Abstract: The microstructure evolution induced by Ar⁺ irradiation (room temperature, about 10 dpa) in nickel based alloy Hastelloy C276 was studied using molecular dynamics and cluster dynamics, and a multiscale modeling code Radieff was constructed based on rate theory. The nucleation and growth of interstitial dislocation loops and void were studied by Radieff code. C276 was irradiated by 115 keV Ar⁺ at room temperature as validation experiment using transmission electron microscope (TEM) implanter/accelerator interface facility at Wuhan University, and the microstructure evolution was observed by TEM. The size of dislocation loops simulated by Radieff is in good agreement with experiment.