Comparison between in-situ and post-irradiation cyclic deformation structures in ni by 150MeV proton irradiation

Abstract

Stress-controlled cyclic deformation experiments under 150MeV proton irradiation (5.2 × 10-111 dpa/s) were performed on Ni at room temperature, where a single deformation period was approximately 30 s. After deformation, defect structures were studied using positron annihilation lifetime spectroscopy and transmission electron microscopy. In deformations of 300 cycles and 900 cycles, residual vacancies were high in in-situ cyclic deformed Ni and low in nonirradiated Ni. Although dislocation cell structures were observed in all specimens, the development process and the cell size were different in each deformation condition. Well-developed large cells in nonirradiated Ni and small cells in deformed Ni after irradiation were observed. The cell structure was not well developed in the in-situ deformed Ni under irradiation. The relationship between these defect evolutions and fatigue life is discussed. © 2014 The Japan Institute of Metals and Materials.