics Turbine blade Metals and Alloys Curvature Casting Mosaicity Electronic Optical and Magnetic Materials law.invention Superalloy Temperature gradient Dendrite (crystal) law Ceramics and Composites Grain boundary Single crystal Directional solidification |
| ISSN: | 1359-6454 |
| Popis: | 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. |
| Databáze: | OpenAIRE |
| Externí odkaz: |
|
Full Text from ScienceDirect