Texture evolution and operative mechanisms during large-strain deformation of nanocrystalline nickel

Abstract

The large-strain deformation of nanocrystalline nickel was investigated at room temperature and cryogenic (liquid N₂) temperature. Deformation mechanisms ranging from grain boundary sliding to slip, operate due to a wide distribution of grain sizes. These mechanisms leave their finger print in the deformation texture evolution during rolling of nanocrystalline nickel. The occurrence and severance of different mechanisms is understood by a thorough characterization of the deformed samples using X-ray diffraction, X-ray texture measurements, electron back-scattered diffraction and transmission electron microscopy. Crystal plasticity-based viscoplastic self-consistent simulations were used to further substantiate the experimental observations. Thus, a comprehensive understanding of deformation behavior of nanocrystalline nickel, which is characterized by simultaneous operation of dislocation-dominated and grain boundary-mediated mechanisms, has been developed.

Keywords:

• nanocrystalline material
• nickel
• plastic deformation
• texture
• grain growth

Acknowledgements

The authors are grateful to Prof. R.K. Ray (TATA Steel, India), Prof. L.S. Tóth (University of Metz, France) and Dr. C.N. Tóme (Los Alamos National Laboratory, USA) for discussions on various aspects of texture evolution in FCC materials. They also thank Dr. Apu Sarkar and MJNV Prasad for their help at various stages of this work. The X-ray texture measurements were carried out at National Facility for Texture and Microtexture at IIT, Bombay for which the authors thank Department of Science and Technology (DST), government of India and Prof. I. Samajdar, the coordinator of this facility. The authors acknowledge DST for the microscopy facility at the Institute Nano Science Initiative in Indian Institute of Science, Bangalore.