Revealing Nanoscale deformation mechanisms caused by shear-based material removal on individual grains of a Ni-based superalloy
Dongdong Xu, Thomas Edward James Edwards, Zhirong Liao, Xavier Maeder, Rajaprakash Ramachandramoorthy, Manish Jain, Johann Michler, Dragoş Axinte
Abstract
Shear-based material removal processes significantly influence the quality of workpiece surface and implicitly the component functional performance. An in-situ SEM nano-cutting enabled the study of crystal flow and lattice rotation occurring below the cutting edge in a polycrystalline Nickel superalloy. When nano-cutting within single grains a deformed nanolayer appears that consists of a crystal lattice rotated exclusively within the cutting plane which is delimited from the bulk of the grain by high angle boundary (HAB); the depth of deformed nanolayer increases with the material pile-up (nano-chip) caused by the grain shearing. Upon nano-cutting multiple grains, nano-recrystallisation at the HAB occurs, accompanied by the bending of the grain boundary (GB) in the cutting direction, a phenomenon that also significantly influences the deformation behaviour of the grains cut after passing the GB. Clarifying these aspects at the nanoscale is crucial for understanding the formation of workpiece surface damage after material removal operations.