In situ observation of crystal rotation in Ni-based superalloy during additive manufacturing process
Dongsheng Zhang, Wei Liu, Yuxiao Li, Darui Sun, Yu Wu, Sheng‐Nian Luo, Sen Chen, Ye Tao, Bingbing Zhang
Abstract
Understanding the dynamic process of epitaxial microstructure forming in laser additive manufacturing is very important for achieving products with a single crystalline texture. Here, we perform in situ, real-time synchrotron Laue diffraction experiments to capture the microstructural evolution of nickel-based single-crystal superalloys during the rapid laser remelting process. In situ synchrotron radiation Laue diffraction characterises the crystal rotation behaviour and stray grain formation process. With a complementary thermomechanical coupled finite element simulation and molecular dynamics simulation, we identify that the crystal rotation is governed by the localised heating/cooling heterogeneity-induced deformation gradient and recognise that the sub-grain rotation caused by rapid dislocation movement could be the origin of granular stray grains at the bottom of the melt pool.