The effect of dislocations on MnNi-rich clusters in self-ion irradiated FeMnNi alloy

Abstract

The effect of dislocations on irradiation-induced MnNi-rich clusters in self-ion irradiated FeMnNi alloy was investigated using X-ray diffraction (XRD), nanoindentation, positron annihilation Doppler broadening spectroscopy (PADBS), and atom probe tomography (APT). The nanoindentation results showed that irradiation-induced hardening decreased with dislocation density increasing. The results of APT and PADBS revealed that high-energy Fe-ion irradiation generates high-density MnNi-rich clusters and large vacancy-type defects in irradiated FeMnNi alloy. Note that dense dislocations suppress the formation of large vacancy-type defects and MnNi-rich clusters. By analyzing the effect of dislocations on point defects (PDs), diffusion of Mn and Ni atoms, and nucleation of MnNi-rich clusters, we found that nucleation mechanism of MnNi-rich clusters is strongly dependent on the flux of PDs. However, high-density dislocations can facilitate to annihilate irradiation-induced PDs and cause the decline of defect-solute coupling fluxes, which are responsible for a reduction in number density and mole fraction of MnNi-rich clusters.