Irradiation hardening and microstructure evolution of ion-irradiated Zr-hydride

► A ε-Zr-hydride was irradiated with 6.4 MeV Fe3+ ions. ► Irradiation hardening was measured by nano-indentation tests. ► New fine twin bands and tangled dislocations were formed under the indent prints. ► Cracks were clearly induced in the indent prints after irradiation. ► The irradiation-induced defects make the deformation of ε-Zr-hydride difficult.