Orientation sensitivity of focused ion beam damage in pure zirconium: direct experimental observations and molecular dynamics simulations

• Published in: Philosophical magazine (Abingdon, England) Vol. 94; no. 14; pp. 1601 - 1621
• Main Authors: Revelly, A.K., Srinivasan, N., Panwar, A.S., Mani Krishna, K.V., Tewari, R., Srivastava, D., Dey, G.K., Samajdar, I.
• Format: Journal Article
• Language: English
• Published: Abingdon Taylor & Francis 13.05.2014
• Subjects: Applied sciences; Computer simulation; Condensed matter: structure, mechanical and thermal properties; Damage; Density; EBSD; Electron back scatter diffraction; Exact sciences and technology; FIB; Fractures; Ion beams; ion damage; irradiation hardening; Mechanical properties and methods of testing. Rheology. Fracture mechanics. Tribology; Metals. Metallurgy; microstructure; microtexture; Molecular dynamics; Orientation; Physics; Structure of solids and liquids; crystallography; Structure of specific crystalline solids; Zirconium; Gallium; Crystal orientation; Cross section; Molecular dynamics method; Nanoindentation; Theoretical study; Cross section (collision); Focused ion beam technology; EBSD; Single crystal; Hardening; Anisotropy; Radiation effect; Kinetics; Atom scattering; Damaging; Crystalline structure
• ISSN: 1478-6435; 1478-6443
• DOI: 10.1080/14786435.2014.892220

A high-purity predominantly single crystalline zirconium was subjected to controlled focused ion beam (FIB) damage. Damage estimates were obtained from electron backscattered diffraction (EBSD) and nano-indentation measurements on exactly the same area/orientation. The damage kinetics, between different crystallographic orientations, differed by one order of magnitude and a clear hierarchy of orientation sensitive ion damage emerged. Use of a simple geometric approach, linear density of atoms and corresponding scattering cross-sections to impinging gallium ions, could differentiate between extreme damage kinetics; but failed when such differences were relatively minor. Numerically intensive molecular dynamics (MD) simulations, on the other hand, were more effective. However, MD simulations or direct EBSD observations failed to justify anisotropic irradiation hardening (AIH): 3-8 times more hardening for near basal. Though explanation for AIH is indirect, evidence and rationalization for orientation-sensitive radiation damage appears clear and statistically reproducible.