Systematic study of He induced nano-fiber formation of W and other period 6 transition metals

Systematic study of nano-fiber formation by He plasma irradiation on period 6 metals (Ta, W, Re, Ir, Pt, Au) was performed. Under the same He plasma irradiation conditions (flux, fluence, and ion energy), long nano-fibers were produced on W, Re, and Ir among which the nano-fibers on Re had the highest growth rate. On the other hand, Ta, Pt and Au did not show long nano-fibers (slight nano-fiber formation was seen on Pt). The transition metals in favor of the nano-fiber formation are stiff materials with high Young's and shear moduli. In addition, stiff materials tend to have high He binding energies with He clusters at vacancies. It is speculated that stiffness could contribute to generation of high stress field and high pressure He bubble formation, which are possibly important for nano-fiber formation. (C) 2018 Elsevier B.V. All rights reserved.