Positron annihilation study of vacancy-type defects in high-speed deformed Ni, Cu and Fe

Hideaki Ohkubo, Z. Tang, Y. Nagai, M. Hasegawa, T. Tawara, M. Kiritani

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148 Citations (Scopus)


Vacancies and vacancy clusters in Ni, Cu, and Fe induced by high- and low-speed deformations are studied systematically by positron annihilation techniques and are compared with those induced by the conventional-rolling. To clarify the nature of the defects, the experimental results are compared with our superimposed-atomic-charge calculations of the positron lifetimes in the vacancy clusters as a function of their size. It is found that the deformation-induced defects in the fcc and bcc metals are significantly distinct. In the fcc metals of Ni and Cu, monovacancies with high number densities are induced by the high- and low-speed deformations and by heavy conventional-rolling (> 10% in Ni and > 40% in Cu). Vacancy clusters are observed after the high- and low-speed deformation for Ni and after the conventional-rolling for Cu. On the contrary, dislocations and vacancy clusters are introduced in bcc Fe regardless of the type or degree of deformation.

Original languageEnglish
Pages (from-to)95-101
Number of pages7
JournalMaterials Science & Engineering A: Structural Materials: Properties, Microstructure and Processing
Issue number1-2
Publication statusPublished - 2003 Jun 15


  • Cu
  • Fe
  • High-speed deformation
  • Ni
  • Positron
  • Rolling
  • Superimposed-atomic-charge calculations


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