| In this paper, 120keV proton, nitrogen-ion, argon-ion irradiation tests were carried out on Zr-702 by using a positive ion irradiation facility. The nano-hardness, tensile properties, in-situ tensile deformation and friction-wear behaviors of Zr-702 before and after irradiation have been evaluated. And the related irradiation hardening mechanism has also been investigated by means of X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS) and transmission electron microscope (TEM).It is shown that the tensile strength of Zr-702 increased and fracture strain slightly decreased after argon ion irradiation, while no change after proton or nitrogen ion irradiation. The surface nano-hardness of Zr-702 increased obviously with the increase of the argon ion fluence, and reached a peak along the incidence direction. The in-situ SEM observations indicated that argon ion and nitrogen irradiations led to subsiding of large grain, surface chapping and crack forming by conglomeration of microcracks during tensile deformation of Zr-702. The main crack propagated in the direction perpendicular to the tensile direction. The average coefficient of friction of Zr-702 increased after argon ion irradiation with lower fluence, and the wear rate increased with the presence of abrasive wear. But both the average coefficient of friction and wear rate Zr-702 decreased as the argon ion irradiation reached 2×1016/cm2.The mechanical properties and microstructure development in Zr-702 after ion irradiation result from the irradiation hardening. The irradiation hardening effects decrease in the turn of argon ion irradiation, nitrogen ion irradiation and proton irradiation. Solute strengthening and defects strengthening are thought to be responsible for the irradiation hardening. With the increase of ion irradiation fluence, the crystal aberration extends, while large size defect forms with the movement of point defects, resulting in the increased hardening effects. |
PDF Full Text Request